Merging upstream version 1.37.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

67 files changed, 10667 insertions, 10262 deletions

diff --git a/database/engine/Makefile.am b/database/engine/Makefile.am
index 43405001d..59250a997 100644
--- a/database/engine/Makefile.am
+++ b/database/engine/Makefile.am
@@ -4,7 +4,6 @@ AUTOMAKE_OPTIONS = subdir-objects
 MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
 
 SUBDIRS = \
-    metadata_log \
     $(NULL)
 
 dist_noinst_DATA = \
diff --git a/database/engine/datafile.c b/database/engine/datafile.c
index 2ed98ef88..9c70068d9 100644
--- a/database/engine/datafile.c
+++ b/database/engine/datafile.c
@@ -174,7 +174,7 @@ int create_data_file(struct rrdengine_datafile *datafile)
         rrd_stat_atomic_add(&global_io_errors, 1);
     }
     uv_fs_req_cleanup(&req);
-    free(superblock);
+    posix_memfree(superblock);
     if (ret < 0) {
         destroy_data_file(datafile);
         return ret;
@@ -218,7 +218,7 @@ static int check_data_file_superblock(uv_file file)
         ret = 0;
     }
     error:
-    free(superblock);
+    posix_memfree(superblock);
     return ret;
 }
 
@@ -444,44 +444,17 @@ void finalize_data_files(struct rrdengine_instance *ctx)
     struct rrdengine_journalfile *journalfile;
     struct extent_info *extent, *next_extent;
 
-    size_t extents_number = 0;
-    size_t extents_bytes = 0;
-    size_t page_compressed_sizes = 0;
-
-    size_t files_number = 0;
-    size_t files_bytes = 0;
-
     for (datafile = ctx->datafiles.first ; datafile != NULL ; datafile = next_datafile) {
         journalfile = datafile->journalfile;
         next_datafile = datafile->next;
 
         for (extent = datafile->extents.first ; extent != NULL ; extent = next_extent) {
-            extents_number++;
-            extents_bytes += sizeof(*extent) + sizeof(struct rrdeng_page_descr *) * extent->number_of_pages;
-            page_compressed_sizes += extent->size;
-
             next_extent = extent->next;
             freez(extent);
         }
         close_journal_file(journalfile, datafile);
         close_data_file(datafile);
-
-        files_number++;
-        files_bytes += sizeof(*journalfile) + sizeof(*datafile);
-
         freez(journalfile);
         freez(datafile);
     }
-
-    if(!files_number) files_number = 1;
-    if(!extents_number) extents_number = 1;
-
-    info("DBENGINE STATISTICS ON DATAFILES:"
-         " Files %zu, structures %zu bytes, %0.2f bytes per file."
-         " Extents %zu, structures %zu bytes, %0.2f bytes per extent."
-         " Compressed size of all pages: %zu bytes."
-         , files_number, files_bytes, (double)files_bytes/files_number
-         , extents_number, extents_bytes, (double)extents_bytes/extents_number
-         , page_compressed_sizes
-         );
 }
diff --git a/database/engine/datafile.h b/database/engine/datafile.h
index ae94bfdd0..1cf256aff 100644
--- a/database/engine/datafile.h
+++ b/database/engine/datafile.h
@@ -52,16 +52,16 @@ struct rrdengine_datafile_list {
     struct rrdengine_datafile *last; /* newest */
 };
 
-extern void df_extent_insert(struct extent_info *extent);
-extern void datafile_list_insert(struct rrdengine_instance *ctx, struct rrdengine_datafile *datafile);
-extern void datafile_list_delete(struct rrdengine_instance *ctx, struct rrdengine_datafile *datafile);
-extern void generate_datafilepath(struct rrdengine_datafile *datafile, char *str, size_t maxlen);
-extern int close_data_file(struct rrdengine_datafile *datafile);
-extern int unlink_data_file(struct rrdengine_datafile *datafile);
-extern int destroy_data_file(struct rrdengine_datafile *datafile);
-extern int create_data_file(struct rrdengine_datafile *datafile);
-extern int create_new_datafile_pair(struct rrdengine_instance *ctx, unsigned tier, unsigned fileno);
-extern int init_data_files(struct rrdengine_instance *ctx);
-extern void finalize_data_files(struct rrdengine_instance *ctx);
+void df_extent_insert(struct extent_info *extent);
+void datafile_list_insert(struct rrdengine_instance *ctx, struct rrdengine_datafile *datafile);
+void datafile_list_delete(struct rrdengine_instance *ctx, struct rrdengine_datafile *datafile);
+void generate_datafilepath(struct rrdengine_datafile *datafile, char *str, size_t maxlen);
+int close_data_file(struct rrdengine_datafile *datafile);
+int unlink_data_file(struct rrdengine_datafile *datafile);
+int destroy_data_file(struct rrdengine_datafile *datafile);
+int create_data_file(struct rrdengine_datafile *datafile);
+int create_new_datafile_pair(struct rrdengine_instance *ctx, unsigned tier, unsigned fileno);
+int init_data_files(struct rrdengine_instance *ctx);
+void finalize_data_files(struct rrdengine_instance *ctx);
 
 #endif /* NETDATA_DATAFILE_H */
\ No newline at end of file
diff --git a/database/engine/journalfile.c b/database/engine/journalfile.c
index dc61f569d..500dd7880 100644
--- a/database/engine/journalfile.c
+++ b/database/engine/journalfile.c
@@ -17,7 +17,7 @@ static void flush_transaction_buffer_cb(uv_fs_t* req)
     }
 
     uv_fs_req_cleanup(req);
-    free(io_descr->buf);
+    posix_memfree(io_descr->buf);
     freez(io_descr);
 }
 
@@ -225,7 +225,7 @@ int create_journal_file(struct rrdengine_journalfile *journalfile, struct rrdeng
         rrd_stat_atomic_add(&global_io_errors, 1);
     }
     uv_fs_req_cleanup(&req);
-    free(superblock);
+    posix_memfree(superblock);
     if (ret < 0) {
         destroy_journal_file(journalfile, datafile);
         return ret;
@@ -268,7 +268,7 @@ static int check_journal_file_superblock(uv_file file)
         ret = 0;
     }
     error:
-    free(superblock);
+    posix_memfree(superblock);
     return ret;
 }
 
@@ -311,20 +311,46 @@ static void restore_extent_metadata(struct rrdengine_instance *ctx, struct rrden
             }
             continue;
         }
-        uint64_t start_time = jf_metric_data->descr[i].start_time;
-        uint64_t end_time = jf_metric_data->descr[i].end_time;
+        uint64_t start_time_ut = jf_metric_data->descr[i].start_time_ut;
+        uint64_t end_time_ut = jf_metric_data->descr[i].end_time_ut;
+        size_t entries = jf_metric_data->descr[i].page_length / page_type_size[page_type];
+        time_t update_every_s = (entries > 1) ? ((end_time_ut - start_time_ut) / USEC_PER_SEC / (entries - 1)) : 0;
+
+        if (unlikely(start_time_ut > end_time_ut)) {
+            ctx->load_errors[LOAD_ERRORS_PAGE_FLIPPED_TIME].counter++;
+            if(ctx->load_errors[LOAD_ERRORS_PAGE_FLIPPED_TIME].latest_end_time_ut < end_time_ut)
+                ctx->load_errors[LOAD_ERRORS_PAGE_FLIPPED_TIME].latest_end_time_ut = end_time_ut;
+            continue;
+        }
 
-        if (unlikely(start_time > end_time)) {
-            error("Invalid page encountered, start time %lu > end time %lu", start_time , end_time );
+        if (unlikely(start_time_ut == end_time_ut && entries != 1)) {
+            ctx->load_errors[LOAD_ERRORS_PAGE_EQUAL_TIME].counter++;
+            if(ctx->load_errors[LOAD_ERRORS_PAGE_EQUAL_TIME].latest_end_time_ut < end_time_ut)
+                ctx->load_errors[LOAD_ERRORS_PAGE_EQUAL_TIME].latest_end_time_ut = end_time_ut;
             continue;
         }
 
-        if (unlikely(start_time == end_time)) {
-            size_t entries = jf_metric_data->descr[i].page_length / page_type_size[page_type];
-            if (unlikely(entries > 1)) {
-                error("Invalid page encountered, start time %lu = end time but %zu entries were found", start_time, entries);
-                continue;
-            }
+        if (unlikely(!entries)) {
+            ctx->load_errors[LOAD_ERRORS_PAGE_ZERO_ENTRIES].counter++;
+            if(ctx->load_errors[LOAD_ERRORS_PAGE_ZERO_ENTRIES].latest_end_time_ut < end_time_ut)
+                ctx->load_errors[LOAD_ERRORS_PAGE_ZERO_ENTRIES].latest_end_time_ut = end_time_ut;
+            continue;
+        }
+
+        if(entries > 1 && update_every_s == 0) {
+            ctx->load_errors[LOAD_ERRORS_PAGE_UPDATE_ZERO].counter++;
+            if(ctx->load_errors[LOAD_ERRORS_PAGE_UPDATE_ZERO].latest_end_time_ut < end_time_ut)
+                ctx->load_errors[LOAD_ERRORS_PAGE_UPDATE_ZERO].latest_end_time_ut = end_time_ut;
+            continue;
+        }
+
+        if(start_time_ut + update_every_s * USEC_PER_SEC * (entries - 1) != end_time_ut) {
+            ctx->load_errors[LOAD_ERRORS_PAGE_FLEXY_TIME].counter++;
+            if(ctx->load_errors[LOAD_ERRORS_PAGE_FLEXY_TIME].latest_end_time_ut < end_time_ut)
+                ctx->load_errors[LOAD_ERRORS_PAGE_FLEXY_TIME].latest_end_time_ut = end_time_ut;
+
+            // let this be
+            // end_time_ut = start_time_ut + update_every_s * USEC_PER_SEC * (entries - 1);
         }
 
         temp_id = (uuid_t *)jf_metric_data->descr[i].uuid;
@@ -340,7 +366,7 @@ static void restore_extent_metadata(struct rrdengine_instance *ctx, struct rrden
             uv_rwlock_wrlock(&pg_cache->metrics_index.lock);
             PValue = JudyHSIns(&pg_cache->metrics_index.JudyHS_array, temp_id, sizeof(uuid_t), PJE0);
             fatal_assert(NULL == *PValue); /* TODO: figure out concurrency model */
-            *PValue = page_index = create_page_index(temp_id);
+            *PValue = page_index = create_page_index(temp_id, ctx);
             page_index->prev = pg_cache->metrics_index.last_page_index;
             pg_cache->metrics_index.last_page_index = page_index;
             uv_rwlock_wrunlock(&pg_cache->metrics_index.lock);
@@ -348,21 +374,32 @@ static void restore_extent_metadata(struct rrdengine_instance *ctx, struct rrden
 
         descr = pg_cache_create_descr();
         descr->page_length = jf_metric_data->descr[i].page_length;
-        descr->start_time = start_time;
-        descr->end_time = end_time;
+        descr->start_time_ut = start_time_ut;
+        descr->end_time_ut = end_time_ut;
+        descr->update_every_s = (update_every_s > 0) ? (uint32_t)update_every_s : (page_index->latest_update_every_s);
         descr->id = &page_index->id;
         descr->extent = extent;
         descr->type = page_type;
         extent->pages[valid_pages++] = descr;
         pg_cache_insert(ctx, page_index, descr);
+
+        if(page_index->latest_time_ut == descr->end_time_ut)
+            page_index->latest_update_every_s = descr->update_every_s;
+
+        if(descr->update_every_s == 0)
+            fatal(
+                "DBENGINE: page descriptor update every is zero, end_time_ut = %llu, start_time_ut = %llu, entries = %zu",
+                (unsigned long long)end_time_ut, (unsigned long long)start_time_ut, entries);
     }
 
     extent->number_of_pages = valid_pages;
 
     if (likely(valid_pages))
         df_extent_insert(extent);
-    else
+    else {
         freez(extent);
+        ctx->load_errors[LOAD_ERRORS_DROPPED_EXTENT].counter++;
+    }
 }
 
 /*
@@ -442,27 +479,30 @@ static uint64_t iterate_transactions(struct rrdengine_instance *ctx, struct rrde
     //data_file_size = journalfile->datafile->pos; TODO: utilize this?
 
     max_id = 1;
-    ret = posix_memalign((void *)&buf, RRDFILE_ALIGNMENT, READAHEAD_BYTES);
-    if (unlikely(ret)) {
-        fatal("posix_memalign:%s", strerror(ret));
+    bool journal_is_mmapped = (journalfile->data != NULL);
+    if (unlikely(!journal_is_mmapped)) {
+        ret = posix_memalign((void *)&buf, RRDFILE_ALIGNMENT, READAHEAD_BYTES);
+        if (unlikely(ret))
+            fatal("posix_memalign:%s", strerror(ret));
     }
-
+    else
+        buf = journalfile->data +  sizeof(struct rrdeng_jf_sb);
     for (pos = sizeof(struct rrdeng_jf_sb) ; pos < file_size ; pos += READAHEAD_BYTES) {
         size_bytes = MIN(READAHEAD_BYTES, file_size - pos);
-        iov = uv_buf_init(buf, size_bytes);
-        ret = uv_fs_read(NULL, &req, file, &iov, 1, pos, NULL);
-        if (ret < 0) {
-            error("uv_fs_read: pos=%"PRIu64", %s", pos, uv_strerror(ret));
+        if (unlikely(!journal_is_mmapped)) {
+            iov = uv_buf_init(buf, size_bytes);
+            ret = uv_fs_read(NULL, &req, file, &iov, 1, pos, NULL);
+            if (ret < 0) {
+                error("uv_fs_read: pos=%" PRIu64 ", %s", pos, uv_strerror(ret));
+                uv_fs_req_cleanup(&req);
+                goto skip_file;
+            }
+            fatal_assert(req.result >= 0);
             uv_fs_req_cleanup(&req);
-            goto skip_file;
+            ++ctx->stats.io_read_requests;
+            ctx->stats.io_read_bytes += size_bytes;
         }
-        fatal_assert(req.result >= 0);
-        uv_fs_req_cleanup(&req);
-        ctx->stats.io_read_bytes += size_bytes;
-        ++ctx->stats.io_read_requests;
 
-        //pos_i = pos;
-        //while (pos_i < pos + size_bytes) {
         for (pos_i = 0 ; pos_i < size_bytes ; ) {
             unsigned max_size;
 
@@ -475,9 +515,12 @@ static uint64_t iterate_transactions(struct rrdengine_instance *ctx, struct rrde
                 pos_i += ret;
             max_id = MAX(max_id, id);
         }
+        if (likely(journal_is_mmapped))
+            buf += size_bytes;
     }
 skip_file:
-    free(buf);
+    if (unlikely(!journal_is_mmapped))
+        posix_memfree(buf);
     return max_id;
 }
 
@@ -512,12 +555,16 @@ int load_journal_file(struct rrdengine_instance *ctx, struct rrdengine_journalfi
 
     journalfile->file = file;
     journalfile->pos = file_size;
+    journalfile->data = netdata_mmap(path, file_size, MAP_SHARED, 0);
+    info("Loading journal file \"%s\" using %s.", path, journalfile->data?"MMAP":"uv_fs_read");
 
     max_id = iterate_transactions(ctx, journalfile);
 
     ctx->commit_log.transaction_id = MAX(ctx->commit_log.transaction_id, max_id + 1);
 
     info("Journal file \"%s\" loaded (size:%"PRIu64").", path, file_size);
+    if (likely(journalfile->data))
+        netdata_munmap(journalfile->data, file_size);
     return 0;
 
     error:
diff --git a/database/engine/journalfile.h b/database/engine/journalfile.h
index f6c43cd16..011c5065f 100644
--- a/database/engine/journalfile.h
+++ b/database/engine/journalfile.h
@@ -19,7 +19,7 @@ struct rrdengine_journalfile;
 struct rrdengine_journalfile {
     uv_file file;
     uint64_t pos;
-
+    void *data;
     struct rrdengine_datafile *datafile;
 };
 
@@ -33,17 +33,17 @@ struct transaction_commit_log {
     unsigned buf_size;
 };
 
-extern void generate_journalfilepath(struct rrdengine_datafile *datafile, char *str, size_t maxlen);
-extern void journalfile_init(struct rrdengine_journalfile *journalfile, struct rrdengine_datafile *datafile);
-extern void *wal_get_transaction_buffer(struct rrdengine_worker_config* wc, unsigned size);
-extern void wal_flush_transaction_buffer(struct rrdengine_worker_config* wc);
-extern int close_journal_file(struct rrdengine_journalfile *journalfile, struct rrdengine_datafile *datafile);
-extern int unlink_journal_file(struct rrdengine_journalfile *journalfile);
-extern int destroy_journal_file(struct rrdengine_journalfile *journalfile, struct rrdengine_datafile *datafile);
-extern int create_journal_file(struct rrdengine_journalfile *journalfile, struct rrdengine_datafile *datafile);
-extern int load_journal_file(struct rrdengine_instance *ctx, struct rrdengine_journalfile *journalfile,
+void generate_journalfilepath(struct rrdengine_datafile *datafile, char *str, size_t maxlen);
+void journalfile_init(struct rrdengine_journalfile *journalfile, struct rrdengine_datafile *datafile);
+void *wal_get_transaction_buffer(struct rrdengine_worker_config* wc, unsigned size);
+void wal_flush_transaction_buffer(struct rrdengine_worker_config* wc);
+int close_journal_file(struct rrdengine_journalfile *journalfile, struct rrdengine_datafile *datafile);
+int unlink_journal_file(struct rrdengine_journalfile *journalfile);
+int destroy_journal_file(struct rrdengine_journalfile *journalfile, struct rrdengine_datafile *datafile);
+int create_journal_file(struct rrdengine_journalfile *journalfile, struct rrdengine_datafile *datafile);
+int load_journal_file(struct rrdengine_instance *ctx, struct rrdengine_journalfile *journalfile,
                              struct rrdengine_datafile *datafile);
-extern void init_commit_log(struct rrdengine_instance *ctx);
+void init_commit_log(struct rrdengine_instance *ctx);
 
 
 #endif /* NETDATA_JOURNALFILE_H */
\ No newline at end of file
diff --git a/database/engine/metadata_log/Makefile.am b/database/engine/metadata_log/Makefile.am
deleted file mode 100644
index 161784b8f..000000000
--- a/database/engine/metadata_log/Makefile.am
+++ /dev/null
@@ -1,8 +0,0 @@
-# SPDX-License-Identifier: GPL-3.0-or-later
-
-AUTOMAKE_OPTIONS = subdir-objects
-MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
-
-dist_noinst_DATA = \
-    README.md \
-    $(NULL)
diff --git a/database/engine/metadata_log/compaction.c b/database/engine/metadata_log/compaction.c
deleted file mode 100644
index ba19e1edf..000000000
--- a/database/engine/metadata_log/compaction.c
+++ /dev/null
@@ -1,86 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-#define NETDATA_RRD_INTERNALS
-
-#include "metadatalog.h"
-
-/* Return 0 on success. */
-int compaction_failure_recovery(struct metalog_instance *ctx, struct metadata_logfile **metalogfiles,
-                                 unsigned *matched_files)
-{
-    int ret;
-    unsigned starting_fileno, fileno, i, j, recovered_files;
-    struct metadata_logfile *metalogfile = NULL, *compactionfile = NULL, **tmp_metalogfiles;
-    char *dbfiles_path = ctx->rrdeng_ctx->dbfiles_path;
-
-    for (i = 0 ; i < *matched_files ; ++i) {
-        metalogfile = metalogfiles[i];
-        if (0 == metalogfile->starting_fileno)
-            continue; /* skip standard metadata log files */
-        break; /* this is a compaction temporary file */
-    }
-    if (i == *matched_files) /* no recovery needed */
-        return 0;
-    info("Starting metadata log file failure recovery procedure in \"%s\".", dbfiles_path);
-
-    if (*matched_files - i > 1) { /* Can't have more than 1 temporary compaction files */
-        error("Metadata log files are in an invalid state. Cannot proceed.");
-        return 1;
-    }
-    compactionfile = metalogfile;
-    starting_fileno = compactionfile->starting_fileno;
-    fileno = compactionfile->fileno;
-    /* scratchpad space to move file pointers around */
-    tmp_metalogfiles = callocz(*matched_files, sizeof(*tmp_metalogfiles));
-
-    for (j = 0, recovered_files = 0 ; j < i ; ++j) {
-        metalogfile = metalogfiles[j];
-        fatal_assert(0 == metalogfile->starting_fileno);
-        if (metalogfile->fileno < starting_fileno) {
-            tmp_metalogfiles[recovered_files++] = metalogfile;
-            continue;
-        }
-        break; /* reached compaction file serial number */
-    }
-
-    if ((j == i) /* Shouldn't be possible, invalid compaction temporary file */ ||
-        (metalogfile->fileno == starting_fileno && metalogfile->fileno == fileno)) {
-        error("Deleting invalid compaction temporary file \"%s/"METALOG_PREFIX METALOG_FILE_NUMBER_PRINT_TMPL
-              METALOG_EXTENSION"\"", dbfiles_path, starting_fileno, fileno);
-        unlink_metadata_logfile(compactionfile);
-        freez(compactionfile);
-        freez(tmp_metalogfiles);
-        --*matched_files; /* delete the last one */
-
-        info("Finished metadata log file failure recovery procedure in \"%s\".", dbfiles_path);
-        return 0;
-    }
-
-    for ( ; j < i ; ++j) { /* continue iterating through normal metadata log files */
-        metalogfile = metalogfiles[j];
-        fatal_assert(0 == metalogfile->starting_fileno);
-        if (metalogfile->fileno < fileno) { /* It has already been compacted */
-            error("Deleting invalid metadata log file \"%s/"METALOG_PREFIX METALOG_FILE_NUMBER_PRINT_TMPL
-                      METALOG_EXTENSION"\"", dbfiles_path, 0U, metalogfile->fileno);
-            unlink_metadata_logfile(metalogfile);
-            freez(metalogfile);
-            continue;
-        }
-        tmp_metalogfiles[recovered_files++] = metalogfile;
-    }
-
-    /* compaction temporary file is valid */
-    tmp_metalogfiles[recovered_files++] = compactionfile;
-    ret = rename_metadata_logfile(compactionfile, 0, starting_fileno);
-    if (ret < 0) {
-        error("Cannot rename temporary compaction files. Cannot proceed.");
-        freez(tmp_metalogfiles);
-        return 1;
-    }
-
-    memcpy(metalogfiles, tmp_metalogfiles, recovered_files * sizeof(*metalogfiles));
-    *matched_files = recovered_files;
-    freez(tmp_metalogfiles);
-
-    info("Finished metadata log file failure recovery procedure in \"%s\".", dbfiles_path);
-    return 0;
-}
diff --git a/database/engine/metadata_log/compaction.h b/database/engine/metadata_log/compaction.h
deleted file mode 100644
index d04613440..000000000
--- a/database/engine/metadata_log/compaction.h
+++ /dev/null
@@ -1,14 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#ifndef NETDATA_COMPACTION_H
-#define NETDATA_COMPACTION_H
-
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
-#include "../rrdengine.h"
-
-extern int compaction_failure_recovery(struct metalog_instance *ctx, struct metadata_logfile **metalogfiles,
-                                       unsigned *matched_files);
-
-#endif /* NETDATA_COMPACTION_H */
diff --git a/database/engine/metadata_log/logfile.c b/database/engine/metadata_log/logfile.c
deleted file mode 100644
index 07eb9b6fe..000000000
--- a/database/engine/metadata_log/logfile.c
+++ /dev/null
@@ -1,447 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-#include <database/sqlite/sqlite_functions.h>
-#include "metadatalog.h"
-#include "metalogpluginsd.h"
-
-
-void generate_metadata_logfile_path(struct metadata_logfile *metalogfile, char *str, size_t maxlen)
-{
-    (void) snprintfz(str, maxlen, "%s/" METALOG_PREFIX METALOG_FILE_NUMBER_PRINT_TMPL METALOG_EXTENSION,
-                    metalogfile->ctx->rrdeng_ctx->dbfiles_path, metalogfile->starting_fileno, metalogfile->fileno);
-}
-
-void metadata_logfile_init(struct metadata_logfile *metalogfile, struct metalog_instance *ctx, unsigned starting_fileno,
-                           unsigned fileno)
-{
-    metalogfile->starting_fileno = starting_fileno;
-    metalogfile->fileno = fileno;
-    metalogfile->file = (uv_file)0;
-    metalogfile->pos = 0;
-    metalogfile->next = NULL;
-    metalogfile->ctx = ctx;
-}
-
-int rename_metadata_logfile(struct metadata_logfile *metalogfile, unsigned new_starting_fileno, unsigned new_fileno)
-{
-    //struct metalog_instance *ctx = metalogfile->ctx;
-    uv_fs_t req;
-    int ret;
-    char oldpath[RRDENG_PATH_MAX], newpath[RRDENG_PATH_MAX];
-    unsigned backup_starting_fileno, backup_fileno;
-
-    backup_starting_fileno = metalogfile->starting_fileno;
-    backup_fileno = metalogfile->fileno;
-    generate_metadata_logfile_path(metalogfile, oldpath, sizeof(oldpath));
-    metalogfile->starting_fileno = new_starting_fileno;
-    metalogfile->fileno = new_fileno;
-    generate_metadata_logfile_path(metalogfile, newpath, sizeof(newpath));
-
-    info("Renaming metadata log file \"%s\" to \"%s\".", oldpath, newpath);
-    ret = uv_fs_rename(NULL, &req, oldpath, newpath, NULL);
-    if (ret < 0) {
-        error("uv_fs_rename(%s): %s", oldpath, uv_strerror(ret));
-        //++ctx->stats.fs_errors; /* this is racy, may miss some errors */
-        rrd_stat_atomic_add(&global_fs_errors, 1);
-        /* restore previous values */
-        metalogfile->starting_fileno = backup_starting_fileno;
-        metalogfile->fileno = backup_fileno;
-    }
-    uv_fs_req_cleanup(&req);
-
-    return ret;
-}
-
-int unlink_metadata_logfile(struct metadata_logfile *metalogfile)
-{
-    //struct metalog_instance *ctx = metalogfile->ctx;
-    uv_fs_t req;
-    int ret;
-    char path[RRDENG_PATH_MAX];
-
-    generate_metadata_logfile_path(metalogfile, path, sizeof(path));
-
-    ret = uv_fs_unlink(NULL, &req, path, NULL);
-    if (ret < 0) {
-        error("uv_fs_fsunlink(%s): %s", path, uv_strerror(ret));
-//        ++ctx->stats.fs_errors;
-        rrd_stat_atomic_add(&global_fs_errors, 1);
-    }
-    uv_fs_req_cleanup(&req);
-
-    return ret;
-}
-
-static int check_metadata_logfile_superblock(uv_file file)
-{
-    int ret;
-    struct rrdeng_metalog_sb *superblock;
-    uv_buf_t iov;
-    uv_fs_t req;
-
-    ret = posix_memalign((void *)&superblock, RRDFILE_ALIGNMENT, sizeof(*superblock));
-    if (unlikely(ret)) {
-        fatal("posix_memalign:%s", strerror(ret));
-    }
-    iov = uv_buf_init((void *)superblock, sizeof(*superblock));
-
-    ret = uv_fs_read(NULL, &req, file, &iov, 1, 0, NULL);
-    if (ret < 0) {
-        error("uv_fs_read: %s", uv_strerror(ret));
-        uv_fs_req_cleanup(&req);
-        goto error;
-    }
-    fatal_assert(req.result >= 0);
-    uv_fs_req_cleanup(&req);
-
-    if (strncmp(superblock->magic_number, RRDENG_METALOG_MAGIC, RRDENG_MAGIC_SZ)) {
-        error("File has invalid superblock.");
-        ret = UV_EINVAL;
-    } else {
-        ret = 0;
-    }
-    if (superblock->version > RRDENG_METALOG_VER) {
-        error("File has unknown version %"PRIu16". Compatibility is not guaranteed.", superblock->version);
-    }
-error:
-    free(superblock);
-    return ret;
-}
-
-void replay_record(struct metadata_logfile *metalogfile, struct rrdeng_metalog_record_header *header, void *payload)
-{
-    struct metalog_instance *ctx = metalogfile->ctx;
-    char *line, *nextline, *record_end;
-    int ret;
-
-    debug(D_METADATALOG, "RECORD contents: %.*s", (int)header->payload_length, (char *)payload);
-    record_end = (char *)payload + header->payload_length - 1;
-    *record_end = '\0';
-
-    for (line = payload ; line ; line = nextline) {
-        nextline = strchr(line, '\n');
-        if (nextline) {
-            *nextline++ = '\0';
-        }
-        ret = parser_action(ctx->metalog_parser_object->parser, line);
-        debug(D_METADATALOG, "parser_action ret:%d", ret);
-        if (ret)
-            return; /* skip record due to error */
-    };
-}
-
-/* This function only works with buffered I/O */
-static inline int metalogfile_read(struct metadata_logfile *metalogfile, void *buf, size_t len, uint64_t offset)
-{
-//    struct metalog_instance *ctx;
-    uv_file file;
-    uv_buf_t iov;
-    uv_fs_t req;
-    int ret;
-
-//    ctx = metalogfile->ctx;
-    file = metalogfile->file;
-    iov = uv_buf_init(buf, len);
-    ret = uv_fs_read(NULL, &req, file, &iov, 1, offset, NULL);
-    if (unlikely(ret < 0 && ret != req.result)) {
-        fatal("uv_fs_read: %s", uv_strerror(ret));
-    }
-    if (req.result < 0) {
-//        ++ctx->stats.io_errors;
-        rrd_stat_atomic_add(&global_io_errors, 1);
-        error("%s: uv_fs_read - %s - record at offset %"PRIu64"(%u) in metadata logfile %u-%u.", __func__,
-              uv_strerror((int)req.result), offset, (unsigned)len, metalogfile->starting_fileno, metalogfile->fileno);
-    }
-    uv_fs_req_cleanup(&req);
-//    ctx->stats.io_read_bytes += len;
-//    ++ctx->stats.io_read_requests;
-
-    return ret;
-}
-
-/* Return 0 on success */
-static int metadata_record_integrity_check(void *record)
-{
-    int ret;
-    uint32_t data_size;
-    struct rrdeng_metalog_record_header *header;
-    struct rrdeng_metalog_record_trailer *trailer;
-    uLong crc;
-
-    header = record;
-    data_size = header->header_length + header->payload_length;
-    trailer = record + data_size;
-
-    crc = crc32(0L, Z_NULL, 0);
-    crc = crc32(crc, record, data_size);
-    ret = crc32cmp(trailer->checksum, crc);
-
-    return ret;
-}
-
-#define MAX_READ_BYTES (RRDENG_BLOCK_SIZE * 32) /* no record should be over 128KiB in this version */
-
-/*
- * Iterates metadata log file records and creates database objects (host/chart/dimension)
- */
-static void iterate_records(struct metadata_logfile *metalogfile)
-{
-    uint32_t file_size, pos, bytes_remaining, record_size;
-    void *buf;
-    struct rrdeng_metalog_record_header *header;
-    struct metalog_instance *ctx = metalogfile->ctx;
-    struct metalog_pluginsd_state *state = ctx->metalog_parser_object->private;
-    const size_t min_header_size = offsetof(struct rrdeng_metalog_record_header, header_length) +
-                                   sizeof(header->header_length);
-
-    file_size = metalogfile->pos;
-    state->metalogfile = metalogfile;
-
-    buf = mallocz(MAX_READ_BYTES);
-
-    for (pos = sizeof(struct rrdeng_metalog_sb) ; pos < file_size ; pos += record_size) {
-        bytes_remaining = file_size - pos;
-        if (bytes_remaining < min_header_size) {
-            error("%s: unexpected end of file in metadata logfile %u-%u.", __func__, metalogfile->starting_fileno,
-                  metalogfile->fileno);
-            break;
-        }
-        if (metalogfile_read(metalogfile, buf, min_header_size, pos) < 0)
-            break;
-        header = (struct rrdeng_metalog_record_header *)buf;
-        if (METALOG_STORE_PADDING == header->type) {
-            info("%s: Skipping padding in metadata logfile %u-%u.", __func__, metalogfile->starting_fileno,
-                 metalogfile->fileno);
-            record_size = ALIGN_BYTES_FLOOR(pos + RRDENG_BLOCK_SIZE) - pos;
-            continue;
-        }
-        if (metalogfile_read(metalogfile, buf + min_header_size, sizeof(*header) - min_header_size,
-                             pos + min_header_size) < 0)
-            break;
-        record_size = header->header_length + header->payload_length + sizeof(struct rrdeng_metalog_record_trailer);
-        if (header->header_length < min_header_size || record_size > bytes_remaining) {
-            error("%s: Corrupted record in metadata logfile %u-%u.", __func__, metalogfile->starting_fileno,
-                  metalogfile->fileno);
-            break;
-        }
-        if (record_size > MAX_READ_BYTES) {
-            error("%s: Record is too long (%u bytes) in metadata logfile %u-%u.", __func__, record_size,
-                  metalogfile->starting_fileno, metalogfile->fileno);
-            continue;
-        }
-        if (metalogfile_read(metalogfile, buf + sizeof(*header), record_size - sizeof(*header),
-                             pos + sizeof(*header)) < 0)
-            break;
-        if (metadata_record_integrity_check(buf)) {
-            error("%s: Record at offset %"PRIu32" was read from disk. CRC32 check: FAILED", __func__, pos);
-            continue;
-        }
-        debug(D_METADATALOG, "%s: Record at offset %"PRIu32" was read from disk. CRC32 check: SUCCEEDED", __func__,
-              pos);
-
-        replay_record(metalogfile, header, buf + header->header_length);
-    }
-
-    freez(buf);
-}
-
-int load_metadata_logfile(struct metalog_instance *ctx, struct metadata_logfile *metalogfile)
-{
-    UNUSED(ctx);
-    uv_fs_t req;
-    uv_file file;
-    int ret, fd, error;
-    uint64_t file_size;
-    char path[RRDENG_PATH_MAX];
-
-    generate_metadata_logfile_path(metalogfile, path, sizeof(path));
-    if (file_is_migrated(path))
-        return 0;
-
-    fd = open_file_buffered_io(path, O_RDWR, &file);
-    if (fd < 0) {
-//        ++ctx->stats.fs_errors;
-        rrd_stat_atomic_add(&global_fs_errors, 1);
-        return fd;
-    }
-    info("Loading metadata log \"%s\".", path);
-
-    ret = check_file_properties(file, &file_size, sizeof(struct rrdeng_metalog_sb));
-    if (ret)
-        goto error;
-
-    ret = check_metadata_logfile_superblock(file);
-    if (ret)
-        goto error;
-//    ctx->stats.io_read_bytes += sizeof(struct rrdeng_jf_sb);
-//    ++ctx->stats.io_read_requests;
-
-    metalogfile->file = file;
-    metalogfile->pos = file_size;
-
-    iterate_records(metalogfile);
-
-    info("Metadata log \"%s\" migrated to the database (size:%"PRIu64").", path, file_size);
-    add_migrated_file(path, file_size);
-    return 0;
-
-error:
-    error = ret;
-    ret = uv_fs_close(NULL, &req, file, NULL);
-    if (ret < 0) {
-        error("uv_fs_close(%s): %s", path, uv_strerror(ret));
-//        ++ctx->stats.fs_errors;
-        rrd_stat_atomic_add(&global_fs_errors, 1);
-    }
-    uv_fs_req_cleanup(&req);
-    return error;
-}
-
-static int scan_metalog_files_cmp(const void *a, const void *b)
-{
-    struct metadata_logfile *file1, *file2;
-    char path1[RRDENG_PATH_MAX], path2[RRDENG_PATH_MAX];
-
-    file1 = *(struct metadata_logfile **)a;
-    file2 = *(struct metadata_logfile **)b;
-    generate_metadata_logfile_path(file1, path1, sizeof(path1));
-    generate_metadata_logfile_path(file2, path2, sizeof(path2));
-    return strcmp(path1, path2);
-}
-
-/* Returns number of metadata logfiles that were loaded or < 0 on error */
-static int scan_metalog_files(struct metalog_instance *ctx)
-{
-    int ret;
-    unsigned starting_no, no, matched_files, i, failed_to_load;
-    static uv_fs_t req;
-    uv_dirent_t dent;
-    struct metadata_logfile **metalogfiles, *metalogfile;
-    char *dbfiles_path = ctx->rrdeng_ctx->dbfiles_path;
-
-    ret = uv_fs_scandir(NULL, &req, dbfiles_path, 0, NULL);
-    if (ret < 0) {
-        fatal_assert(req.result < 0);
-        uv_fs_req_cleanup(&req);
-        error("uv_fs_scandir(%s): %s", dbfiles_path, uv_strerror(ret));
-//        ++ctx->stats.fs_errors;
-        rrd_stat_atomic_add(&global_fs_errors, 1);
-        return ret;
-    }
-    info("Found %d files in path %s", ret, dbfiles_path);
-
-    metalogfiles = callocz(MIN(ret, MAX_DATAFILES), sizeof(*metalogfiles));
-    for (matched_files = 0 ; UV_EOF != uv_fs_scandir_next(&req, &dent) && matched_files < MAX_DATAFILES ; ) {
-        info("Scanning file \"%s/%s\"", dbfiles_path, dent.name);
-        ret = sscanf(dent.name, METALOG_PREFIX METALOG_FILE_NUMBER_SCAN_TMPL METALOG_EXTENSION, &starting_no, &no);
-        if (2 == ret) {
-            info("Matched file \"%s/%s\"", dbfiles_path, dent.name);
-            metalogfile = mallocz(sizeof(*metalogfile));
-            metadata_logfile_init(metalogfile, ctx, starting_no, no);
-            metalogfiles[matched_files++] = metalogfile;
-        }
-    }
-    uv_fs_req_cleanup(&req);
-
-    if (0 == matched_files) {
-        freez(metalogfiles);
-        return 0;
-    }
-    if (matched_files == MAX_DATAFILES) {
-        error("Warning: hit maximum database engine file limit of %d files", MAX_DATAFILES);
-    }
-    qsort(metalogfiles, matched_files, sizeof(*metalogfiles), scan_metalog_files_cmp);
-    ret = compaction_failure_recovery(ctx, metalogfiles, &matched_files);
-    if (ret) { /* If the files are corrupted fail */
-        for (i = 0 ; i < matched_files ; ++i) {
-            freez(metalogfiles[i]);
-        }
-        freez(metalogfiles);
-        return UV_EINVAL;
-    }
-    //ctx->last_fileno = metalogfiles[matched_files - 1]->fileno;
-
-    struct plugind cd = {
-        .enabled = 1,
-        .update_every = 0,
-        .pid = 0,
-        .serial_failures = 0,
-        .successful_collections = 0,
-        .obsolete = 0,
-        .started_t = INVALID_TIME,
-        .next = NULL,
-        .version = 0,
-    };
-
-    struct metalog_pluginsd_state metalog_parser_state;
-    metalog_pluginsd_state_init(&metalog_parser_state, ctx);
-
-    PARSER_USER_OBJECT metalog_parser_object = {
-        .enabled = cd.enabled,
-        .host = ctx->rrdeng_ctx->host,
-        .cd = &cd,
-        .trust_durations = 0,
-        .private = &metalog_parser_state
-    };
-
-    PARSER *parser = parser_init(metalog_parser_object.host, &metalog_parser_object, NULL, PARSER_INPUT_SPLIT);
-    parser_add_keyword(parser, PLUGINSD_KEYWORD_HOST, metalog_pluginsd_host);
-    parser_add_keyword(parser, PLUGINSD_KEYWORD_GUID, pluginsd_guid);
-    parser_add_keyword(parser, PLUGINSD_KEYWORD_CONTEXT, pluginsd_context);
-    parser_add_keyword(parser, PLUGINSD_KEYWORD_TOMBSTONE, pluginsd_tombstone);
-    parser->plugins_action->dimension_action = &metalog_pluginsd_dimension_action;
-    parser->plugins_action->chart_action     = &metalog_pluginsd_chart_action;
-    parser->plugins_action->guid_action      = &metalog_pluginsd_guid_action;
-    parser->plugins_action->context_action   = &metalog_pluginsd_context_action;
-    parser->plugins_action->tombstone_action = &metalog_pluginsd_tombstone_action;
-    parser->plugins_action->host_action      = &metalog_pluginsd_host_action;
-
-
-    metalog_parser_object.parser = parser;
-    ctx->metalog_parser_object = &metalog_parser_object;
-
-    for (failed_to_load = 0, i = 0 ; i < matched_files ; ++i) {
-        metalogfile = metalogfiles[i];
-        db_lock();
-        db_execute("BEGIN TRANSACTION;");
-        ret = load_metadata_logfile(ctx, metalogfile);
-        if (0 != ret) {
-            error("Deleting invalid metadata log file \"%s/"METALOG_PREFIX METALOG_FILE_NUMBER_PRINT_TMPL
-                      METALOG_EXTENSION"\"", dbfiles_path, metalogfile->starting_fileno, metalogfile->fileno);
-            unlink_metadata_logfile(metalogfile);
-            ++failed_to_load;
-            db_execute("ROLLBACK TRANSACTION;");
-        }
-        else
-            db_execute("COMMIT TRANSACTION;");
-        db_unlock();
-        freez(metalogfile);
-    }
-    matched_files -= failed_to_load;
-    debug(D_METADATALOG, "PARSER ended");
-
-    parser_destroy(parser);
-
-    size_t count __maybe_unused = metalog_parser_object.count;
-
-    debug(D_METADATALOG, "Parsing count=%u", (unsigned)count);
-
-    freez(metalogfiles);
-    return matched_files;
-}
-
-/* Return 0 on success. */
-int init_metalog_files(struct metalog_instance *ctx)
-{
-    int ret;
-    char *dbfiles_path = ctx->rrdeng_ctx->dbfiles_path;
-
-    ret = scan_metalog_files(ctx);
-    if (ret < 0) {
-        error("Failed to scan path \"%s\".", dbfiles_path);
-        return ret;
-    }/* else if (0 == ret) {
-        ctx->last_fileno = 1;
-    }*/
-
-    return 0;
-}
diff --git a/database/engine/metadata_log/logfile.h b/database/engine/metadata_log/logfile.h
deleted file mode 100644
index df12ac714..000000000
--- a/database/engine/metadata_log/logfile.h
+++ /dev/null
@@ -1,39 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#ifndef NETDATA_LOGFILE_H
-#define NETDATA_LOGFILE_H
-
-#include "metadatalogprotocol.h"
-#include "../rrdengine.h"
-
-/* Forward declarations */
-struct metadata_logfile;
-struct metalog_worker_config;
-
-#define METALOG_PREFIX "metadatalog-"
-#define METALOG_EXTENSION ".mlf"
-
-/* only one event loop is supported for now */
-struct metadata_logfile {
-    unsigned fileno; /* Starts at 1 */
-    unsigned starting_fileno; /* 0 for normal files, staring number during compaction */
-    uv_file file;
-    uint64_t pos;
-    struct metalog_instance *ctx;
-    struct metadata_logfile *next;
-};
-
-struct metadata_logfile_list {
-    struct metadata_logfile *first; /* oldest */
-    struct metadata_logfile *last; /* newest */
-};
-
-extern void generate_metadata_logfile_path(struct metadata_logfile *metadatalog, char *str, size_t maxlen);
-extern int rename_metadata_logfile(struct metadata_logfile *metalogfile, unsigned new_starting_fileno,
-                                   unsigned new_fileno);
-extern int unlink_metadata_logfile(struct metadata_logfile *metalogfile);
-extern int load_metadata_logfile(struct metalog_instance *ctx, struct metadata_logfile *logfile);
-extern int init_metalog_files(struct metalog_instance *ctx);
-
-
-#endif /* NETDATA_LOGFILE_H */
diff --git a/database/engine/metadata_log/metadatalog.h b/database/engine/metadata_log/metadatalog.h
deleted file mode 100644
index 483036a91..000000000
--- a/database/engine/metadata_log/metadatalog.h
+++ /dev/null
@@ -1,28 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#ifndef NETDATA_METADATALOG_H
-#define NETDATA_METADATALOG_H
-
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
-#include "../rrdengine.h"
-#include "metadatalogprotocol.h"
-#include "logfile.h"
-#include "metadatalogapi.h"
-#include "compaction.h"
-
-/* Forward declarations */
-struct metalog_instance;
-struct parser_user_object;
-
-#define METALOG_FILE_NUMBER_SCAN_TMPL "%5u-%5u"
-#define METALOG_FILE_NUMBER_PRINT_TMPL "%5.5u-%5.5u"
-
-struct metalog_instance {
-    struct rrdengine_instance *rrdeng_ctx;
-    struct parser_user_object *metalog_parser_object;
-    uint8_t initialized; /* set to 1 to mark context initialized */
-};
-
-#endif /* NETDATA_METADATALOG_H */
diff --git a/database/engine/metadata_log/metadatalogapi.c b/database/engine/metadata_log/metadatalogapi.c
deleted file mode 100755
index b206cca05..000000000
--- a/database/engine/metadata_log/metadatalogapi.c
+++ /dev/null
@@ -1,39 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-#define NETDATA_RRD_INTERNALS
-
-#include "metadatalog.h"
-
-/*
- * Returns 0 on success, negative on error
- */
-int metalog_init(struct rrdengine_instance *rrdeng_parent_ctx)
-{
-    struct metalog_instance *ctx;
-    int error;
-
-    ctx = callocz(1, sizeof(*ctx));
-    ctx->initialized = 0;
-    rrdeng_parent_ctx->metalog_ctx = ctx;
-
-    ctx->rrdeng_ctx = rrdeng_parent_ctx;
-    error = init_metalog_files(ctx);
-    if (error) {
-        goto error_after_init_rrd_files;
-    }
-    ctx->initialized = 1; /* notify dbengine that the metadata log has finished initializing */
-    return 0;
-
-error_after_init_rrd_files:
-    freez(ctx);
-    return UV_EIO;
-}
-
-/* This function is called by dbengine rotation logic when the metric has no writers */
-void metalog_delete_dimension_by_uuid(struct metalog_instance *ctx, uuid_t *metric_uuid)
-{
-    uuid_t  multihost_uuid;
-
-    delete_dimension_uuid(metric_uuid);
-    rrdeng_convert_legacy_uuid_to_multihost(ctx->rrdeng_ctx->machine_guid, metric_uuid, &multihost_uuid);
-    delete_dimension_uuid(&multihost_uuid);
-}
diff --git a/database/engine/metadata_log/metadatalogapi.h b/database/engine/metadata_log/metadatalogapi.h
deleted file mode 100644
index d558b9317..000000000
--- a/database/engine/metadata_log/metadatalogapi.h
+++ /dev/null
@@ -1,12 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#ifndef NETDATA_METADATALOGAPI_H
-#define NETDATA_METADATALOGAPI_H
-
-extern void metalog_commit_delete_chart(RRDSET *st);
-extern void metalog_delete_dimension_by_uuid(struct metalog_instance *ctx, uuid_t *metric_uuid);
-
-/* must call once before using anything */
-extern int metalog_init(struct rrdengine_instance *rrdeng_parent_ctx);
-
-#endif /* NETDATA_METADATALOGAPI_H */
diff --git a/database/engine/metadata_log/metadatalogprotocol.h b/database/engine/metadata_log/metadatalogprotocol.h
deleted file mode 100644
index 1017213ae..000000000
--- a/database/engine/metadata_log/metadatalogprotocol.h
+++ /dev/null
@@ -1,53 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#ifndef NETDATA_METADATALOGPROTOCOL_H
-#define NETDATA_METADATALOGPROTOCOL_H
-
-#include "../rrddiskprotocol.h"
-
-#define RRDENG_METALOG_MAGIC "netdata-metadata-log"
-
-#define RRDENG_METALOG_VER (1)
-
-#define RRDENG_METALOG_SB_PADDING_SZ (RRDENG_BLOCK_SIZE - (RRDENG_MAGIC_SZ + sizeof(uint16_t)))
-/*
- * Metadata log persistent super-block
- */
-struct rrdeng_metalog_sb {
-    char magic_number[RRDENG_MAGIC_SZ];
-    uint16_t version;
-    uint8_t padding[RRDENG_METALOG_SB_PADDING_SZ];
-} __attribute__ ((packed));
-
-/*
- * Metadata log record types
- */
-#define METALOG_STORE_PADDING       (0)
-#define METALOG_CREATE_OBJECT       (1)
-#define METALOG_DELETE_OBJECT       (2)
-#define METALOG_OTHER               (3) /* reserved */
-
-/*
- * Metadata log record header
- */
-struct rrdeng_metalog_record_header {
-    /* when set to METALOG_STORE_PADDING jump to start of next block */
-    uint8_t type;
-
-    uint16_t header_length;
-    uint32_t payload_length;
-    /******************************************************
-     * No fields above this point can ever change.        *
-     ******************************************************
-     * All fields below this point are subject to change. *
-     ******************************************************/
-} __attribute__ ((packed));
-
-/*
- * Metadata log record trailer
- */
-struct rrdeng_metalog_record_trailer {
-    uint8_t checksum[CHECKSUM_SZ]; /* CRC32 */
-} __attribute__ ((packed));
-
-#endif /* NETDATA_METADATALOGPROTOCOL_H */
diff --git a/database/engine/metadata_log/metalogpluginsd.c b/database/engine/metadata_log/metalogpluginsd.c
deleted file mode 100755
index a5301bc10..000000000
--- a/database/engine/metadata_log/metalogpluginsd.c
+++ /dev/null
@@ -1,140 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-#define NETDATA_RRD_INTERNALS
-
-#include "metadatalog.h"
-#include "metalogpluginsd.h"
-
-extern struct config stream_config;
-
-PARSER_RC metalog_pluginsd_host_action(
-    void *user, char *machine_guid, char *hostname, char *registry_hostname, int update_every, char *os, char *timezone,
-    char *tags)
-{
-    struct metalog_pluginsd_state *state = ((PARSER_USER_OBJECT *)user)->private;
-
-    RRDHOST *host = rrdhost_find_by_guid(machine_guid, 0);
-    if (host) {
-        if (unlikely(host->rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)) {
-            error("Archived host '%s' has memory mode '%s', but the archived one is '%s'. Ignoring archived state.",
-                  host->hostname, rrd_memory_mode_name(host->rrd_memory_mode),
-                  rrd_memory_mode_name(RRD_MEMORY_MODE_DBENGINE));
-            ((PARSER_USER_OBJECT *) user)->host = NULL; /* Ignore objects if memory mode is not dbengine */
-        }
-        ((PARSER_USER_OBJECT *) user)->host = host;
-        return PARSER_RC_OK;
-    }
-
-    if (strcmp(machine_guid, registry_get_this_machine_guid()) == 0) {
-        ((PARSER_USER_OBJECT *) user)->host = host;
-        return PARSER_RC_OK;
-    }
-
-    if (likely(!uuid_parse(machine_guid, state->host_uuid))) {
-        int rc = sql_store_host(&state->host_uuid, hostname, registry_hostname, update_every, os, timezone, tags, 1);
-        if (unlikely(rc)) {
-            errno = 0;
-            error("Failed to store host %s with UUID %s in the database", hostname, machine_guid);
-        }
-    }
-    else {
-        errno = 0;
-        error("Host machine GUID %s is not valid", machine_guid);
-    }
-
-    return PARSER_RC_OK;
-}
-
-PARSER_RC metalog_pluginsd_chart_action(void *user, char *type, char *id, char *name, char *family, char *context,
-                                        char *title, char *units, char *plugin, char *module, int priority,
-                                        int update_every, RRDSET_TYPE chart_type, char *options)
-{
-    UNUSED(options);
-
-    struct metalog_pluginsd_state *state = ((PARSER_USER_OBJECT *)user)->private;
-    RRDHOST *host = ((PARSER_USER_OBJECT *) user)->host;
-
-    if (unlikely(uuid_is_null(state->host_uuid))) {
-        debug(D_METADATALOG, "Ignoring chart belonging to missing or ignored host.");
-        return PARSER_RC_OK;
-    }
-    uuid_copy(state->chart_uuid, state->uuid);
-    uuid_clear(state->uuid); /* Consume UUID */
-    (void) sql_store_chart(&state->chart_uuid, &state->host_uuid,
-        type, id, name, family, context, title, units,
-        plugin, module, priority, update_every,
-        chart_type, RRD_MEMORY_MODE_DBENGINE, host ? host->rrd_history_entries : 1);
-    ((PARSER_USER_OBJECT *)user)->st_exists = 1;
-
-    return PARSER_RC_OK;
-}
-
-PARSER_RC metalog_pluginsd_dimension_action(void *user, RRDSET *st, char *id, char *name, char *algorithm,
-                                            long multiplier, long divisor, char *options, RRD_ALGORITHM algorithm_type)
-{
-    struct metalog_pluginsd_state *state = ((PARSER_USER_OBJECT *)user)->private;
-    UNUSED(user);
-    UNUSED(options);
-    UNUSED(algorithm);
-    UNUSED(st);
-
-    if (unlikely(uuid_is_null(state->chart_uuid))) {
-        debug(D_METADATALOG, "Ignoring dimension belonging to missing or ignored chart.");
-        info("Ignoring dimension belonging to missing or ignored chart.");
-        return PARSER_RC_OK;
-    }
-
-    if (unlikely(uuid_is_null(state->uuid))) {
-        debug(D_METADATALOG, "Ignoring dimension without unknown UUID");
-        info("Ignoring dimension without unknown UUID");
-        return PARSER_RC_OK;
-    }
-
-    (void) sql_store_dimension(&state->uuid, &state->chart_uuid, id, name, multiplier, divisor, algorithm_type);
-    uuid_clear(state->uuid); /* Consume UUID */
-
-    return PARSER_RC_OK;
-}
-
-PARSER_RC metalog_pluginsd_guid_action(void *user, uuid_t *uuid)
-{
-    struct metalog_pluginsd_state *state = ((PARSER_USER_OBJECT *)user)->private;
-
-    uuid_copy(state->uuid, *uuid);
-
-    return PARSER_RC_OK;
-}
-
-PARSER_RC metalog_pluginsd_context_action(void *user, uuid_t *uuid)
-{
-    struct metalog_pluginsd_state *state = ((PARSER_USER_OBJECT *)user)->private;
-
-    int rc = find_uuid_type(uuid);
-
-    if (rc == 1) {
-        uuid_copy(state->host_uuid, *uuid);
-        ((PARSER_USER_OBJECT *)user)->st_exists = 0;
-        ((PARSER_USER_OBJECT *)user)->host_exists = 1;
-    } else if (rc == 2) {
-        uuid_copy(state->chart_uuid, *uuid);
-        ((PARSER_USER_OBJECT *)user)->st_exists = 1;
-    } else
-        uuid_copy(state->uuid, *uuid);
-
-    return PARSER_RC_OK;
-}
-
-PARSER_RC metalog_pluginsd_tombstone_action(void *user, uuid_t *uuid)
-{
-    UNUSED(user);
-    UNUSED(uuid);
-
-    return PARSER_RC_OK;
-}
-
-void metalog_pluginsd_state_init(struct metalog_pluginsd_state *state, struct metalog_instance *ctx)
-{
-    state->ctx = ctx;
-    state->skip_record = 0;
-    uuid_clear(state->uuid);
-    state->metalogfile = NULL;
-}
diff --git a/database/engine/metadata_log/metalogpluginsd.h b/database/engine/metadata_log/metalogpluginsd.h
deleted file mode 100644
index 4fd8c3900..000000000
--- a/database/engine/metadata_log/metalogpluginsd.h
+++ /dev/null
@@ -1,33 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#ifndef NETDATA_METALOGPLUGINSD_H
-#define NETDATA_METALOGPLUGINSD_H
-
-#include "collectors/plugins.d/pluginsd_parser.h"
-#include "collectors/plugins.d/plugins_d.h"
-#include "parser/parser.h"
-
-struct metalog_pluginsd_state {
-    struct metalog_instance *ctx;
-    uuid_t uuid;
-    uuid_t host_uuid;
-    uuid_t chart_uuid;
-    uint8_t skip_record; /* skip this record due to errors in parsing */
-    struct metadata_logfile *metalogfile; /* current metadata log file being replayed */
-};
-
-extern void metalog_pluginsd_state_init(struct metalog_pluginsd_state *state, struct metalog_instance *ctx);
-
-extern PARSER_RC metalog_pluginsd_chart_action(void *user, char *type, char *id, char *name, char *family,
-                                               char *context, char *title, char *units, char *plugin, char *module,
-                                               int priority, int update_every, RRDSET_TYPE chart_type, char *options);
-extern PARSER_RC metalog_pluginsd_dimension_action(void *user, RRDSET *st, char *id, char *name, char *algorithm,
-                                                   long multiplier, long divisor, char *options,
-                                                   RRD_ALGORITHM algorithm_type);
-extern PARSER_RC metalog_pluginsd_guid_action(void *user, uuid_t *uuid);
-extern PARSER_RC metalog_pluginsd_context_action(void *user, uuid_t *uuid);
-extern PARSER_RC metalog_pluginsd_tombstone_action(void *user, uuid_t *uuid);
-extern PARSER_RC metalog_pluginsd_host(char **words, void *user, PLUGINSD_ACTION  *plugins_action);
-extern PARSER_RC metalog_pluginsd_host_action(void *user, char *machine_guid, char *hostname, char *registry_hostname, int update_every, char *os, char *timezone, char *tags);
-
-#endif /* NETDATA_METALOGPLUGINSD_H */
diff --git a/database/engine/pagecache.c b/database/engine/pagecache.c
index 39f7642d0..d65cb35a5 100644
--- a/database/engine/pagecache.c
+++ b/database/engine/pagecache.c
@@ -4,8 +4,8 @@
 #include "rrdengine.h"
 
 ARAL page_descr_aral = {
-    .element_size = sizeof(struct rrdeng_page_descr),
-    .elements = 20000,
+    .requested_element_size = sizeof(struct rrdeng_page_descr),
+    .initial_elements = 20000,
     .filename = "page_descriptors",
     .cache_dir = &netdata_configured_cache_dir,
     .use_mmap = false,
@@ -127,12 +127,13 @@ struct rrdeng_page_descr *pg_cache_create_descr(void)
 
     descr = rrdeng_page_descr_mallocz();
     descr->page_length = 0;
-    descr->start_time = INVALID_TIME;
-    descr->end_time = INVALID_TIME;
+    descr->start_time_ut = INVALID_TIME;
+    descr->end_time_ut = INVALID_TIME;
     descr->id = NULL;
     descr->extent = NULL;
     descr->pg_cache_descr_state = 0;
     descr->pg_cache_descr = NULL;
+    descr->update_every_s = 0;
 
     return descr;
 }
@@ -476,7 +477,7 @@ uint8_t pg_cache_punch_hole(struct rrdengine_instance *ctx, struct rrdeng_page_d
     uv_rwlock_rdunlock(&pg_cache->metrics_index.lock);
 
     uv_rwlock_wrlock(&page_index->lock);
-    ret = JudyLDel(&page_index->JudyL_array, (Word_t)(descr->start_time / USEC_PER_SEC), PJE0);
+    ret = JudyLDel(&page_index->JudyL_array, (Word_t)(descr->start_time_ut / USEC_PER_SEC), PJE0);
     if (unlikely(0 == ret)) {
         uv_rwlock_wrunlock(&page_index->lock);
         if (unlikely(debug_flags & D_RRDENGINE)) {
@@ -506,7 +507,7 @@ uint8_t pg_cache_punch_hole(struct rrdengine_instance *ctx, struct rrdeng_page_d
         while (!pg_cache_try_get_unsafe(descr, 1)) {
             debug(D_RRDENGINE, "%s: Waiting for locked page:", __func__);
             if (unlikely(debug_flags & D_RRDENGINE))
-                print_page_cache_descr(descr);
+                print_page_cache_descr(descr, "", true);
             pg_cache_wait_event_unsafe(descr);
         }
     }
@@ -517,7 +518,7 @@ uint8_t pg_cache_punch_hole(struct rrdengine_instance *ctx, struct rrdeng_page_d
         while (unlikely(pg_cache_descr->flags & RRD_PAGE_DIRTY)) {
             debug(D_RRDENGINE, "%s: Found dirty page, waiting for it to be flushed:", __func__);
             if (unlikely(debug_flags & D_RRDENGINE))
-                print_page_cache_descr(descr);
+                print_page_cache_descr(descr, "", true);
             pg_cache_wait_event_unsafe(descr);
         }
     }
@@ -548,8 +549,8 @@ static inline int is_page_in_time_range(struct rrdeng_page_descr *descr, usec_t
 {
     usec_t pg_start, pg_end;
 
-    pg_start = descr->start_time;
-    pg_end = descr->end_time;
+    pg_start = descr->start_time_ut;
+    pg_end = descr->end_time_ut;
 
     return (pg_start < start_time && pg_end >= start_time) ||
            (pg_start >= start_time && pg_start <= end_time);
@@ -557,7 +558,7 @@ static inline int is_page_in_time_range(struct rrdeng_page_descr *descr, usec_t
 
 static inline int is_point_in_time_in_page(struct rrdeng_page_descr *descr, usec_t point_in_time)
 {
-    return (point_in_time >= descr->start_time && point_in_time <= descr->end_time);
+    return (point_in_time >= descr->start_time_ut && point_in_time <= descr->end_time_ut);
 }
 
 /* The caller must hold the page index lock */
@@ -592,14 +593,14 @@ static inline struct rrdeng_page_descr *
 /* Update metric oldest and latest timestamps efficiently when adding new values */
 void pg_cache_add_new_metric_time(struct pg_cache_page_index *page_index, struct rrdeng_page_descr *descr)
 {
-    usec_t oldest_time = page_index->oldest_time;
-    usec_t latest_time = page_index->latest_time;
+    usec_t oldest_time = page_index->oldest_time_ut;
+    usec_t latest_time = page_index->latest_time_ut;
 
-    if (unlikely(oldest_time == INVALID_TIME || descr->start_time < oldest_time)) {
-        page_index->oldest_time = descr->start_time;
+    if (unlikely(oldest_time == INVALID_TIME || descr->start_time_ut < oldest_time)) {
+        page_index->oldest_time_ut = descr->start_time_ut;
     }
-    if (likely(descr->end_time > latest_time || latest_time == INVALID_TIME)) {
-        page_index->latest_time = descr->end_time;
+    if (likely(descr->end_time_ut > latest_time || latest_time == INVALID_TIME)) {
+        page_index->latest_time_ut = descr->end_time_ut;
     }
 }
 
@@ -618,23 +619,23 @@ void pg_cache_update_metric_times(struct pg_cache_page_index *page_index)
     firstPValue = JudyLFirst(page_index->JudyL_array, &firstIndex, PJE0);
     if (likely(NULL != firstPValue)) {
         descr = *firstPValue;
-        oldest_time = descr->start_time;
+        oldest_time = descr->start_time_ut;
     }
     lastIndex = (Word_t)-1;
     lastPValue = JudyLLast(page_index->JudyL_array, &lastIndex, PJE0);
     if (likely(NULL != lastPValue)) {
         descr = *lastPValue;
-        latest_time = descr->end_time;
+        latest_time = descr->end_time_ut;
     }
     uv_rwlock_rdunlock(&page_index->lock);
 
     if (unlikely(NULL == firstPValue)) {
         fatal_assert(NULL == lastPValue);
-        page_index->oldest_time = page_index->latest_time = INVALID_TIME;
+        page_index->oldest_time_ut = page_index->latest_time_ut = INVALID_TIME;
         return;
     }
-    page_index->oldest_time = oldest_time;
-    page_index->latest_time = latest_time;
+    page_index->oldest_time_ut = oldest_time;
+    page_index->latest_time_ut = latest_time;
 }
 
 /* If index is NULL lookup by UUID (descr->id) */
@@ -669,7 +670,7 @@ void pg_cache_insert(struct rrdengine_instance *ctx, struct pg_cache_page_index
     }
 
     uv_rwlock_wrlock(&page_index->lock);
-    PValue = JudyLIns(&page_index->JudyL_array, (Word_t)(descr->start_time / USEC_PER_SEC), PJE0);
+    PValue = JudyLIns(&page_index->JudyL_array, (Word_t)(descr->start_time_ut / USEC_PER_SEC), PJE0);
     *PValue = descr;
     ++page_index->page_count;
     pg_cache_add_new_metric_time(page_index, descr);
@@ -681,7 +682,7 @@ void pg_cache_insert(struct rrdengine_instance *ctx, struct pg_cache_page_index
     uv_rwlock_wrunlock(&pg_cache->pg_cache_rwlock);
 }
 
-usec_t pg_cache_oldest_time_in_range(struct rrdengine_instance *ctx, uuid_t *id, usec_t start_time, usec_t end_time)
+usec_t pg_cache_oldest_time_in_range(struct rrdengine_instance *ctx, uuid_t *id, usec_t start_time_ut, usec_t end_time_ut)
 {
     struct page_cache *pg_cache = &ctx->pg_cache;
     struct rrdeng_page_descr *descr = NULL;
@@ -699,25 +700,25 @@ usec_t pg_cache_oldest_time_in_range(struct rrdengine_instance *ctx, uuid_t *id,
     }
 
     uv_rwlock_rdlock(&page_index->lock);
-    descr = find_first_page_in_time_range(page_index, start_time, end_time);
+    descr = find_first_page_in_time_range(page_index, start_time_ut, end_time_ut);
     if (NULL == descr) {
         uv_rwlock_rdunlock(&page_index->lock);
         return INVALID_TIME;
     }
     uv_rwlock_rdunlock(&page_index->lock);
-    return descr->start_time;
+    return descr->start_time_ut;
 }
 
 /**
  * Return page information for the first page before point_in_time that satisfies the filter.
  * @param ctx DB context
  * @param page_index page index of a metric
- * @param point_in_time the pages that are searched must be older than this timestamp
+ * @param point_in_time_ut the pages that are searched must be older than this timestamp
  * @param filter decides if the page satisfies the caller's criteria
  * @param page_info the result of the search is set in this pointer
  */
 void pg_cache_get_filtered_info_prev(struct rrdengine_instance *ctx, struct pg_cache_page_index *page_index,
-                                     usec_t point_in_time, pg_cache_page_info_filter_t *filter,
+                                     usec_t point_in_time_ut, pg_cache_page_info_filter_t *filter,
                                      struct rrdeng_page_info *page_info)
 {
     struct page_cache *pg_cache = &ctx->pg_cache;
@@ -728,7 +729,7 @@ void pg_cache_get_filtered_info_prev(struct rrdengine_instance *ctx, struct pg_c
     (void)pg_cache;
     fatal_assert(NULL != page_index);
 
-    Index = (Word_t)(point_in_time / USEC_PER_SEC);
+    Index = (Word_t)(point_in_time_ut / USEC_PER_SEC);
     uv_rwlock_rdlock(&page_index->lock);
     do {
         PValue = JudyLPrev(page_index->JudyL_array, &Index, PJE0);
@@ -736,12 +737,12 @@ void pg_cache_get_filtered_info_prev(struct rrdengine_instance *ctx, struct pg_c
     } while (descr != NULL && !filter(descr));
     if (unlikely(NULL == descr)) {
         page_info->page_length = 0;
-        page_info->start_time = INVALID_TIME;
-        page_info->end_time = INVALID_TIME;
+        page_info->start_time_ut = INVALID_TIME;
+        page_info->end_time_ut = INVALID_TIME;
     } else {
         page_info->page_length = descr->page_length;
-        page_info->start_time = descr->start_time;
-        page_info->end_time = descr->end_time;
+        page_info->start_time_ut = descr->start_time_ut;
+        page_info->end_time_ut = descr->end_time_ut;
     }
     uv_rwlock_rdunlock(&page_index->lock);
 }
@@ -750,7 +751,7 @@ void pg_cache_get_filtered_info_prev(struct rrdengine_instance *ctx, struct pg_c
  * Searches for an unallocated page without triggering disk I/O. Attempts to reserve the page and get a reference.
  * @param ctx DB context
  * @param id lookup by UUID
- * @param start_time exact starting time in usec
+ * @param start_time_ut exact starting time in usec
  * @param ret_page_indexp Sets the page index pointer (*ret_page_indexp) for the given UUID.
  * @return the page descriptor or NULL on failure. It can fail if:
  *         1. The page is already allocated to the page cache.
@@ -758,7 +759,7 @@ void pg_cache_get_filtered_info_prev(struct rrdengine_instance *ctx, struct pg_c
  *         3. It did not succeed to reserve a spot in the page cache.
  */
 struct rrdeng_page_descr *pg_cache_lookup_unpopulated_and_lock(struct rrdengine_instance *ctx, uuid_t *id,
-                                                               usec_t start_time)
+                                                               usec_t start_time_ut)
 {
     struct page_cache *pg_cache = &ctx->pg_cache;
     struct rrdeng_page_descr *descr = NULL;
@@ -781,7 +782,7 @@ struct rrdeng_page_descr *pg_cache_lookup_unpopulated_and_lock(struct rrdengine_
     }
 
     uv_rwlock_rdlock(&page_index->lock);
-    Index = (Word_t)(start_time / USEC_PER_SEC);
+    Index = (Word_t)(start_time_ut / USEC_PER_SEC);
     PValue = JudyLGet(page_index->JudyL_array, Index, PJE0);
     if (likely(NULL != PValue)) {
         descr = *PValue;
@@ -818,15 +819,15 @@ struct rrdeng_page_descr *pg_cache_lookup_unpopulated_and_lock(struct rrdengine_
  * Does not get a reference.
  * @param ctx DB context
  * @param id UUID
- * @param start_time inclusive starting time in usec
- * @param end_time inclusive ending time in usec
+ * @param start_time_ut inclusive starting time in usec
+ * @param end_time_ut inclusive ending time in usec
  * @param page_info_arrayp It allocates (*page_arrayp) and populates it with information of pages that overlap
  *        with the time range [start_time,end_time]. The caller must free (*page_info_arrayp) with freez().
  *        If page_info_arrayp is set to NULL nothing was allocated.
  * @param ret_page_indexp Sets the page index pointer (*ret_page_indexp) for the given UUID.
  * @return the number of pages that overlap with the time range [start_time,end_time].
  */
-unsigned pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t start_time, usec_t end_time,
+unsigned pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t start_time_ut, usec_t end_time_ut,
                           struct rrdeng_page_info **page_info_arrayp, struct pg_cache_page_index **ret_page_indexp)
 {
     struct page_cache *pg_cache = &ctx->pg_cache;
@@ -854,14 +855,14 @@ unsigned pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t sta
     }
 
     uv_rwlock_rdlock(&page_index->lock);
-    descr = find_first_page_in_time_range(page_index, start_time, end_time);
+    descr = find_first_page_in_time_range(page_index, start_time_ut, end_time_ut);
     if (NULL == descr) {
         uv_rwlock_rdunlock(&page_index->lock);
         debug(D_RRDENGINE, "%s: No page was found to attempt preload.", __func__);
         *ret_page_indexp = NULL;
         return 0;
     } else {
-        Index = (Word_t)(descr->start_time / USEC_PER_SEC);
+        Index = (Word_t)(descr->start_time_ut / USEC_PER_SEC);
     }
     if (page_info_arrayp) {
         page_info_array_max_size = PAGE_CACHE_MAX_PRELOAD_PAGES * sizeof(struct rrdeng_page_info);
@@ -869,7 +870,7 @@ unsigned pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t sta
     }
 
     for (count = 0, preload_count = 0 ;
-         descr != NULL && is_page_in_time_range(descr, start_time, end_time) ;
+         descr != NULL && is_page_in_time_range(descr, start_time_ut, end_time_ut) ;
          PValue = JudyLNext(page_index->JudyL_array, &Index, PJE0),
          descr = unlikely(NULL == PValue) ? NULL : *PValue) {
         /* Iterate all pages in range */
@@ -881,8 +882,8 @@ unsigned pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t sta
                 page_info_array_max_size += PAGE_CACHE_MAX_PRELOAD_PAGES * sizeof(struct rrdeng_page_info);
                 *page_info_arrayp = reallocz(*page_info_arrayp, page_info_array_max_size);
             }
-            (*page_info_arrayp)[count].start_time = descr->start_time;
-            (*page_info_arrayp)[count].end_time = descr->end_time;
+            (*page_info_arrayp)[count].start_time_ut = descr->start_time_ut;
+            (*page_info_arrayp)[count].end_time_ut = descr->end_time_ut;
             (*page_info_arrayp)[count].page_length = descr->page_length;
         }
         ++count;
@@ -974,7 +975,7 @@ unsigned pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t sta
  */
 struct rrdeng_page_descr *
         pg_cache_lookup(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, uuid_t *id,
-                        usec_t point_in_time)
+                        usec_t point_in_time_ut)
 {
     struct page_cache *pg_cache = &ctx->pg_cache;
     struct rrdeng_page_descr *descr = NULL;
@@ -1003,15 +1004,15 @@ struct rrdeng_page_descr *
     page_not_in_cache = 0;
     uv_rwlock_rdlock(&page_index->lock);
     while (1) {
-        Index = (Word_t)(point_in_time / USEC_PER_SEC);
+        Index = (Word_t)(point_in_time_ut / USEC_PER_SEC);
         PValue = JudyLLast(page_index->JudyL_array, &Index, PJE0);
         if (likely(NULL != PValue)) {
             descr = *PValue;
         }
         if (NULL == PValue ||
             0 == descr->page_length ||
-            (INVALID_TIME != point_in_time &&
-             !is_point_in_time_in_page(descr, point_in_time))) {
+            (INVALID_TIME != point_in_time_ut &&
+             !is_point_in_time_in_page(descr, point_in_time_ut))) {
             /* non-empty page not found */
             uv_rwlock_rdunlock(&page_index->lock);
 
@@ -1038,7 +1039,7 @@ struct rrdeng_page_descr *
 
             debug(D_RRDENGINE, "%s: Waiting for page to be asynchronously read from disk:", __func__);
             if(unlikely(debug_flags & D_RRDENGINE))
-                print_page_cache_descr(descr);
+                print_page_cache_descr(descr, "", true);
             while (!(pg_cache_descr->flags & RRD_PAGE_POPULATED)) {
                 pg_cache_wait_event_unsafe(descr);
             }
@@ -1053,7 +1054,7 @@ struct rrdeng_page_descr *
         uv_rwlock_rdunlock(&page_index->lock);
         debug(D_RRDENGINE, "%s: Waiting for page to be unlocked:", __func__);
         if(unlikely(debug_flags & D_RRDENGINE))
-            print_page_cache_descr(descr);
+            print_page_cache_descr(descr, "", true);
         if (!(flags & RRD_PAGE_POPULATED))
             page_not_in_cache = 1;
         pg_cache_wait_event_unsafe(descr);
@@ -1081,7 +1082,7 @@ struct rrdeng_page_descr *
  */
 struct rrdeng_page_descr *
 pg_cache_lookup_next(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, uuid_t *id,
-                     usec_t start_time, usec_t end_time)
+                     usec_t start_time_ut, usec_t end_time_ut)
 {
     struct page_cache *pg_cache = &ctx->pg_cache;
     struct rrdeng_page_descr *descr = NULL;
@@ -1110,7 +1111,7 @@ pg_cache_lookup_next(struct rrdengine_instance *ctx, struct pg_cache_page_index
     uv_rwlock_rdlock(&page_index->lock);
     int retry_count = 0;
     while (1) {
-        descr = find_first_page_in_time_range(page_index, start_time, end_time);
+        descr = find_first_page_in_time_range(page_index, start_time_ut, end_time_ut);
         if (NULL == descr || 0 == descr->page_length || retry_count == default_rrdeng_page_fetch_retries) {
             /* non-empty page not found */
             if (retry_count == default_rrdeng_page_fetch_retries)
@@ -1140,7 +1141,7 @@ pg_cache_lookup_next(struct rrdengine_instance *ctx, struct pg_cache_page_index
 
             debug(D_RRDENGINE, "%s: Waiting for page to be asynchronously read from disk:", __func__);
             if(unlikely(debug_flags & D_RRDENGINE))
-                print_page_cache_descr(descr);
+                print_page_cache_descr(descr, "", true);
             while (!(pg_cache_descr->flags & RRD_PAGE_POPULATED)) {
                 pg_cache_wait_event_unsafe(descr);
             }
@@ -1155,7 +1156,7 @@ pg_cache_lookup_next(struct rrdengine_instance *ctx, struct pg_cache_page_index
         uv_rwlock_rdunlock(&page_index->lock);
         debug(D_RRDENGINE, "%s: Waiting for page to be unlocked:", __func__);
         if(unlikely(debug_flags & D_RRDENGINE))
-            print_page_cache_descr(descr);
+            print_page_cache_descr(descr, "", true);
         if (!(flags & RRD_PAGE_POPULATED))
             page_not_in_cache = 1;
 
@@ -1180,7 +1181,7 @@ pg_cache_lookup_next(struct rrdengine_instance *ctx, struct pg_cache_page_index
     return descr;
 }
 
-struct pg_cache_page_index *create_page_index(uuid_t *id)
+struct pg_cache_page_index *create_page_index(uuid_t *id, struct rrdengine_instance *ctx)
 {
     struct pg_cache_page_index *page_index;
 
@@ -1188,11 +1189,15 @@ struct pg_cache_page_index *create_page_index(uuid_t *id)
     page_index->JudyL_array = (Pvoid_t) NULL;
     uuid_copy(page_index->id, *id);
     fatal_assert(0 == uv_rwlock_init(&page_index->lock));
-    page_index->oldest_time = INVALID_TIME;
-    page_index->latest_time = INVALID_TIME;
+    page_index->oldest_time_ut = INVALID_TIME;
+    page_index->latest_time_ut = INVALID_TIME;
     page_index->prev = NULL;
     page_index->page_count = 0;
+    page_index->refcount = 0;
     page_index->writers = 0;
+    page_index->ctx = ctx;
+    page_index->alignment = NULL;
+    page_index->latest_update_every_s = default_rrd_update_every;
 
     return page_index;
 }
@@ -1238,24 +1243,6 @@ void init_page_cache(struct rrdengine_instance *ctx)
     init_committed_page_index(ctx);
 }
 
-
-
-/*
- * METRIC                                            # number
- * 1. INDEX: JudyHS                                  # bytes
- * 2. DATA: page_index                               # bytes
- *
- * PAGE (1 page of 1 metric)                         # number
- * 1. INDEX AT METRIC: page_index->JudyL_array       # bytes
- * 2. DATA: descr                                    # bytes
- *
- * PAGE CACHE (1 page of 1 metric at the cache)      # number
- * 1. pg_cache_descr (if PG_CACHE_DESCR_ALLOCATED)   # bytes
- * 2. data (if RRD_PAGE_POPULATED)                   # bytes
- *
- */
-
-
 void free_page_cache(struct rrdengine_instance *ctx)
 {
     struct page_cache *pg_cache = &ctx->pg_cache;
@@ -1265,30 +1252,15 @@ void free_page_cache(struct rrdengine_instance *ctx)
     struct rrdeng_page_descr *descr;
     struct page_cache_descr *pg_cache_descr;
 
-    Word_t metrics_number      = 0,
-           metrics_bytes       = 0,
-           metrics_index_bytes = 0,
-           metrics_duration    = 0;
-
-    Word_t pages_number        = 0,
-           pages_bytes         = 0,
-           pages_index_bytes   = 0;
-
-    Word_t pages_size_per_type[256]  = { 0 },
-           pages_count_per_type[256] = { 0 };
-
-    Word_t cache_pages_number  = 0,
-           cache_pages_bytes   = 0,
-           cache_pages_data_bytes  = 0;
-
-    size_t points_in_db        = 0,
-           uncompressed_points_size = 0,
-           seconds_in_db       = 0,
-           single_point_pages  = 0;
-
-    Word_t pages_dirty_index_bytes = 0;
-
-    usec_t oldest_time_ut = LONG_MAX, latest_time_ut = 0;
+    // if we are exiting, the OS will recover all memory so do not slow down the shutdown process
+    // Do the cleanup if we are compiling with NETDATA_INTERNAL_CHECKS
+    // This affects the reporting of dbengine statistics which are available in real time
+    // via the /api/v1/dbengine_stats endpoint
+#ifndef NETDATA_DBENGINE_FREE
+    if (netdata_exit)
+        return;
+#endif
+    Word_t metrics_index_bytes = 0, pages_index_bytes = 0, pages_dirty_index_bytes = 0;
 
     /* Free committed page index */
     pages_dirty_index_bytes = JudyLFreeArray(&pg_cache->committed_page_index.JudyL_array, PJE0);
@@ -1305,116 +1277,30 @@ void free_page_cache(struct rrdengine_instance *ctx)
         PValue = JudyLFirst(page_index->JudyL_array, &Index, PJE0);
         descr = unlikely(NULL == PValue) ? NULL : *PValue;
 
-        size_t metric_duration = 0;
-        size_t metric_update_every = 0;
-        size_t metric_single_point_pages = 0;
-
         while (descr != NULL) {
             /* Iterate all page descriptors of this metric */
 
             if (descr->pg_cache_descr_state & PG_CACHE_DESCR_ALLOCATED) {
-                cache_pages_number++;
-
                 /* Check rrdenglocking.c */
                 pg_cache_descr = descr->pg_cache_descr;
                 if (pg_cache_descr->flags & RRD_PAGE_POPULATED) {
                     dbengine_page_free(pg_cache_descr->page);
-                    cache_pages_data_bytes += RRDENG_BLOCK_SIZE;
                 }
                 rrdeng_destroy_pg_cache_descr(ctx, pg_cache_descr);
-                cache_pages_bytes += sizeof(*pg_cache_descr);
             }
-
-            if(descr->start_time < oldest_time_ut)
-                oldest_time_ut = descr->start_time;
-
-            if(descr->end_time > latest_time_ut)
-                latest_time_ut = descr->end_time;
-
-            pages_size_per_type[descr->type] += descr->page_length;
-            pages_count_per_type[descr->type]++;
-
-            size_t points_in_page = (descr->page_length / PAGE_POINT_SIZE_BYTES(descr));
-            size_t page_duration  = ((descr->end_time - descr->start_time) / USEC_PER_SEC);
-            size_t update_every = (page_duration == 0) ? 1 : page_duration / (points_in_page - 1);
-
-            if (!page_duration && metric_update_every) {
-                page_duration = metric_update_every;
-                update_every = metric_update_every;
-            }
-            else if(page_duration)
-                metric_update_every = update_every;
-
-            uncompressed_points_size += descr->page_length;
-
-            if(page_duration > 0) {
-                page_duration = update_every * points_in_page;
-                metric_duration += page_duration;
-                seconds_in_db += page_duration;
-                points_in_db += descr->page_length / PAGE_POINT_SIZE_BYTES(descr);
-            }
-            else
-                metric_single_point_pages++;
-
             rrdeng_page_descr_freez(descr);
-            pages_bytes += sizeof(*descr);
-            pages_number++;
 
             PValue = JudyLNext(page_index->JudyL_array, &Index, PJE0);
             descr = unlikely(NULL == PValue) ? NULL : *PValue;
         }
 
-        if(metric_single_point_pages && metric_update_every) {
-            points_in_db += metric_single_point_pages;
-            seconds_in_db += metric_update_every * metric_single_point_pages;
-            metric_duration += metric_update_every * metric_single_point_pages;
-        }
-        else
-            single_point_pages += metric_single_point_pages;
-
         /* Free page index */
         pages_index_bytes += JudyLFreeArray(&page_index->JudyL_array, PJE0);
         fatal_assert(NULL == page_index->JudyL_array);
         freez(page_index);
-
-        metrics_number++;
-        metrics_bytes += sizeof(*page_index);
-        metrics_duration += metric_duration;
     }
     /* Free metrics index */
     metrics_index_bytes = JudyHSFreeArray(&pg_cache->metrics_index.JudyHS_array, PJE0);
     fatal_assert(NULL == pg_cache->metrics_index.JudyHS_array);
-
-    if(!metrics_number) metrics_number = 1;
-    if(!pages_number) pages_number = 1;
-    if(!cache_pages_number) cache_pages_number = 1;
-    if(!points_in_db) points_in_db = 1;
-    if(latest_time_ut == oldest_time_ut) oldest_time_ut -= USEC_PER_SEC;
-
-    if(single_point_pages) {
-        long double avg_duration = (long double)seconds_in_db / points_in_db;
-        points_in_db += single_point_pages;
-        seconds_in_db += (size_t)(avg_duration * single_point_pages);
-    }
-
-    info("DBENGINE STATISTICS ON METRICS:"
-         " Metrics: %lu (structures %lu bytes - per metric %0.2f, index (HS) %lu bytes - per metric %0.2f bytes - duration %zu secs) |"
-         " Page descriptors: %lu (structures %lu bytes - per page %0.2f bytes, index (L) %lu bytes - per page %0.2f, dirty index %lu bytes). |"
-         " Page cache: %lu pages (structures %lu bytes - per page %0.2f bytes, data %lu bytes). |"
-         " Points in db %zu, uncompressed size of points database %zu bytes. |"
-         " Duration of all points %zu seconds, average point duration %0.2f seconds."
-         " Duration of the database %llu seconds, average metric duration %0.2f seconds, average metric lifetime %0.2f%%."
-         , metrics_number, metrics_bytes, (double)metrics_bytes/metrics_number, metrics_index_bytes, (double)metrics_index_bytes/metrics_number, metrics_duration
-         , pages_number, pages_bytes, (double)pages_bytes/pages_number, pages_index_bytes, (double)pages_index_bytes/pages_number, pages_dirty_index_bytes
-         , cache_pages_number, cache_pages_bytes, (double)cache_pages_bytes/cache_pages_number, cache_pages_data_bytes
-         , points_in_db, uncompressed_points_size
-         , seconds_in_db, (double)seconds_in_db/points_in_db
-         , (latest_time_ut - oldest_time_ut) / USEC_PER_SEC, (double)metrics_duration/metrics_number
-         , (double)metrics_duration/metrics_number * 100.0 / ((latest_time_ut - oldest_time_ut) / USEC_PER_SEC)
-         );
-
-    for(int i = 0; i < 256 ;i++) {
-        if(pages_count_per_type[i])
-            info("DBENGINE STATISTICS ON PAGE TYPES: page type %d total pages %lu, average page size %0.2f bytes", i, pages_count_per_type[i], (double)pages_size_per_type[i]/pages_count_per_type[i]);
-    }
+    info("Freed %lu bytes of memory from page cache.", pages_dirty_index_bytes + pages_index_bytes + metrics_index_bytes);
 }
diff --git a/database/engine/pagecache.h b/database/engine/pagecache.h
index b938b9e05..2f4d6b332 100644
--- a/database/engine/pagecache.h
+++ b/database/engine/pagecache.h
@@ -60,18 +60,19 @@ struct rrdeng_page_descr {
     volatile unsigned long pg_cache_descr_state;
 
     /* page information */
-    usec_t start_time;
-    usec_t end_time;
-    uint32_t page_length;
+    usec_t start_time_ut;
+    usec_t end_time_ut;
+    uint32_t update_every_s:24;
     uint8_t type;
+    uint32_t page_length;
 };
 
 #define PAGE_INFO_SCRATCH_SZ (8)
 struct rrdeng_page_info {
     uint8_t scratch[PAGE_INFO_SCRATCH_SZ]; /* scratch area to be used by page-cache users */
 
-    usec_t start_time;
-    usec_t end_time;
+    usec_t start_time_ut;
+    usec_t end_time_ut;
     uint32_t page_length;
 };
 
@@ -80,6 +81,11 @@ typedef int pg_cache_page_info_filter_t(struct rrdeng_page_descr *);
 
 #define PAGE_CACHE_MAX_PRELOAD_PAGES    (256)
 
+struct pg_alignment {
+    uint32_t page_length;
+    uint32_t refcount;
+};
+
 /* maps time ranges to pages */
 struct pg_cache_page_index {
     uuid_t id;
@@ -89,6 +95,7 @@ struct pg_cache_page_index {
      */
     Pvoid_t JudyL_array;
     Word_t page_count;
+    unsigned short refcount;
     unsigned short writers;
     uv_rwlock_t lock;
 
@@ -96,13 +103,17 @@ struct pg_cache_page_index {
      * Only one effective writer, data deletion workqueue.
      * It's also written during the DB loading phase.
      */
-    usec_t oldest_time;
+    usec_t oldest_time_ut;
 
     /*
      * Only one effective writer, data collection thread.
      * It's also written by the data deletion workqueue when data collection is disabled for this metric.
      */
-    usec_t latest_time;
+    usec_t latest_time_ut;
+
+    struct rrdengine_instance *ctx;
+    struct pg_alignment *alignment;
+    uint32_t latest_update_every_s;
 
     struct pg_cache_page_index *prev;
 };
@@ -152,93 +163,93 @@ struct page_cache { /* TODO: add statistics */
     unsigned populated_pages;
 };
 
-extern void pg_cache_wake_up_waiters_unsafe(struct rrdeng_page_descr *descr);
-extern void pg_cache_wake_up_waiters(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
-extern void pg_cache_wait_event_unsafe(struct rrdeng_page_descr *descr);
-extern unsigned long pg_cache_wait_event(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
-extern void pg_cache_replaceQ_insert(struct rrdengine_instance *ctx,
+void pg_cache_wake_up_waiters_unsafe(struct rrdeng_page_descr *descr);
+void pg_cache_wake_up_waiters(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
+void pg_cache_wait_event_unsafe(struct rrdeng_page_descr *descr);
+unsigned long pg_cache_wait_event(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
+void pg_cache_replaceQ_insert(struct rrdengine_instance *ctx,
                                      struct rrdeng_page_descr *descr);
-extern void pg_cache_replaceQ_delete(struct rrdengine_instance *ctx,
+void pg_cache_replaceQ_delete(struct rrdengine_instance *ctx,
                                      struct rrdeng_page_descr *descr);
-extern void pg_cache_replaceQ_set_hot(struct rrdengine_instance *ctx,
+void pg_cache_replaceQ_set_hot(struct rrdengine_instance *ctx,
                                       struct rrdeng_page_descr *descr);
-extern struct rrdeng_page_descr *pg_cache_create_descr(void);
-extern int pg_cache_try_get_unsafe(struct rrdeng_page_descr *descr, int exclusive_access);
-extern void pg_cache_put_unsafe(struct rrdeng_page_descr *descr);
-extern void pg_cache_put(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
-extern void pg_cache_insert(struct rrdengine_instance *ctx, struct pg_cache_page_index *index,
+struct rrdeng_page_descr *pg_cache_create_descr(void);
+int pg_cache_try_get_unsafe(struct rrdeng_page_descr *descr, int exclusive_access);
+void pg_cache_put_unsafe(struct rrdeng_page_descr *descr);
+void pg_cache_put(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
+void pg_cache_insert(struct rrdengine_instance *ctx, struct pg_cache_page_index *index,
                             struct rrdeng_page_descr *descr);
-extern uint8_t pg_cache_punch_hole(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr,
+uint8_t pg_cache_punch_hole(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr,
                                    uint8_t remove_dirty, uint8_t is_exclusive_holder, uuid_t *metric_id);
-extern usec_t pg_cache_oldest_time_in_range(struct rrdengine_instance *ctx, uuid_t *id,
-                                            usec_t start_time, usec_t end_time);
-extern void pg_cache_get_filtered_info_prev(struct rrdengine_instance *ctx, struct pg_cache_page_index *page_index,
-                                            usec_t point_in_time, pg_cache_page_info_filter_t *filter,
+usec_t pg_cache_oldest_time_in_range(struct rrdengine_instance *ctx, uuid_t *id,
+                                            usec_t start_time_ut, usec_t end_time_ut);
+void pg_cache_get_filtered_info_prev(struct rrdengine_instance *ctx, struct pg_cache_page_index *page_index,
+                                            usec_t point_in_time_ut, pg_cache_page_info_filter_t *filter,
                                             struct rrdeng_page_info *page_info);
-extern struct rrdeng_page_descr *pg_cache_lookup_unpopulated_and_lock(struct rrdengine_instance *ctx, uuid_t *id,
-                                                                      usec_t start_time);
-extern unsigned
-        pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t start_time, usec_t end_time,
+struct rrdeng_page_descr *pg_cache_lookup_unpopulated_and_lock(struct rrdengine_instance *ctx, uuid_t *id,
+                                                                      usec_t start_time_ut);
+unsigned
+        pg_cache_preload(struct rrdengine_instance *ctx, uuid_t *id, usec_t start_time_ut, usec_t end_time_ut,
                          struct rrdeng_page_info **page_info_arrayp, struct pg_cache_page_index **ret_page_indexp);
-extern struct rrdeng_page_descr *
+struct rrdeng_page_descr *
         pg_cache_lookup(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, uuid_t *id,
-                        usec_t point_in_time);
-extern struct rrdeng_page_descr *
+                        usec_t point_in_time_ut);
+struct rrdeng_page_descr *
         pg_cache_lookup_next(struct rrdengine_instance *ctx, struct pg_cache_page_index *index, uuid_t *id,
-                     usec_t start_time, usec_t end_time);
-extern struct pg_cache_page_index *create_page_index(uuid_t *id);
-extern void init_page_cache(struct rrdengine_instance *ctx);
-extern void free_page_cache(struct rrdengine_instance *ctx);
-extern void pg_cache_add_new_metric_time(struct pg_cache_page_index *page_index, struct rrdeng_page_descr *descr);
-extern void pg_cache_update_metric_times(struct pg_cache_page_index *page_index);
-extern unsigned long pg_cache_hard_limit(struct rrdengine_instance *ctx);
-extern unsigned long pg_cache_soft_limit(struct rrdengine_instance *ctx);
-extern unsigned long pg_cache_committed_hard_limit(struct rrdengine_instance *ctx);
-
-extern void rrdeng_page_descr_aral_go_singlethreaded(void);
-extern void rrdeng_page_descr_aral_go_multithreaded(void);
-extern void rrdeng_page_descr_use_malloc(void);
-extern void rrdeng_page_descr_use_mmap(void);
-extern bool rrdeng_page_descr_is_mmap(void);
-extern struct rrdeng_page_descr *rrdeng_page_descr_mallocz(void);
-extern void rrdeng_page_descr_freez(struct rrdeng_page_descr *descr);
+                     usec_t start_time_ut, usec_t end_time_ut);
+struct pg_cache_page_index *create_page_index(uuid_t *id, struct rrdengine_instance *ctx);
+void init_page_cache(struct rrdengine_instance *ctx);
+void free_page_cache(struct rrdengine_instance *ctx);
+void pg_cache_add_new_metric_time(struct pg_cache_page_index *page_index, struct rrdeng_page_descr *descr);
+void pg_cache_update_metric_times(struct pg_cache_page_index *page_index);
+unsigned long pg_cache_hard_limit(struct rrdengine_instance *ctx);
+unsigned long pg_cache_soft_limit(struct rrdengine_instance *ctx);
+unsigned long pg_cache_committed_hard_limit(struct rrdengine_instance *ctx);
+
+void rrdeng_page_descr_aral_go_singlethreaded(void);
+void rrdeng_page_descr_aral_go_multithreaded(void);
+void rrdeng_page_descr_use_malloc(void);
+void rrdeng_page_descr_use_mmap(void);
+bool rrdeng_page_descr_is_mmap(void);
+struct rrdeng_page_descr *rrdeng_page_descr_mallocz(void);
+void rrdeng_page_descr_freez(struct rrdeng_page_descr *descr);
 
 static inline void
-    pg_cache_atomic_get_pg_info(struct rrdeng_page_descr *descr, usec_t *end_timep, uint32_t *page_lengthp)
+    pg_cache_atomic_get_pg_info(struct rrdeng_page_descr *descr, usec_t *end_time_ut_p, uint32_t *page_lengthp)
 {
-    usec_t end_time, old_end_time;
+    usec_t end_time_ut, old_end_time_ut;
     uint32_t page_length;
 
     if (NULL == descr->extent) {
         /* this page is currently being modified, get consistent info locklessly */
         do {
-            end_time = descr->end_time;
+            end_time_ut = descr->end_time_ut;
             __sync_synchronize();
-            old_end_time = end_time;
+            old_end_time_ut = end_time_ut;
             page_length = descr->page_length;
             __sync_synchronize();
-            end_time = descr->end_time;
+            end_time_ut = descr->end_time_ut;
             __sync_synchronize();
-        } while ((end_time != old_end_time || (end_time & 1) != 0));
+        } while ((end_time_ut != old_end_time_ut || (end_time_ut & 1) != 0));
 
-        *end_timep = end_time;
+        *end_time_ut_p = end_time_ut;
         *page_lengthp = page_length;
     } else {
-        *end_timep = descr->end_time;
+        *end_time_ut_p = descr->end_time_ut;
         *page_lengthp = descr->page_length;
     }
 }
 
 /* The caller must hold a reference to the page and must have already set the new data */
-static inline void pg_cache_atomic_set_pg_info(struct rrdeng_page_descr *descr, usec_t end_time, uint32_t page_length)
+static inline void pg_cache_atomic_set_pg_info(struct rrdeng_page_descr *descr, usec_t end_time_ut, uint32_t page_length)
 {
-    fatal_assert(!(end_time & 1));
+    fatal_assert(!(end_time_ut & 1));
     __sync_synchronize();
-    descr->end_time |= 1; /* mark start of uncertainty period by adding 1 microsecond */
+    descr->end_time_ut |= 1; /* mark start of uncertainty period by adding 1 microsecond */
     __sync_synchronize();
     descr->page_length = page_length;
     __sync_synchronize();
-    descr->end_time = end_time; /* mark end of uncertainty period */
+    descr->end_time_ut = end_time_ut; /* mark end of uncertainty period */
 }
 
 #endif /* NETDATA_PAGECACHE_H */
diff --git a/database/engine/rrddiskprotocol.h b/database/engine/rrddiskprotocol.h
index cb57385a4..5b4be9498 100644
--- a/database/engine/rrddiskprotocol.h
+++ b/database/engine/rrddiskprotocol.h
@@ -46,8 +46,8 @@ struct rrdeng_extent_page_descr {
 
     uint8_t uuid[UUID_SZ];
     uint32_t page_length;
-    uint64_t start_time;
-    uint64_t end_time;
+    uint64_t start_time_ut;
+    uint64_t end_time_ut;
 } __attribute__ ((packed));
 
 /*
diff --git a/database/engine/rrdengine.c b/database/engine/rrdengine.c
index 8b35051d8..e4cd37e98 100644
--- a/database/engine/rrdengine.c
+++ b/database/engine/rrdengine.c
@@ -30,7 +30,7 @@ void dbengine_page_free(void *page) {
     if (unlikely(db_engine_use_malloc))
         freez(page);
     else
-        munmap(page, RRDENG_BLOCK_SIZE);
+        netdata_munmap(page, RRDENG_BLOCK_SIZE);
 }
 
 static void sanity_check(void)
@@ -206,8 +206,8 @@ void read_cached_extent_cb(struct rrdengine_worker_config* wc, unsigned idx, str
             /* care, we don't hold the descriptor mutex */
             if (!uuid_compare(*extent->pages[j]->id, *descr->id) &&
                 extent->pages[j]->page_length == descr->page_length &&
-                extent->pages[j]->start_time == descr->start_time &&
-                extent->pages[j]->end_time == descr->end_time) {
+                extent->pages[j]->start_time_ut == descr->start_time_ut &&
+                extent->pages[j]->end_time_ut == descr->end_time_ut) {
                 break;
             }
             page_offset += extent->pages[j]->page_length;
@@ -272,11 +272,9 @@ static void fill_page_with_nulls(void *page, uint32_t page_length, uint8_t type)
     }
 }
 
-void read_extent_cb(uv_fs_t* req)
+static void do_extent_processing (struct rrdengine_worker_config *wc, struct extent_io_descriptor *xt_io_descr, bool read_failed)
 {
-    struct rrdengine_worker_config* wc = req->loop->data;
     struct rrdengine_instance *ctx = wc->ctx;
-    struct extent_io_descriptor *xt_io_descr;
     struct rrdeng_page_descr *descr;
     struct page_cache_descr *pg_cache_descr;
     int ret;
@@ -289,21 +287,20 @@ void read_extent_cb(uv_fs_t* req)
     struct rrdeng_df_extent_trailer *trailer;
     uLong crc;
 
-    xt_io_descr = req->data;
     header = xt_io_descr->buf;
     payload_length = header->payload_length;
     count = header->number_of_pages;
     payload_offset = sizeof(*header) + sizeof(header->descr[0]) * count;
     trailer = xt_io_descr->buf + xt_io_descr->bytes - sizeof(*trailer);
 
-    if (req->result < 0) {
+    if (unlikely(read_failed)) {
         struct rrdengine_datafile *datafile = xt_io_descr->descr_array[0]->extent->datafile;
 
         ++ctx->stats.io_errors;
         rrd_stat_atomic_add(&global_io_errors, 1);
         have_read_error = 1;
-        error("%s: uv_fs_read - %s - extent at offset %"PRIu64"(%u) in datafile %u-%u.", __func__,
-              uv_strerror((int)req->result), xt_io_descr->pos, xt_io_descr->bytes, datafile->tier, datafile->fileno);
+        error("%s: uv_fs_read - extent at offset %"PRIu64"(%u) in datafile %u-%u.", __func__, xt_io_descr->pos,
+              xt_io_descr->bytes, datafile->tier, datafile->fileno);
         goto after_crc_check;
     }
     crc = crc32(0L, Z_NULL, 0);
@@ -378,8 +375,8 @@ after_crc_check:
             /* care, we don't hold the descriptor mutex */
             if (!uuid_compare(*(uuid_t *) header->descr[i].uuid, *descrj->id) &&
                 header->descr[i].page_length == descrj->page_length &&
-                header->descr[i].start_time == descrj->start_time &&
-                header->descr[i].end_time == descrj->end_time) {
+                header->descr[i].start_time_ut == descrj->start_time_ut &&
+                header->descr[i].end_time_ut == descrj->end_time_ut) {
                 descr = descrj;
                 break;
             }
@@ -387,7 +384,7 @@ after_crc_check:
         is_prefetched_page = 0;
         if (!descr) { /* This extent page has not been requested. Try populating it for locality (best effort). */
             descr = pg_cache_lookup_unpopulated_and_lock(ctx, (uuid_t *)header->descr[i].uuid,
-                                                         header->descr[i].start_time);
+                                                         header->descr[i].start_time_ut);
             if (!descr)
                 continue; /* Failed to reserve a suitable page */
             is_prefetched_page = 1;
@@ -421,11 +418,67 @@ after_crc_check:
     }
     if (xt_io_descr->completion)
         completion_mark_complete(xt_io_descr->completion);
+}
+
+static void read_extent_cb(uv_fs_t *req)
+{
+    struct rrdengine_worker_config *wc = req->loop->data;
+    struct extent_io_descriptor *xt_io_descr;
+
+    xt_io_descr = req->data;
+    do_extent_processing(wc, xt_io_descr, req->result < 0);
     uv_fs_req_cleanup(req);
-    free(xt_io_descr->buf);
+    posix_memfree(xt_io_descr->buf);
     freez(xt_io_descr);
 }
 
+static void read_mmap_extent_cb(uv_work_t *req, int status __maybe_unused)
+{
+    struct rrdengine_worker_config *wc = req->loop->data;
+    struct rrdengine_instance *ctx = wc->ctx;
+    struct extent_io_descriptor *xt_io_descr;
+    xt_io_descr = req->data;
+
+    if (likely(xt_io_descr->map_base)) {
+        do_extent_processing(wc, xt_io_descr, false);
+        munmap(xt_io_descr->map_base, xt_io_descr->map_length);
+        freez(xt_io_descr);
+        return;
+    }
+
+    // MMAP failed, so do uv_fs_read
+    int ret = posix_memalign((void *)&xt_io_descr->buf, RRDFILE_ALIGNMENT, ALIGN_BYTES_CEILING(xt_io_descr->bytes));
+    if (unlikely(ret)) {
+        fatal("posix_memalign:%s", strerror(ret));
+    }
+    unsigned real_io_size = ALIGN_BYTES_CEILING( xt_io_descr->bytes);
+    xt_io_descr->iov = uv_buf_init((void *)xt_io_descr->buf, real_io_size);
+    xt_io_descr->req.data = xt_io_descr;
+    ret = uv_fs_read(req->loop, &xt_io_descr->req, xt_io_descr->file, &xt_io_descr->iov, 1, (unsigned) xt_io_descr->pos, read_extent_cb);
+    fatal_assert(-1 != ret);
+    ctx->stats.io_read_bytes += real_io_size;
+    ctx->stats.io_read_extent_bytes += real_io_size;
+}
+
+static void do_mmap_read_extent(uv_work_t *req)
+{
+    struct extent_io_descriptor *xt_io_descr = (struct extent_io_descriptor * )req->data;
+    struct rrdengine_worker_config *wc = req->loop->data;
+    struct rrdengine_instance *ctx = wc->ctx;
+
+    off_t map_start =  ALIGN_BYTES_FLOOR(xt_io_descr->pos);
+    size_t length = ALIGN_BYTES_CEILING(xt_io_descr->pos + xt_io_descr->bytes) - map_start;
+    unsigned real_io_size = xt_io_descr->bytes;
+
+    void *data = mmap(NULL, length, PROT_READ, MAP_SHARED, xt_io_descr->file, map_start);
+    if (likely(data != MAP_FAILED)) {
+        xt_io_descr->map_base = data;
+        xt_io_descr->map_length = length;
+        xt_io_descr->buf = data + (xt_io_descr->pos - map_start);
+        ctx->stats.io_read_bytes += real_io_size;
+        ctx->stats.io_read_extent_bytes += real_io_size;
+    }
+}
 
 static void do_read_extent(struct rrdengine_worker_config* wc,
                            struct rrdeng_page_descr **descr,
@@ -435,8 +488,7 @@ static void do_read_extent(struct rrdengine_worker_config* wc,
     struct rrdengine_instance *ctx = wc->ctx;
     struct page_cache_descr *pg_cache_descr;
     int ret;
-    unsigned i, size_bytes, pos, real_io_size;
-//    uint32_t payload_length;
+    unsigned i, size_bytes, pos;
     struct extent_io_descriptor *xt_io_descr;
     struct rrdengine_datafile *datafile;
     struct extent_info *extent = descr[0]->extent;
@@ -452,18 +504,17 @@ static void do_read_extent(struct rrdengine_worker_config* wc,
         rrdeng_page_descr_mutex_lock(ctx, descr[i]);
         pg_cache_descr = descr[i]->pg_cache_descr;
         pg_cache_descr->flags |= RRD_PAGE_READ_PENDING;
-//        payload_length = descr[i]->page_length;
         rrdeng_page_descr_mutex_unlock(ctx, descr[i]);
-
         xt_io_descr->descr_array[i] = descr[i];
     }
     xt_io_descr->descr_count = count;
+    xt_io_descr->file = datafile->file;
     xt_io_descr->bytes = size_bytes;
     xt_io_descr->pos = pos;
-    xt_io_descr->req.data = xt_io_descr;
+    xt_io_descr->req_worker.data = xt_io_descr;
     xt_io_descr->completion = NULL;
-    /* xt_io_descr->descr_commit_idx_array[0] */
     xt_io_descr->release_descr = release_descr;
+    xt_io_descr->buf = NULL;
 
     xt_is_cached = !lookup_in_xt_cache(wc, extent, &xt_idx);
     if (xt_is_cached) {
@@ -483,19 +534,10 @@ static void do_read_extent(struct rrdengine_worker_config* wc,
         }
     }
 
-    ret = posix_memalign((void *)&xt_io_descr->buf, RRDFILE_ALIGNMENT, ALIGN_BYTES_CEILING(size_bytes));
-    if (unlikely(ret)) {
-        fatal("posix_memalign:%s", strerror(ret));
-        /* freez(xt_io_descr);
-    return;*/
-    }
-    real_io_size = ALIGN_BYTES_CEILING(size_bytes);
-    xt_io_descr->iov = uv_buf_init((void *)xt_io_descr->buf, real_io_size);
-    ret = uv_fs_read(wc->loop, &xt_io_descr->req, datafile->file, &xt_io_descr->iov, 1, pos, read_extent_cb);
+    ret = uv_queue_work(wc->loop, &xt_io_descr->req_worker, do_mmap_read_extent, read_mmap_extent_cb);
     fatal_assert(-1 != ret);
-    ctx->stats.io_read_bytes += real_io_size;
+
     ++ctx->stats.io_read_requests;
-    ctx->stats.io_read_extent_bytes += real_io_size;
     ++ctx->stats.io_read_extents;
     ctx->stats.pg_cache_backfills += count;
 }
@@ -696,7 +738,7 @@ void flush_pages_cb(uv_fs_t* req)
     if (xt_io_descr->completion)
         completion_mark_complete(xt_io_descr->completion);
     uv_fs_req_cleanup(req);
-    free(xt_io_descr->buf);
+    posix_memfree(xt_io_descr->buf);
     freez(xt_io_descr);
 
     uv_rwlock_wrlock(&pg_cache->committed_page_index.lock);
@@ -820,8 +862,8 @@ static int do_flush_pages(struct rrdengine_worker_config* wc, int force, struct
         header->descr[i].type = descr->type;
         uuid_copy(*(uuid_t *)header->descr[i].uuid, *descr->id);
         header->descr[i].page_length = descr->page_length;
-        header->descr[i].start_time = descr->start_time;
-        header->descr[i].end_time = descr->end_time;
+        header->descr[i].start_time_ut = descr->start_time_ut;
+        header->descr[i].end_time_ut = descr->end_time_ut;
         pos += sizeof(header->descr[i]);
     }
     for (i = 0 ; i < count ; ++i) {
@@ -922,7 +964,6 @@ static void after_delete_old_data(struct rrdengine_worker_config* wc)
     wc->now_deleting_files = NULL;
 
     wc->cleanup_thread_deleting_files = 0;
-    aclk_data_rotated();
     rrdcontext_db_rotation();
 
     /* interrupt event loop */
@@ -948,12 +989,12 @@ static void delete_old_data(void *arg)
         for (i = 0 ; i < count ; ++i) {
             descr = extent->pages[i];
             can_delete_metric = pg_cache_punch_hole(ctx, descr, 0, 0, &metric_id);
-            if (unlikely(can_delete_metric && ctx->metalog_ctx->initialized)) {
+            if (unlikely(can_delete_metric)) {
                 /*
                  * If the metric is empty, has no active writers and if the metadata log has been initialized then
                  * attempt to delete the corresponding netdata dimension.
                  */
-                metalog_delete_dimension_by_uuid(ctx->metalog_ctx, &metric_id);
+                metaqueue_delete_dimension_uuid(&metric_id);
             }
         }
         next = extent->next;
@@ -1044,7 +1085,70 @@ static void rrdeng_cleanup_finished_threads(struct rrdengine_worker_config* wc)
 /* return 0 on success */
 int init_rrd_files(struct rrdengine_instance *ctx)
 {
-    return init_data_files(ctx);
+    int ret = init_data_files(ctx);
+
+    BUFFER *wb = buffer_create(1000);
+    size_t all_errors = 0;
+    usec_t now = now_realtime_usec();
+
+    if(ctx->load_errors[LOAD_ERRORS_PAGE_FLIPPED_TIME].counter) {
+        buffer_sprintf(wb, "%s%zu pages had start time > end time (latest: %llu secs ago)"
+                       , (all_errors)?", ":""
+                       , ctx->load_errors[LOAD_ERRORS_PAGE_FLIPPED_TIME].counter
+                       , (now - ctx->load_errors[LOAD_ERRORS_PAGE_FLIPPED_TIME].latest_end_time_ut) / USEC_PER_SEC
+                       );
+        all_errors += ctx->load_errors[LOAD_ERRORS_PAGE_FLIPPED_TIME].counter;
+    }
+
+    if(ctx->load_errors[LOAD_ERRORS_PAGE_EQUAL_TIME].counter) {
+        buffer_sprintf(wb, "%s%zu pages had start time = end time with more than 1 entries (latest: %llu secs ago)"
+                       , (all_errors)?", ":""
+                       , ctx->load_errors[LOAD_ERRORS_PAGE_EQUAL_TIME].counter
+                       , (now - ctx->load_errors[LOAD_ERRORS_PAGE_EQUAL_TIME].latest_end_time_ut) / USEC_PER_SEC
+        );
+        all_errors += ctx->load_errors[LOAD_ERRORS_PAGE_EQUAL_TIME].counter;
+    }
+
+    if(ctx->load_errors[LOAD_ERRORS_PAGE_ZERO_ENTRIES].counter) {
+        buffer_sprintf(wb, "%s%zu pages had zero points (latest: %llu secs ago)"
+                       , (all_errors)?", ":""
+                       , ctx->load_errors[LOAD_ERRORS_PAGE_ZERO_ENTRIES].counter
+                       , (now - ctx->load_errors[LOAD_ERRORS_PAGE_ZERO_ENTRIES].latest_end_time_ut) / USEC_PER_SEC
+        );
+        all_errors += ctx->load_errors[LOAD_ERRORS_PAGE_ZERO_ENTRIES].counter;
+    }
+
+    if(ctx->load_errors[LOAD_ERRORS_PAGE_UPDATE_ZERO].counter) {
+        buffer_sprintf(wb, "%s%zu pages had update every == 0 with entries > 1 (latest: %llu secs ago)"
+                       , (all_errors)?", ":""
+                       , ctx->load_errors[LOAD_ERRORS_PAGE_UPDATE_ZERO].counter
+                       , (now - ctx->load_errors[LOAD_ERRORS_PAGE_UPDATE_ZERO].latest_end_time_ut) / USEC_PER_SEC
+        );
+        all_errors += ctx->load_errors[LOAD_ERRORS_PAGE_UPDATE_ZERO].counter;
+    }
+
+    if(ctx->load_errors[LOAD_ERRORS_PAGE_FLEXY_TIME].counter) {
+        buffer_sprintf(wb, "%s%zu pages had a different number of points compared to their timestamps (latest: %llu secs ago; these page have been loaded)"
+                       , (all_errors)?", ":""
+                       , ctx->load_errors[LOAD_ERRORS_PAGE_FLEXY_TIME].counter
+                       , (now - ctx->load_errors[LOAD_ERRORS_PAGE_FLEXY_TIME].latest_end_time_ut) / USEC_PER_SEC
+        );
+        all_errors += ctx->load_errors[LOAD_ERRORS_PAGE_FLEXY_TIME].counter;
+    }
+
+    if(ctx->load_errors[LOAD_ERRORS_DROPPED_EXTENT].counter) {
+        buffer_sprintf(wb, "%s%zu extents have been dropped because they didn't have any valid pages"
+                       , (all_errors)?", ":""
+                       , ctx->load_errors[LOAD_ERRORS_DROPPED_EXTENT].counter
+        );
+        all_errors += ctx->load_errors[LOAD_ERRORS_DROPPED_EXTENT].counter;
+    }
+
+    if(all_errors)
+        info("DBENGINE: tier %d: %s", ctx->tier, buffer_tostring(wb));
+
+    buffer_free(wb);
+    return ret;
 }
 
 void finalize_rrd_files(struct rrdengine_instance *ctx)
@@ -1139,10 +1243,6 @@ void timer_cb(uv_timer_t* handle)
 
     uv_stop(handle->loop);
     uv_update_time(handle->loop);
-    if (unlikely(!ctx->metalog_ctx->initialized)) {
-        worker_is_idle();
-        return; /* Wait for the metadata log to initialize */
-    }
     rrdeng_test_quota(wc);
     debug(D_RRDENGINE, "%s: timeout reached.", __func__);
     if (likely(!wc->now_deleting_files && !wc->now_invalidating_dirty_pages)) {
@@ -1329,7 +1429,7 @@ void rrdeng_worker(void* arg)
     }
 
     /* cleanup operations of the event loop */
-    info("Shutting down RRD engine event loop.");
+    info("Shutting down RRD engine event loop for tier %d", ctx->tier);
 
     /*
      * uv_async_send after uv_close does not seem to crash in linux at the moment,
@@ -1344,7 +1444,7 @@ void rrdeng_worker(void* arg)
     wal_flush_transaction_buffer(wc);
     uv_run(loop, UV_RUN_DEFAULT);
 
-    info("Shutting down RRD engine event loop complete.");
+    info("Shutting down RRD engine event loop for tier %d complete", ctx->tier);
     /* TODO: don't let the API block by waiting to enqueue commands */
     uv_cond_destroy(&wc->cmd_cond);
 /*  uv_mutex_destroy(&wc->cmd_mutex); */
diff --git a/database/engine/rrdengine.h b/database/engine/rrdengine.h
index 4b383b622..fedadbe86 100644
--- a/database/engine/rrdengine.h
+++ b/database/engine/rrdengine.h
@@ -17,7 +17,6 @@
 #include "rrdenginelib.h"
 #include "datafile.h"
 #include "journalfile.h"
-#include "metadata_log/metadatalog.h"
 #include "rrdengineapi.h"
 #include "pagecache.h"
 #include "rrdenglocking.h"
@@ -37,29 +36,25 @@ struct rrdengine_instance;
 #define RRDENG_FILE_NUMBER_PRINT_TMPL "%1.1u-%10.10u"
 
 struct rrdeng_collect_handle {
-    struct rrdeng_metric_handle *metric_handle;
+    struct pg_cache_page_index *page_index;
     struct rrdeng_page_descr *descr;
     unsigned long page_correlation_id;
-    struct rrdengine_instance *ctx;
     // set to 1 when this dimension is not page aligned with the other dimensions in the chart
     uint8_t unaligned_page;
 };
 
 struct rrdeng_query_handle {
-    struct rrdeng_metric_handle *metric_handle;
     struct rrdeng_page_descr *descr;
     struct rrdengine_instance *ctx;
     struct pg_cache_page_index *page_index;
-    time_t next_page_time;
-    time_t now;
+    time_t wanted_start_time_s;
+    time_t now_s;
     unsigned position;
     unsigned entries;
-    TIER_QUERY_FETCH tier_query_fetch_type;
     storage_number *page;
-    usec_t page_end_time;
+    usec_t page_end_time_ut;
     uint32_t page_length;
-    usec_t dt;
-    time_t dt_sec;
+    time_t dt_s;
 };
 
 typedef enum {
@@ -110,8 +105,12 @@ struct rrdeng_cmdqueue {
 
 struct extent_io_descriptor {
     uv_fs_t req;
+    uv_work_t req_worker;
     uv_buf_t iov;
+    uv_file file;
     void *buf;
+    void *map_base;
+    size_t map_length;
     uint64_t pos;
     unsigned bytes;
     struct completion *completion;
@@ -230,8 +229,16 @@ extern rrdeng_stats_t global_flushing_pressure_page_deletions; /* number of dele
 #define SET_QUIESCE (1) /* set it before shutting down the instance, quiesce long running operations */
 #define QUIESCED    (2) /* is set after all threads have finished running */
 
+typedef enum {
+    LOAD_ERRORS_PAGE_FLIPPED_TIME = 0,
+    LOAD_ERRORS_PAGE_EQUAL_TIME = 1,
+    LOAD_ERRORS_PAGE_ZERO_ENTRIES = 2,
+    LOAD_ERRORS_PAGE_UPDATE_ZERO = 3,
+    LOAD_ERRORS_PAGE_FLEXY_TIME = 4,
+    LOAD_ERRORS_DROPPED_EXTENT = 5,
+} INVALID_PAGE_ID;
+
 struct rrdengine_instance {
-    struct metalog_instance *metalog_ctx;
     struct rrdengine_worker_config worker_config;
     struct completion rrdengine_completion;
     struct page_cache pg_cache;
@@ -254,16 +261,21 @@ struct rrdengine_instance {
     uint8_t page_type; /* Default page type for this context */
 
     struct rrdengine_statistics stats;
+
+    struct {
+        size_t counter;
+        usec_t latest_end_time_ut;
+    } load_errors[6];
 };
 
-extern void *dbengine_page_alloc(void);
-extern void dbengine_page_free(void *page);
+void *dbengine_page_alloc(void);
+void dbengine_page_free(void *page);
 
-extern int init_rrd_files(struct rrdengine_instance *ctx);
-extern void finalize_rrd_files(struct rrdengine_instance *ctx);
-extern void rrdeng_test_quota(struct rrdengine_worker_config* wc);
-extern void rrdeng_worker(void* arg);
-extern void rrdeng_enq_cmd(struct rrdengine_worker_config* wc, struct rrdeng_cmd *cmd);
-extern struct rrdeng_cmd rrdeng_deq_cmd(struct rrdengine_worker_config* wc);
+int init_rrd_files(struct rrdengine_instance *ctx);
+void finalize_rrd_files(struct rrdengine_instance *ctx);
+void rrdeng_test_quota(struct rrdengine_worker_config* wc);
+void rrdeng_worker(void* arg);
+void rrdeng_enq_cmd(struct rrdengine_worker_config* wc, struct rrdeng_cmd *cmd);
+struct rrdeng_cmd rrdeng_deq_cmd(struct rrdengine_worker_config* wc);
 
 #endif /* NETDATA_RRDENGINE_H */
diff --git a/database/engine/rrdengineapi.c b/database/engine/rrdengineapi.c
index f4da29407..27503baee 100755
--- a/database/engine/rrdengineapi.c
+++ b/database/engine/rrdengineapi.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 #include "rrdengine.h"
+#include "../storage_engine.h"
 
 /* Default global database instance */
 struct rrdengine_instance multidb_ctx_storage_tier0;
@@ -35,14 +36,31 @@ int default_multidb_disk_quota_mb = 256;
 /* Default behaviour is to unblock data collection if the page cache is full of dirty pages by dropping metrics */
 uint8_t rrdeng_drop_metrics_under_page_cache_pressure = 1;
 
-static inline struct rrdengine_instance *get_rrdeng_ctx_from_host(RRDHOST *host, int tier) {
-    if(tier < 0 || tier >= RRD_STORAGE_TIERS) tier = 0;
-    if(!host->storage_instance[tier]) tier = 0;
-    return (struct rrdengine_instance *)host->storage_instance[tier];
+// ----------------------------------------------------------------------------
+// metrics groups
+
+STORAGE_METRICS_GROUP *rrdeng_metrics_group_get(STORAGE_INSTANCE *db_instance __maybe_unused, uuid_t *uuid __maybe_unused) {
+    return callocz(1, sizeof(struct pg_alignment));
+}
+
+void rrdeng_metrics_group_release(STORAGE_INSTANCE *db_instance, STORAGE_METRICS_GROUP *smg) {
+    if(!smg) return;
+
+    struct rrdengine_instance *ctx = (struct rrdengine_instance *)db_instance;
+    struct pg_alignment *pa = (struct pg_alignment *)smg;
+    struct page_cache *pg_cache = &ctx->pg_cache;
+
+    uv_rwlock_rdlock(&pg_cache->metrics_index.lock);
+    if(pa->refcount == 0)
+        freez(pa);
+    uv_rwlock_rdunlock(&pg_cache->metrics_index.lock);
 }
 
+// ----------------------------------------------------------------------------
+// metric handle for legacy dbs
+
 /* This UUID is not unique across hosts */
-void rrdeng_generate_legacy_uuid(const char *dim_id, char *chart_id, uuid_t *ret_uuid)
+void rrdeng_generate_legacy_uuid(const char *dim_id, const char *chart_id, uuid_t *ret_uuid)
 {
     EVP_MD_CTX *evpctx;
     unsigned char hash_value[EVP_MAX_MD_SIZE];
@@ -75,98 +93,136 @@ void rrdeng_convert_legacy_uuid_to_multihost(char machine_guid[GUID_LEN + 1], uu
     memcpy(ret_uuid, hash_value, sizeof(uuid_t));
 }
 
-struct rrdeng_metric_handle {
-    RRDDIM *rd;
-    struct rrdengine_instance *ctx;
-    uuid_t *rrdeng_uuid;                            // database engine metric UUID
-    struct pg_cache_page_index *page_index;
-};
+STORAGE_METRIC_HANDLE *rrdeng_metric_get_legacy(STORAGE_INSTANCE *db_instance, const char *rd_id, const char *st_id, STORAGE_METRICS_GROUP *smg) {
+    uuid_t legacy_uuid;
+    rrdeng_generate_legacy_uuid(rd_id, st_id, &legacy_uuid);
+    return rrdeng_metric_get(db_instance, &legacy_uuid, smg);
+}
 
-void rrdeng_metric_free(STORAGE_METRIC_HANDLE *db_metric_handle) {
-    freez(db_metric_handle);
+// ----------------------------------------------------------------------------
+// metric handle
+
+void rrdeng_metric_release(STORAGE_METRIC_HANDLE *db_metric_handle) {
+    struct pg_cache_page_index *page_index = (struct pg_cache_page_index *)db_metric_handle;
+
+    unsigned short refcount = __atomic_sub_fetch(&page_index->refcount, 1, __ATOMIC_SEQ_CST);
+    if(refcount == 0 && page_index->alignment) {
+        __atomic_sub_fetch(&page_index->alignment->refcount, 1, __ATOMIC_SEQ_CST);
+        page_index->alignment = NULL;
+    }
 }
 
-STORAGE_METRIC_HANDLE *rrdeng_metric_init(RRDDIM *rd, STORAGE_INSTANCE *db_instance) {
+STORAGE_METRIC_HANDLE *rrdeng_metric_dup(STORAGE_METRIC_HANDLE *db_metric_handle) {
+    struct pg_cache_page_index *page_index = (struct pg_cache_page_index *)db_metric_handle;
+    __atomic_add_fetch(&page_index->refcount, 1, __ATOMIC_SEQ_CST);
+    return db_metric_handle;
+}
+
+STORAGE_METRIC_HANDLE *rrdeng_metric_get(STORAGE_INSTANCE *db_instance, uuid_t *uuid, STORAGE_METRICS_GROUP *smg) {
     struct rrdengine_instance *ctx = (struct rrdengine_instance *)db_instance;
-    struct page_cache *pg_cache;
-    uuid_t legacy_uuid;
-    uuid_t multihost_legacy_uuid;
-    Pvoid_t *PValue;
+    struct pg_alignment *pa = (struct pg_alignment *)smg;
+    struct page_cache *pg_cache = &ctx->pg_cache;
     struct pg_cache_page_index *page_index = NULL;
-    int is_multihost_child = 0;
-    RRDHOST *host = rd->rrdset->rrdhost;
-
-    pg_cache = &ctx->pg_cache;
-
-    rrdeng_generate_legacy_uuid(rd->id, rd->rrdset->id, &legacy_uuid);
-    if (host != localhost && is_storage_engine_shared((STORAGE_INSTANCE *)ctx))
-        is_multihost_child = 1;
 
     uv_rwlock_rdlock(&pg_cache->metrics_index.lock);
-    PValue = JudyHSGet(pg_cache->metrics_index.JudyHS_array, &legacy_uuid, sizeof(uuid_t));
-    if (likely(NULL != PValue)) {
+    Pvoid_t *PValue = JudyHSGet(pg_cache->metrics_index.JudyHS_array, uuid, sizeof(uuid_t));
+    if (likely(NULL != PValue))
         page_index = *PValue;
-    }
     uv_rwlock_rdunlock(&pg_cache->metrics_index.lock);
-    if (is_multihost_child || NULL == PValue) {
-        /* First time we see the legacy UUID or metric belongs to child host in multi-host DB.
-         * Drop legacy support, normal path */
-
-        uv_rwlock_rdlock(&pg_cache->metrics_index.lock);
-        PValue = JudyHSGet(pg_cache->metrics_index.JudyHS_array, &rd->metric_uuid, sizeof(uuid_t));
-        if (likely(NULL != PValue)) {
-            page_index = *PValue;
-        }
-        uv_rwlock_rdunlock(&pg_cache->metrics_index.lock);
-        if (NULL == PValue) {
-            uv_rwlock_wrlock(&pg_cache->metrics_index.lock);
-            PValue = JudyHSIns(&pg_cache->metrics_index.JudyHS_array, &rd->metric_uuid, sizeof(uuid_t), PJE0);
-            fatal_assert(NULL == *PValue); /* TODO: figure out concurrency model */
-            *PValue = page_index = create_page_index(&rd->metric_uuid);
-            page_index->prev = pg_cache->metrics_index.last_page_index;
-            pg_cache->metrics_index.last_page_index = page_index;
-            uv_rwlock_wrunlock(&pg_cache->metrics_index.lock);
+
+    if (likely(page_index)) {
+        __atomic_add_fetch(&page_index->refcount, 1, __ATOMIC_SEQ_CST);
+
+        if(pa) {
+            if(page_index->alignment && page_index->alignment != pa && page_index->writers > 0)
+                fatal("DBENGINE: page_index has a different alignment (page_index refcount is %u, writers is %u).",
+                        page_index->refcount, page_index->writers);
+
+            page_index->alignment = pa;
+            __atomic_add_fetch(&pa->refcount, 1, __ATOMIC_SEQ_CST);
         }
-    } else {
-        /* There are legacy UUIDs in the database, implement backward compatibility */
+    }
 
-        rrdeng_convert_legacy_uuid_to_multihost(rd->rrdset->rrdhost->machine_guid, &legacy_uuid,
-                                                &multihost_legacy_uuid);
+    return (STORAGE_METRIC_HANDLE *)page_index;
+}
+
+STORAGE_METRIC_HANDLE *rrdeng_metric_create(STORAGE_INSTANCE *db_instance, uuid_t *uuid, STORAGE_METRICS_GROUP *smg) {
+    internal_fatal(!db_instance, "DBENGINE: db_instance is NULL");
 
-        int need_to_store = uuid_compare(rd->metric_uuid, multihost_legacy_uuid);
+    struct rrdengine_instance *ctx = (struct rrdengine_instance *)db_instance;
+    struct pg_alignment *pa = (struct pg_alignment *)smg;
+    struct pg_cache_page_index *page_index;
+    struct page_cache *pg_cache = &ctx->pg_cache;
 
-        uuid_copy(rd->metric_uuid, multihost_legacy_uuid);
+    uv_rwlock_wrlock(&pg_cache->metrics_index.lock);
+    Pvoid_t *PValue = JudyHSIns(&pg_cache->metrics_index.JudyHS_array, uuid, sizeof(uuid_t), PJE0);
+    fatal_assert(NULL == *PValue); /* TODO: figure out concurrency model */
+    *PValue = page_index = create_page_index(uuid, ctx);
+    page_index->prev = pg_cache->metrics_index.last_page_index;
+    pg_cache->metrics_index.last_page_index = page_index;
+    page_index->alignment = pa;
+    page_index->refcount = 1;
+    if(pa)
+        pa->refcount++;
+    uv_rwlock_wrunlock(&pg_cache->metrics_index.lock);
+
+    return (STORAGE_METRIC_HANDLE *)page_index;
+}
+
+STORAGE_METRIC_HANDLE *rrdeng_metric_get_or_create(RRDDIM *rd, STORAGE_INSTANCE *db_instance, STORAGE_METRICS_GROUP *smg) {
+    STORAGE_METRIC_HANDLE *db_metric_handle;
+
+    db_metric_handle = rrdeng_metric_get(db_instance, &rd->metric_uuid, smg);
+    if(!db_metric_handle) {
+        db_metric_handle = rrdeng_metric_get_legacy(db_instance, rrddim_id(rd), rrdset_id(rd->rrdset), smg);
+        if(db_metric_handle) {
+            struct pg_cache_page_index *page_index = (struct pg_cache_page_index *)db_metric_handle;
+            uuid_copy(rd->metric_uuid, page_index->id);
+        }
+    }
+    if(!db_metric_handle)
+        db_metric_handle = rrdeng_metric_create(db_instance, &rd->metric_uuid, smg);
 
-        if (unlikely(need_to_store && !ctx->tier))
-            (void)sql_store_dimension(&rd->metric_uuid, rd->rrdset->chart_uuid, rd->id, rd->name, rd->multiplier, rd->divisor,
-                rd->algorithm);
+#ifdef NETDATA_INTERNAL_CHECKS
+    struct pg_cache_page_index *page_index = (struct pg_cache_page_index *)db_metric_handle;
+    if(uuid_compare(rd->metric_uuid, page_index->id) != 0) {
+        char uuid1[UUID_STR_LEN + 1];
+        char uuid2[UUID_STR_LEN + 1];
+
+        uuid_unparse(rd->metric_uuid, uuid1);
+        uuid_unparse(page_index->id, uuid2);
+        fatal("DBENGINE: uuids do not match, asked for metric '%s', but got page_index of metric '%s'", uuid1, uuid2);
     }
 
-    struct rrdeng_metric_handle *mh = mallocz(sizeof(struct rrdeng_metric_handle));
-    mh->rd = rd;
-    mh->ctx = ctx;
-    mh->rrdeng_uuid = &page_index->id;
-    mh->page_index = page_index;
-    return (STORAGE_METRIC_HANDLE *)mh;
+    struct rrdengine_instance *ctx = (struct rrdengine_instance *)db_instance;
+    if(page_index->ctx != ctx)
+        fatal("DBENGINE: mixed up rrdengine instances, asked for metric from %p, got from %p", ctx, page_index->ctx);
+#endif
+
+    return db_metric_handle;
 }
 
+
+// ----------------------------------------------------------------------------
+// collect ops
+
 /*
  * Gets a handle for storing metrics to the database.
  * The handle must be released with rrdeng_store_metric_final().
  */
-STORAGE_COLLECT_HANDLE *rrdeng_store_metric_init(STORAGE_METRIC_HANDLE *db_metric_handle) {
-    struct rrdeng_metric_handle *metric_handle = (struct rrdeng_metric_handle *)db_metric_handle;
-
+STORAGE_COLLECT_HANDLE *rrdeng_store_metric_init(STORAGE_METRIC_HANDLE *db_metric_handle, uint32_t update_every) {
+    struct pg_cache_page_index *page_index = (struct pg_cache_page_index *)db_metric_handle;
     struct rrdeng_collect_handle *handle;
-    struct pg_cache_page_index *page_index;
+
+    if(!page_index->alignment)
+        fatal("DBENGINE: metric group is required for collect operations");
 
     handle = callocz(1, sizeof(struct rrdeng_collect_handle));
-    handle->metric_handle = metric_handle;
-    handle->ctx = metric_handle->ctx;
+    handle->page_index = page_index;
     handle->descr = NULL;
     handle->unaligned_page = 0;
+    page_index->latest_update_every_s = update_every;
 
-    page_index = metric_handle->page_index;
     uv_rwlock_wrlock(&page_index->lock);
     ++page_index->writers;
     uv_rwlock_wrunlock(&page_index->lock);
@@ -214,7 +270,7 @@ static int page_has_only_empty_metrics(struct rrdeng_page_descr *descr)
 void rrdeng_store_metric_flush_current_page(STORAGE_COLLECT_HANDLE *collection_handle) {
     struct rrdeng_collect_handle *handle = (struct rrdeng_collect_handle *)collection_handle;
     // struct rrdeng_metric_handle *metric_handle = (struct rrdeng_metric_handle *)handle->metric_handle;
-    struct rrdengine_instance *ctx = handle->ctx;
+    struct rrdengine_instance *ctx = handle->page_index->ctx;
     struct rrdeng_page_descr *descr = handle->descr;
 
     if (unlikely(!ctx)) return;
@@ -227,9 +283,7 @@ void rrdeng_store_metric_flush_current_page(STORAGE_COLLECT_HANDLE *collection_h
 
         page_is_empty = page_has_only_empty_metrics(descr);
         if (page_is_empty) {
-            debug(D_RRDENGINE, "Page has empty metrics only, deleting:");
-            if (unlikely(debug_flags & D_RRDENGINE))
-                print_page_cache_descr(descr);
+            print_page_cache_descr(descr, "Page has empty metrics only, deleting", true);
             pg_cache_put(ctx, descr);
             pg_cache_punch_hole(ctx, descr, 1, 0, NULL);
         } else
@@ -242,8 +296,8 @@ void rrdeng_store_metric_flush_current_page(STORAGE_COLLECT_HANDLE *collection_h
     handle->descr = NULL;
 }
 
-void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle,
-                              usec_t point_in_time,
+static void rrdeng_store_metric_next_internal(STORAGE_COLLECT_HANDLE *collection_handle,
+                              usec_t point_in_time_ut,
                               NETDATA_DOUBLE n,
                               NETDATA_DOUBLE min_value,
                               NETDATA_DOUBLE max_value,
@@ -252,11 +306,10 @@ void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle,
                               SN_FLAGS flags)
 {
     struct rrdeng_collect_handle *handle = (struct rrdeng_collect_handle *)collection_handle;
-    struct rrdeng_metric_handle *metric_handle = (struct rrdeng_metric_handle *)handle->metric_handle;
-    struct rrdengine_instance *ctx = handle->ctx;
+    struct pg_cache_page_index *page_index = handle->page_index;
+    struct rrdengine_instance *ctx = handle->page_index->ctx;
     struct page_cache *pg_cache = &ctx->pg_cache;
     struct rrdeng_page_descr *descr = handle->descr;
-    RRDDIM *rd = metric_handle->rd;
 
     void *page;
     uint8_t must_flush_unaligned_page = 0, perfect_page_alignment = 0;
@@ -264,21 +317,33 @@ void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle,
     if (descr) {
         /* Make alignment decisions */
 
-        if (descr->page_length == rd->rrdset->rrddim_page_alignment) {
+#ifdef NETDATA_INTERNAL_CHECKS
+        if(descr->end_time_ut + page_index->latest_update_every_s * USEC_PER_SEC != point_in_time_ut) {
+            char buffer[200 + 1];
+            snprintfz(buffer, 200,
+                      "metrics collected are %s, end_time_ut = %llu, point_in_time_ut = %llu, update_every = %u, delta = %llu",
+                      (point_in_time_ut / USEC_PER_SEC - descr->end_time_ut / USEC_PER_SEC > page_index->latest_update_every_s)?"far apart":"not aligned",
+                      descr->end_time_ut / USEC_PER_SEC,
+                      point_in_time_ut / USEC_PER_SEC,
+                      page_index->latest_update_every_s,
+                      point_in_time_ut / USEC_PER_SEC - descr->end_time_ut / USEC_PER_SEC);
+            print_page_cache_descr(descr, buffer, false);
+        }
+#endif
+
+        if (descr->page_length == page_index->alignment->page_length) {
             /* this is the leading dimension that defines chart alignment */
             perfect_page_alignment = 1;
         }
         /* is the metric far enough out of alignment with the others? */
-        if (unlikely(descr->page_length + PAGE_POINT_SIZE_BYTES(descr) < rd->rrdset->rrddim_page_alignment)) {
+        if (unlikely(descr->page_length + PAGE_POINT_SIZE_BYTES(descr) < page_index->alignment->page_length)) {
             handle->unaligned_page = 1;
-            debug(D_RRDENGINE, "Metric page is not aligned with chart:");
-            if (unlikely(debug_flags & D_RRDENGINE))
-                print_page_cache_descr(descr);
+            print_page_cache_descr(descr, "Metric page is not aligned with chart", true);
         }
         if (unlikely(handle->unaligned_page &&
                      /* did the other metrics change page? */
-                     rd->rrdset->rrddim_page_alignment <= PAGE_POINT_SIZE_BYTES(descr))) {
-            debug(D_RRDENGINE, "Flushing unaligned metric page.");
+                     page_index->alignment->page_length <= PAGE_POINT_SIZE_BYTES(descr))) {
+            print_page_cache_descr(descr, "must_flush_unaligned_page = 1", true);
             must_flush_unaligned_page = 1;
             handle->unaligned_page = 0;
         }
@@ -286,16 +351,21 @@ void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle,
     if (unlikely(NULL == descr ||
                  descr->page_length + PAGE_POINT_SIZE_BYTES(descr) > RRDENG_BLOCK_SIZE ||
                  must_flush_unaligned_page)) {
-        rrdeng_store_metric_flush_current_page(collection_handle);
 
-        page = rrdeng_create_page(ctx, &metric_handle->page_index->id, &descr);
+        if(descr) {
+            print_page_cache_descr(descr, "flushing metric", true);
+            rrdeng_store_metric_flush_current_page(collection_handle);
+        }
+
+        page = rrdeng_create_page(ctx, &page_index->id, &descr);
         fatal_assert(page);
 
+        descr->update_every_s = page_index->latest_update_every_s;
         handle->descr = descr;
 
         handle->page_correlation_id = rrd_atomic_fetch_add(&pg_cache->committed_page_index.latest_corr_id, 1);
 
-        if (0 == rd->rrdset->rrddim_page_alignment) {
+        if (0 == page_index->alignment->page_length) {
             /* this is the leading dimension that defines chart alignment */
             perfect_page_alignment = 1;
         }
@@ -330,13 +400,13 @@ void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle,
         break;
     }
 
-    pg_cache_atomic_set_pg_info(descr, point_in_time, descr->page_length + PAGE_POINT_SIZE_BYTES(descr));
+    pg_cache_atomic_set_pg_info(descr, point_in_time_ut, descr->page_length + PAGE_POINT_SIZE_BYTES(descr));
 
     if (perfect_page_alignment)
-        rd->rrdset->rrddim_page_alignment = descr->page_length;
-    if (unlikely(INVALID_TIME == descr->start_time)) {
+        page_index->alignment->page_length = descr->page_length;
+    if (unlikely(INVALID_TIME == descr->start_time_ut)) {
         unsigned long new_metric_API_producers, old_metric_API_max_producers, ret_metric_API_max_producers;
-        descr->start_time = point_in_time;
+        descr->start_time_ut = point_in_time_ut;
 
         new_metric_API_producers = rrd_atomic_add_fetch(&ctx->stats.metric_API_producers, 1);
         while (unlikely(new_metric_API_producers > (old_metric_API_max_producers = ctx->metric_API_max_producers))) {
@@ -350,20 +420,111 @@ void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle,
             }
         }
 
-        pg_cache_insert(ctx, metric_handle->page_index, descr);
+        pg_cache_insert(ctx, page_index, descr);
     } else {
-        pg_cache_add_new_metric_time(metric_handle->page_index, descr);
+        pg_cache_add_new_metric_time(page_index, descr);
     }
+
+//    {
+//        unsigned char u[16] = { 0x0C, 0x0A, 0x40, 0xD6, 0x2A, 0x43, 0x4A, 0x7C, 0x95, 0xF7, 0xD1, 0x1E, 0x0C, 0x9E, 0x8A, 0xE7 };
+//        if(uuid_compare(u, page_index->id) == 0) {
+//            char buffer[100];
+//            snprintfz(buffer, 100, "store system.cpu, collect:%u, page_index first:%u, last:%u",
+//                      (uint32_t)(point_in_time / USEC_PER_SEC),
+//                      (uint32_t)(page_index->oldest_time / USEC_PER_SEC),
+//                      (uint32_t)(page_index->latest_time / USEC_PER_SEC));
+//
+//            print_page_cache_descr(descr, buffer, false);
+//        }
+//    }
 }
 
+void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle,
+                              usec_t point_in_time_ut,
+                              NETDATA_DOUBLE n,
+                              NETDATA_DOUBLE min_value,
+                              NETDATA_DOUBLE max_value,
+                              uint16_t count,
+                              uint16_t anomaly_count,
+                              SN_FLAGS flags)
+{
+    struct rrdeng_collect_handle *handle = (struct rrdeng_collect_handle *)collection_handle;
+    struct pg_cache_page_index *page_index = handle->page_index;
+    struct rrdeng_page_descr *descr = handle->descr;
+
+    if(likely(descr)) {
+        usec_t last_point_in_time_ut = descr->end_time_ut;
+        usec_t update_every_ut = page_index->latest_update_every_s * USEC_PER_SEC;
+        size_t points_gap = (point_in_time_ut <= last_point_in_time_ut) ?
+                                (size_t)0 :
+                                (size_t)((point_in_time_ut - last_point_in_time_ut) / update_every_ut);
+
+        if(unlikely(points_gap != 1)) {
+            if (unlikely(points_gap <= 0)) {
+                time_t now = now_realtime_sec();
+                static __thread size_t counter = 0;
+                static __thread time_t last_time_logged = 0;
+                counter++;
+
+                if(now - last_time_logged > 600) {
+                    error("DBENGINE: collected point is in the past (repeated %zu times in the last %zu secs). Ignoring these data collection points.",
+                          counter, (size_t)(last_time_logged?(now - last_time_logged):0));
+
+                    last_time_logged = now;
+                    counter = 0;
+                }
+                return;
+            }
+
+            size_t point_size = PAGE_POINT_SIZE_BYTES(descr);
+            size_t page_size_in_points = RRDENG_BLOCK_SIZE / point_size;
+            size_t used_points = descr->page_length / point_size;
+            size_t remaining_points_in_page = page_size_in_points - used_points;
+
+            bool new_point_is_aligned = true;
+            if(unlikely((point_in_time_ut - last_point_in_time_ut) / points_gap != update_every_ut))
+                new_point_is_aligned = false;
+
+            if(unlikely(points_gap > remaining_points_in_page || !new_point_is_aligned)) {
+//                char buffer[200];
+//                snprintfz(buffer, 200, "data collection skipped %zu points, last stored point %llu, new point %llu, update every %d. Cutting page.",
+//                      points_gap, last_point_in_time_ut / USEC_PER_SEC, point_in_time_ut / USEC_PER_SEC, page_index->latest_update_every_s);
+//                print_page_cache_descr(descr, buffer, false);
+
+                rrdeng_store_metric_flush_current_page(collection_handle);
+            }
+            else {
+//                char buffer[200];
+//                snprintfz(buffer, 200, "data collection skipped %zu points, last stored point %llu, new point %llu, update every %d. Filling the gap.",
+//                      points_gap, last_point_in_time_ut / USEC_PER_SEC, point_in_time_ut / USEC_PER_SEC, page_index->latest_update_every_s);
+//                print_page_cache_descr(descr, buffer, false);
+
+                // loop to fill the gap
+                usec_t step_ut = page_index->latest_update_every_s * USEC_PER_SEC;
+                usec_t last_point_filled_ut = last_point_in_time_ut + step_ut;
+
+                while (last_point_filled_ut < point_in_time_ut) {
+                    rrdeng_store_metric_next_internal(
+                        collection_handle, last_point_filled_ut, NAN, NAN, NAN,
+                        1, 0, SN_EMPTY_SLOT);
+
+                    last_point_filled_ut += step_ut;
+                }
+            }
+        }
+    }
+
+    rrdeng_store_metric_next_internal(collection_handle, point_in_time_ut, n, min_value, max_value, count, anomaly_count, flags);
+}
+
+
 /*
  * Releases the database reference from the handle for storing metrics.
  * Returns 1 if it's safe to delete the dimension.
  */
 int rrdeng_store_metric_finalize(STORAGE_COLLECT_HANDLE *collection_handle) {
     struct rrdeng_collect_handle *handle = (struct rrdeng_collect_handle *)collection_handle;
-    struct rrdeng_metric_handle *metric_handle = (struct rrdeng_metric_handle *)handle->metric_handle;
-    struct pg_cache_page_index *page_index = metric_handle->page_index;
+    struct pg_cache_page_index *page_index = handle->page_index;
 
     uint8_t can_delete_metric = 0;
 
@@ -378,6 +539,18 @@ int rrdeng_store_metric_finalize(STORAGE_COLLECT_HANDLE *collection_handle) {
     return can_delete_metric;
 }
 
+void rrdeng_store_metric_change_collection_frequency(STORAGE_COLLECT_HANDLE *collection_handle, int update_every) {
+    struct rrdeng_collect_handle *handle = (struct rrdeng_collect_handle *)collection_handle;
+    struct pg_cache_page_index *page_index = handle->page_index;
+    rrdeng_store_metric_flush_current_page(collection_handle);
+    uv_rwlock_rdlock(&page_index->lock);
+    page_index->latest_update_every_s = update_every;
+    uv_rwlock_rdunlock(&page_index->lock);
+}
+
+// ----------------------------------------------------------------------------
+// query ops
+
 //static inline uint32_t *pginfo_to_dt(struct rrdeng_page_info *page_info)
 //{
 //    return (uint32_t *)&page_info->scratch[0];
@@ -392,49 +565,45 @@ int rrdeng_store_metric_finalize(STORAGE_COLLECT_HANDLE *collection_handle) {
  * Gets a handle for loading metrics from the database.
  * The handle must be released with rrdeng_load_metric_final().
  */
-void rrdeng_load_metric_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct rrddim_query_handle *rrdimm_handle, time_t start_time, time_t end_time, TIER_QUERY_FETCH tier_query_fetch_type)
+void rrdeng_load_metric_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct storage_engine_query_handle *rrdimm_handle, time_t start_time_s, time_t end_time_s)
 {
-    struct rrdeng_metric_handle *metric_handle = (struct rrdeng_metric_handle *)db_metric_handle;
-    struct rrdengine_instance *ctx = metric_handle->ctx;
-    RRDDIM *rd = metric_handle->rd;
+    struct pg_cache_page_index *page_index = (struct pg_cache_page_index *)db_metric_handle;
+    struct rrdengine_instance *ctx = page_index->ctx;
 
     // fprintf(stderr, "%s: %s/%s start time %ld, end time %ld\n", __FUNCTION__ , rd->rrdset->name, rd->name, start_time, end_time);
 
     struct rrdeng_query_handle *handle;
     unsigned pages_nr;
 
-    rrdimm_handle->start_time = start_time;
-    rrdimm_handle->end_time = end_time;
+    if(!page_index->latest_update_every_s)
+        page_index->latest_update_every_s = default_rrd_update_every;
+
+    rrdimm_handle->start_time_s = start_time_s;
+    rrdimm_handle->end_time_s = end_time_s;
 
     handle = callocz(1, sizeof(struct rrdeng_query_handle));
-    handle->next_page_time = start_time;
-    handle->now = start_time;
-    handle->tier_query_fetch_type = tier_query_fetch_type;
-    // TODO we should store the dt of each page in each page
-    // this will produce wrong values for dt in case the user changes
-    // the update every of the charts or the tier grouping iterations
-    handle->dt_sec = get_tier_grouping(ctx->tier) * (time_t)rd->update_every;
-    handle->dt = handle->dt_sec * USEC_PER_SEC;
+    handle->wanted_start_time_s = start_time_s;
+    handle->now_s = start_time_s;
     handle->position = 0;
     handle->ctx = ctx;
-    handle->metric_handle = metric_handle;
     handle->descr = NULL;
+    handle->dt_s = page_index->latest_update_every_s;
     rrdimm_handle->handle = (STORAGE_QUERY_HANDLE *)handle;
-    pages_nr = pg_cache_preload(ctx, metric_handle->rrdeng_uuid, start_time * USEC_PER_SEC, end_time * USEC_PER_SEC,
+    pages_nr = pg_cache_preload(ctx, &page_index->id, start_time_s * USEC_PER_SEC, end_time_s * USEC_PER_SEC,
                                 NULL, &handle->page_index);
     if (unlikely(NULL == handle->page_index || 0 == pages_nr))
         // there are no metrics to load
-        handle->next_page_time = INVALID_TIME;
+        handle->wanted_start_time_s = INVALID_TIME;
 }
 
-static int rrdeng_load_page_next(struct rrddim_query_handle *rrdimm_handle) {
+static int rrdeng_load_page_next(struct storage_engine_query_handle *rrdimm_handle, bool debug_this __maybe_unused) {
     struct rrdeng_query_handle *handle = (struct rrdeng_query_handle *)rrdimm_handle->handle;
 
     struct rrdengine_instance *ctx = handle->ctx;
     struct rrdeng_page_descr *descr = handle->descr;
 
     uint32_t page_length;
-    usec_t page_end_time;
+    usec_t page_end_time_ut;
     unsigned position;
 
     if (likely(descr)) {
@@ -446,14 +615,15 @@ static int rrdeng_load_page_next(struct rrddim_query_handle *rrdimm_handle) {
 
         pg_cache_put(ctx, descr);
         handle->descr = NULL;
-        handle->next_page_time = (handle->page_end_time / USEC_PER_SEC) + 1;
+        handle->wanted_start_time_s = (time_t)((handle->page_end_time_ut / USEC_PER_SEC) + handle->dt_s);
 
-        if (unlikely(handle->next_page_time > rrdimm_handle->end_time))
+        if (unlikely(handle->wanted_start_time_s > rrdimm_handle->end_time_s))
             return 1;
     }
 
-    usec_t next_page_time = handle->next_page_time * USEC_PER_SEC;
-    descr = pg_cache_lookup_next(ctx, handle->page_index, &handle->page_index->id, next_page_time, rrdimm_handle->end_time * USEC_PER_SEC);
+    usec_t wanted_start_time_ut = handle->wanted_start_time_s * USEC_PER_SEC;
+    descr = pg_cache_lookup_next(ctx, handle->page_index, &handle->page_index->id,
+        wanted_start_time_ut, rrdimm_handle->end_time_s * USEC_PER_SEC);
     if (NULL == descr)
         return 1;
 
@@ -462,77 +632,116 @@ static int rrdeng_load_page_next(struct rrddim_query_handle *rrdimm_handle) {
 #endif
 
     handle->descr = descr;
-    pg_cache_atomic_get_pg_info(descr, &page_end_time, &page_length);
-    if (unlikely(INVALID_TIME == descr->start_time || INVALID_TIME == page_end_time))
+    pg_cache_atomic_get_pg_info(descr, &page_end_time_ut, &page_length);
+    if (unlikely(INVALID_TIME == descr->start_time_ut || INVALID_TIME == page_end_time_ut || 0 == descr->update_every_s)) {
+        error("DBENGINE: discarding invalid page descriptor (start_time = %llu, end_time = %llu, update_every_s = %d)",
+              descr->start_time_ut, page_end_time_ut, descr->update_every_s);
         return 1;
+    }
 
-    if (unlikely(descr->start_time != page_end_time && next_page_time > descr->start_time)) {
+    if (unlikely(descr->start_time_ut != page_end_time_ut && wanted_start_time_ut > descr->start_time_ut)) {
         // we're in the middle of the page somewhere
         unsigned entries = page_length / PAGE_POINT_SIZE_BYTES(descr);
-        position = ((uint64_t)(next_page_time - descr->start_time)) * (entries - 1) /
-                   (page_end_time - descr->start_time);
+        position = ((uint64_t)(wanted_start_time_ut - descr->start_time_ut)) * (entries - 1) /
+                   (page_end_time_ut - descr->start_time_ut);
     }
     else
         position = 0;
 
-    handle->page_end_time = page_end_time;
+    handle->page_end_time_ut = page_end_time_ut;
     handle->page_length = page_length;
+    handle->entries = page_length / PAGE_POINT_SIZE_BYTES(descr);
     handle->page = descr->pg_cache_descr->page;
-    usec_t entries = handle->entries = page_length / PAGE_POINT_SIZE_BYTES(descr);
-    if (likely(entries > 1))
-        handle->dt = (page_end_time - descr->start_time) / (entries - 1);
-    else {
-        // TODO we should store the dt of each page in each page
-        // now we keep the dt of whatever was before
-        ;
-    }
-
-    handle->dt_sec = (time_t)(handle->dt / USEC_PER_SEC);
+    handle->dt_s = descr->update_every_s;
     handle->position = position;
 
+//    if(debug_this)
+//        info("DBENGINE: rrdeng_load_page_next(), "
+//             "position:%d, "
+//             "start_time_ut:%llu, "
+//             "page_end_time_ut:%llu, "
+//             "next_page_time_ut:%llu, "
+//             "in_out:%s"
+//             , position
+//             , descr->start_time_ut
+//             , page_end_time_ut
+//             ,
+//            wanted_start_time_ut, in_out?"true":"false"
+//             );
+
     return 0;
 }
 
 // Returns the metric and sets its timestamp into current_time
 // IT IS REQUIRED TO **ALWAYS** SET ALL RETURN VALUES (current_time, end_time, flags)
 // IT IS REQUIRED TO **ALWAYS** KEEP TRACK OF TIME, EVEN OUTSIDE THE DATABASE BOUNDARIES
-STORAGE_POINT rrdeng_load_metric_next(struct rrddim_query_handle *rrdimm_handle) {
-    struct rrdeng_query_handle *handle = (struct rrdeng_query_handle *)rrdimm_handle->handle;
+STORAGE_POINT rrdeng_load_metric_next(struct storage_engine_query_handle *rrddim_handle) {
+    struct rrdeng_query_handle *handle = (struct rrdeng_query_handle *)rrddim_handle->handle;
     // struct rrdeng_metric_handle *metric_handle = handle->metric_handle;
 
-    STORAGE_POINT sp;
     struct rrdeng_page_descr *descr = handle->descr;
+    time_t now = handle->now_s + handle->dt_s;
+
+//    bool debug_this = false;
+//    {
+//        unsigned char u[16] = { 0x0C, 0x0A, 0x40, 0xD6, 0x2A, 0x43, 0x4A, 0x7C, 0x95, 0xF7, 0xD1, 0x1E, 0x0C, 0x9E, 0x8A, 0xE7 };
+//        if(uuid_compare(u, handle->page_index->id) == 0) {
+//            char buffer[100];
+//            snprintfz(buffer, 100, "load system.cpu, now:%u, dt:%u, position:%u page_index first:%u, last:%u",
+//                      (uint32_t)(now),
+//                      (uint32_t)(handle->dt_s),
+//                      (uint32_t)(handle->position),
+//                      (uint32_t)(handle->page_index->oldest_time / USEC_PER_SEC),
+//                      (uint32_t)(handle->page_index->latest_time / USEC_PER_SEC));
+//
+//            print_page_cache_descr(descr, buffer, false);
+//            debug_this = true;
+//        }
+//    }
+
+    STORAGE_POINT sp;
     unsigned position = handle->position + 1;
-    time_t now = handle->now + handle->dt_sec;
     storage_number_tier1_t tier1_value;
 
-    if (unlikely(INVALID_TIME == handle->next_page_time)) {
-        handle->next_page_time = INVALID_TIME;
-        handle->now = now;
-        storage_point_empty(sp, now - handle->dt_sec, now);
+    if (unlikely(INVALID_TIME == handle->wanted_start_time_s)) {
+        handle->wanted_start_time_s = INVALID_TIME;
+        handle->now_s = now;
+        storage_point_empty(sp, now - handle->dt_s, now);
         return sp;
     }
 
     if (unlikely(!descr || position >= handle->entries)) {
         // We need to get a new page
-        if(rrdeng_load_page_next(rrdimm_handle)) {
+        if(rrdeng_load_page_next(rrddim_handle, false)) {
             // next calls will not load any more metrics
-            handle->next_page_time = INVALID_TIME;
-            handle->now = now;
-            storage_point_empty(sp, now - handle->dt_sec, now);
+            handle->wanted_start_time_s = INVALID_TIME;
+            handle->now_s = now;
+            storage_point_empty(sp, now - handle->dt_s, now);
             return sp;
         }
 
         descr = handle->descr;
         position = handle->position;
-        now = (time_t)((descr->start_time + position * handle->dt) / USEC_PER_SEC);
+        now = (time_t)((descr->start_time_ut / USEC_PER_SEC) + position * descr->update_every_s);
+
+//        if(debug_this) {
+//            char buffer[100];
+//            snprintfz(buffer, 100, "NEW PAGE system.cpu, now:%u, dt:%u, position:%u page_index first:%u, last:%u",
+//                      (uint32_t)(now),
+//                      (uint32_t)(handle->dt_s),
+//                      (uint32_t)(handle->position),
+//                      (uint32_t)(handle->page_index->oldest_time / USEC_PER_SEC),
+//                      (uint32_t)(handle->page_index->latest_time / USEC_PER_SEC));
+//
+//            print_page_cache_descr(descr, buffer, false);
+//        }
     }
 
-    sp.start_time = now - handle->dt_sec;
+    sp.start_time = now - handle->dt_s;
     sp.end_time = now;
 
     handle->position = position;
-    handle->now = now;
+    handle->now_s = now;
 
     switch(descr->type) {
         case PAGE_METRICS: {
@@ -567,24 +776,32 @@ STORAGE_POINT rrdeng_load_metric_next(struct rrddim_query_handle *rrdimm_handle)
         break;
     }
 
-    if (unlikely(now >= rrdimm_handle->end_time)) {
+    if (unlikely(now >= rrddim_handle->end_time_s)) {
         // next calls will not load any more metrics
-        handle->next_page_time = INVALID_TIME;
+        handle->wanted_start_time_s = INVALID_TIME;
     }
 
+//    if(debug_this)
+//        info("DBENGINE: returning point: "
+//             "time from %ld to %ld   //  query from %ld to %ld   //   wanted_start_time_s %ld"
+//             , sp.start_time, sp.end_time
+//             , rrddim_handle->start_time_s, rrddim_handle->end_time_s
+//             , handle->wanted_start_time_s
+//             );
+
     return sp;
 }
 
-int rrdeng_load_metric_is_finished(struct rrddim_query_handle *rrdimm_handle)
+int rrdeng_load_metric_is_finished(struct storage_engine_query_handle *rrdimm_handle)
 {
     struct rrdeng_query_handle *handle = (struct rrdeng_query_handle *)rrdimm_handle->handle;
-    return (INVALID_TIME == handle->next_page_time);
+    return (INVALID_TIME == handle->wanted_start_time_s);
 }
 
 /*
  * Releases the database reference from the handle for loading metrics.
  */
-void rrdeng_load_metric_finalize(struct rrddim_query_handle *rrdimm_handle)
+void rrdeng_load_metric_finalize(struct storage_engine_query_handle *rrdimm_handle)
 {
     struct rrdeng_query_handle *handle = (struct rrdeng_query_handle *)rrdimm_handle->handle;
     struct rrdengine_instance *ctx = handle->ctx;
@@ -603,46 +820,12 @@ void rrdeng_load_metric_finalize(struct rrddim_query_handle *rrdimm_handle)
 }
 
 time_t rrdeng_metric_latest_time(STORAGE_METRIC_HANDLE *db_metric_handle) {
-    struct rrdeng_metric_handle *metric_handle = (struct rrdeng_metric_handle *)db_metric_handle;
-
-    struct pg_cache_page_index *page_index = metric_handle->page_index;
-    return page_index->latest_time / USEC_PER_SEC;
+    struct pg_cache_page_index *page_index = (struct pg_cache_page_index *)db_metric_handle;
+    return (time_t)(page_index->latest_time_ut / USEC_PER_SEC);
 }
 time_t rrdeng_metric_oldest_time(STORAGE_METRIC_HANDLE *db_metric_handle) {
-    struct rrdeng_metric_handle *metric_handle = (struct rrdeng_metric_handle *)db_metric_handle;
-
-    struct pg_cache_page_index *page_index = metric_handle->page_index;
-    return page_index->oldest_time / USEC_PER_SEC;
-}
-
-int rrdeng_metric_latest_time_by_uuid(uuid_t *dim_uuid, time_t *first_entry_t, time_t *last_entry_t, int tier)
-{
-    struct page_cache *pg_cache;
-    struct rrdengine_instance *ctx;
-    Pvoid_t *PValue;
-    struct pg_cache_page_index *page_index = NULL;
-
-    ctx = get_rrdeng_ctx_from_host(localhost, tier);
-    if (unlikely(!ctx)) {
-        error("Failed to fetch multidb context");
-        return 1;
-    }
-    pg_cache = &ctx->pg_cache;
-
-    uv_rwlock_rdlock(&pg_cache->metrics_index.lock);
-    PValue = JudyHSGet(pg_cache->metrics_index.JudyHS_array, dim_uuid, sizeof(uuid_t));
-    if (likely(NULL != PValue)) {
-        page_index = *PValue;
-    }
-    uv_rwlock_rdunlock(&pg_cache->metrics_index.lock);
-
-    if (likely(page_index)) {
-        *first_entry_t = page_index->oldest_time / USEC_PER_SEC;
-        *last_entry_t = page_index->latest_time / USEC_PER_SEC;
-        return 0;
-    }
-
-    return 1;
+    struct pg_cache_page_index *page_index = (struct pg_cache_page_index *)db_metric_handle;
+    return (time_t)(page_index->oldest_time_ut / USEC_PER_SEC);
 }
 
 int rrdeng_metric_retention_by_uuid(STORAGE_INSTANCE *si, uuid_t *dim_uuid, time_t *first_entry_t, time_t *last_entry_t)
@@ -667,8 +850,8 @@ int rrdeng_metric_retention_by_uuid(STORAGE_INSTANCE *si, uuid_t *dim_uuid, time
     uv_rwlock_rdunlock(&pg_cache->metrics_index.lock);
 
     if (likely(page_index)) {
-        *first_entry_t = page_index->oldest_time / USEC_PER_SEC;
-        *last_entry_t = page_index->latest_time / USEC_PER_SEC;
+        *first_entry_t = page_index->oldest_time_ut / USEC_PER_SEC;
+        *last_entry_t = page_index->latest_time_ut / USEC_PER_SEC;
         return 0;
     }
 
@@ -695,7 +878,7 @@ void *rrdeng_create_page(struct rrdengine_instance *ctx, uuid_t *id, struct rrde
 
     debug(D_RRDENGINE, "Created new page:");
     if (unlikely(debug_flags & D_RRDENGINE))
-        print_page_cache_descr(descr);
+        print_page_cache_descr(descr, "", true);
     rrdeng_page_descr_mutex_unlock(ctx, descr);
     *ret_descr = descr;
     return page;
@@ -767,13 +950,13 @@ void *rrdeng_get_latest_page(struct rrdengine_instance *ctx, uuid_t *id, void **
 }
 
 /* Gets a reference for the page */
-void *rrdeng_get_page(struct rrdengine_instance *ctx, uuid_t *id, usec_t point_in_time, void **handle)
+void *rrdeng_get_page(struct rrdengine_instance *ctx, uuid_t *id, usec_t point_in_time_ut, void **handle)
 {
     struct rrdeng_page_descr *descr;
     struct page_cache_descr *pg_cache_descr;
 
     debug(D_RRDENGINE, "Reading existing page:");
-    descr = pg_cache_lookup(ctx, NULL, id, point_in_time);
+    descr = pg_cache_lookup(ctx, NULL, id, point_in_time_ut);
     if (NULL == descr) {
         *handle = NULL;
 
@@ -849,7 +1032,7 @@ void rrdeng_put_page(struct rrdengine_instance *ctx, void *handle)
  * Returns 0 on success, negative on error
  */
 int rrdeng_init(RRDHOST *host, struct rrdengine_instance **ctxp, char *dbfiles_path, unsigned page_cache_mb,
-                unsigned disk_space_mb, int tier) {
+                unsigned disk_space_mb, size_t tier) {
     struct rrdengine_instance *ctx;
     int error;
     uint32_t max_open_files;
@@ -897,7 +1080,6 @@ int rrdeng_init(RRDHOST *host, struct rrdengine_instance **ctxp, char *dbfiles_p
     ctx->drop_metrics_under_page_cache_pressure = rrdeng_drop_metrics_under_page_cache_pressure;
     ctx->metric_API_max_producers = 0;
     ctx->quiesce = NO_QUIESCE;
-    ctx->metalog_ctx = NULL; /* only set this after the metadata log has finished initializing */
     ctx->host = host;
 
     memset(&ctx->worker_config, 0, sizeof(ctx->worker_config));
@@ -918,11 +1100,11 @@ int rrdeng_init(RRDHOST *host, struct rrdengine_instance **ctxp, char *dbfiles_p
     if (ctx->worker_config.error) {
         goto error_after_rrdeng_worker;
     }
-    error = metalog_init(ctx);
-    if (error) {
-        error("Failed to initialize metadata log file event loop.");
-        goto error_after_rrdeng_worker;
-    }
+//    error = metalog_init(ctx);
+//    if (error) {
+//        error("Failed to initialize metadata log file event loop.");
+//        goto error_after_rrdeng_worker;
+//    }
 
     return 0;
 
@@ -1010,13 +1192,13 @@ RRDENG_SIZE_STATS rrdeng_size_statistics(struct rrdengine_instance *ctx) {
                 size_t points = descr->page_length / PAGE_POINT_SIZE_BYTES(descr);
 
                 if(likely(points > 1))
-                    update_every_usec = (descr->end_time - descr->start_time) / (points - 1);
+                    update_every_usec = (descr->end_time_ut - descr->start_time_ut) / (points - 1);
                 else {
                     update_every_usec = default_rrd_update_every * get_tier_grouping(ctx->tier) * USEC_PER_SEC;
                     stats.single_point_pages++;
                 }
 
-                time_t duration_secs = (time_t)((descr->end_time - descr->start_time + update_every_usec)/USEC_PER_SEC);
+                time_t duration_secs = (time_t)((descr->end_time_ut - descr->start_time_ut + update_every_usec)/USEC_PER_SEC);
 
                 stats.extents_pages++;
                 stats.pages_uncompressed_bytes += descr->page_length;
@@ -1028,11 +1210,11 @@ RRDENG_SIZE_STATS rrdeng_size_statistics(struct rrdengine_instance *ctx) {
                 stats.page_types[descr->type].pages_duration_secs += duration_secs;
                 stats.page_types[descr->type].points += points;
 
-                if(!stats.first_t || (descr->start_time - update_every_usec) < stats.first_t)
-                    stats.first_t = (descr->start_time - update_every_usec) / USEC_PER_SEC;
+                if(!stats.first_t || (descr->start_time_ut - update_every_usec) < stats.first_t)
+                    stats.first_t = (descr->start_time_ut - update_every_usec) / USEC_PER_SEC;
 
-                if(!stats.last_t || descr->end_time > stats.last_t)
-                    stats.last_t = descr->end_time / USEC_PER_SEC;
+                if(!stats.last_t || descr->end_time_ut > stats.last_t)
+                    stats.last_t = descr->end_time_ut / USEC_PER_SEC;
             }
         }
     }
@@ -1072,7 +1254,7 @@ RRDENG_SIZE_STATS rrdeng_size_statistics(struct rrdengine_instance *ctx) {
         }
     }
 
-    stats.sizeof_metric = struct_natural_alignment(sizeof(struct pg_cache_page_index));
+    stats.sizeof_metric = struct_natural_alignment(sizeof(struct pg_cache_page_index) + sizeof(struct pg_alignment));
     stats.sizeof_page = struct_natural_alignment(sizeof(struct rrdeng_page_descr));
     stats.sizeof_datafile = struct_natural_alignment(sizeof(struct rrdengine_datafile)) + struct_natural_alignment(sizeof(struct rrdengine_journalfile));
     stats.sizeof_page_in_cache = struct_natural_alignment(sizeof(struct page_cache_descr));
diff --git a/database/engine/rrdengineapi.h b/database/engine/rrdengineapi.h
index 509aa48ca..85375044f 100644
--- a/database/engine/rrdengineapi.h
+++ b/database/engine/rrdengineapi.h
@@ -25,58 +25,63 @@ extern size_t page_type_size[];
 #define PAGE_POINT_SIZE_BYTES(x) page_type_size[(x)->type]
 
 struct rrdeng_region_info {
-    time_t start_time;
+    time_t start_time_s;
     int update_every;
     unsigned points;
 };
 
-extern void *rrdeng_create_page(struct rrdengine_instance *ctx, uuid_t *id, struct rrdeng_page_descr **ret_descr);
-extern void rrdeng_commit_page(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr,
+void *rrdeng_create_page(struct rrdengine_instance *ctx, uuid_t *id, struct rrdeng_page_descr **ret_descr);
+void rrdeng_commit_page(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr,
                                Word_t page_correlation_id);
-extern void *rrdeng_get_latest_page(struct rrdengine_instance *ctx, uuid_t *id, void **handle);
-extern void *rrdeng_get_page(struct rrdengine_instance *ctx, uuid_t *id, usec_t point_in_time, void **handle);
-extern void rrdeng_put_page(struct rrdengine_instance *ctx, void *handle);
+void *rrdeng_get_latest_page(struct rrdengine_instance *ctx, uuid_t *id, void **handle);
+void *rrdeng_get_page(struct rrdengine_instance *ctx, uuid_t *id, usec_t point_in_time_ut, void **handle);
+void rrdeng_put_page(struct rrdengine_instance *ctx, void *handle);
 
-extern void rrdeng_generate_legacy_uuid(const char *dim_id, char *chart_id, uuid_t *ret_uuid);
-extern void rrdeng_convert_legacy_uuid_to_multihost(char machine_guid[GUID_LEN + 1], uuid_t *legacy_uuid,
+void rrdeng_generate_legacy_uuid(const char *dim_id, const char *chart_id, uuid_t *ret_uuid);
+void rrdeng_convert_legacy_uuid_to_multihost(char machine_guid[GUID_LEN + 1], uuid_t *legacy_uuid,
                                                     uuid_t *ret_uuid);
 
 
-extern STORAGE_METRIC_HANDLE *rrdeng_metric_init(RRDDIM *rd, STORAGE_INSTANCE *db_instance);
-extern void rrdeng_metric_free(STORAGE_METRIC_HANDLE *db_metric_handle);
+STORAGE_METRIC_HANDLE *rrdeng_metric_get_or_create(RRDDIM *rd, STORAGE_INSTANCE *db_instance, STORAGE_METRICS_GROUP *smg);
+STORAGE_METRIC_HANDLE *rrdeng_metric_get(STORAGE_INSTANCE *db_instance, uuid_t *uuid, STORAGE_METRICS_GROUP *smg);
+STORAGE_METRIC_HANDLE *rrdeng_metric_create(STORAGE_INSTANCE *db_instance, uuid_t *uuid, STORAGE_METRICS_GROUP *smg);
+STORAGE_METRIC_HANDLE *rrdeng_metric_get_legacy(STORAGE_INSTANCE *db_instance, const char *rd_id, const char *st_id, STORAGE_METRICS_GROUP *smg);
+void rrdeng_metric_release(STORAGE_METRIC_HANDLE *db_metric_handle);
+STORAGE_METRIC_HANDLE *rrdeng_metric_dup(STORAGE_METRIC_HANDLE *db_metric_handle);
 
-extern STORAGE_COLLECT_HANDLE *rrdeng_store_metric_init(STORAGE_METRIC_HANDLE *db_metric_handle);
-extern void rrdeng_store_metric_flush_current_page(STORAGE_COLLECT_HANDLE *collection_handle);
-extern void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle, usec_t point_in_time, NETDATA_DOUBLE n,
+STORAGE_COLLECT_HANDLE *rrdeng_store_metric_init(STORAGE_METRIC_HANDLE *db_metric_handle, uint32_t update_every);
+void rrdeng_store_metric_flush_current_page(STORAGE_COLLECT_HANDLE *collection_handle);
+void rrdeng_store_metric_change_collection_frequency(STORAGE_COLLECT_HANDLE *collection_handle, int update_every);
+void rrdeng_store_metric_next(STORAGE_COLLECT_HANDLE *collection_handle, usec_t point_in_time_ut, NETDATA_DOUBLE n,
                                      NETDATA_DOUBLE min_value,
                                      NETDATA_DOUBLE max_value,
                                      uint16_t count,
                                      uint16_t anomaly_count,
                                      SN_FLAGS flags);
-extern int rrdeng_store_metric_finalize(STORAGE_COLLECT_HANDLE *collection_handle);
+int rrdeng_store_metric_finalize(STORAGE_COLLECT_HANDLE *collection_handle);
 
-extern unsigned rrdeng_variable_step_boundaries(RRDSET *st, time_t start_time, time_t end_time,
-                                    struct rrdeng_region_info **region_info_arrayp, unsigned *max_intervalp, struct context_param *context_param_list);
+void rrdeng_load_metric_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct storage_engine_query_handle *rrdimm_handle,
+                                    time_t start_time_s, time_t end_time_s);
+STORAGE_POINT rrdeng_load_metric_next(struct storage_engine_query_handle *rrddim_handle);
 
-extern void rrdeng_load_metric_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct rrddim_query_handle *rrdimm_handle,
-                                    time_t start_time, time_t end_time, TIER_QUERY_FETCH tier_query_fetch_type);
-extern STORAGE_POINT rrdeng_load_metric_next(struct rrddim_query_handle *rrdimm_handle);
 
-extern int rrdeng_load_metric_is_finished(struct rrddim_query_handle *rrdimm_handle);
-extern void rrdeng_load_metric_finalize(struct rrddim_query_handle *rrdimm_handle);
-extern time_t rrdeng_metric_latest_time(STORAGE_METRIC_HANDLE *db_metric_handle);
-extern time_t rrdeng_metric_oldest_time(STORAGE_METRIC_HANDLE *db_metric_handle);
+int rrdeng_load_metric_is_finished(struct storage_engine_query_handle *rrdimm_handle);
+void rrdeng_load_metric_finalize(struct storage_engine_query_handle *rrdimm_handle);
+time_t rrdeng_metric_latest_time(STORAGE_METRIC_HANDLE *db_metric_handle);
+time_t rrdeng_metric_oldest_time(STORAGE_METRIC_HANDLE *db_metric_handle);
 
-extern void rrdeng_get_37_statistics(struct rrdengine_instance *ctx, unsigned long long *array);
+void rrdeng_get_37_statistics(struct rrdengine_instance *ctx, unsigned long long *array);
 
 /* must call once before using anything */
-extern int rrdeng_init(RRDHOST *host, struct rrdengine_instance **ctxp, char *dbfiles_path, unsigned page_cache_mb,
-                       unsigned disk_space_mb, int tier);
+int rrdeng_init(RRDHOST *host, struct rrdengine_instance **ctxp, char *dbfiles_path, unsigned page_cache_mb,
+                       unsigned disk_space_mb, size_t tier);
 
-extern int rrdeng_exit(struct rrdengine_instance *ctx);
-extern void rrdeng_prepare_exit(struct rrdengine_instance *ctx);
-extern int rrdeng_metric_latest_time_by_uuid(uuid_t *dim_uuid, time_t *first_entry_t, time_t *last_entry_t, int tier);
-extern int rrdeng_metric_retention_by_uuid(STORAGE_INSTANCE *si, uuid_t *dim_uuid, time_t *first_entry_t, time_t *last_entry_t);
+int rrdeng_exit(struct rrdengine_instance *ctx);
+void rrdeng_prepare_exit(struct rrdengine_instance *ctx);
+int rrdeng_metric_retention_by_uuid(STORAGE_INSTANCE *si, uuid_t *dim_uuid, time_t *first_entry_t, time_t *last_entry_t);
+
+extern STORAGE_METRICS_GROUP *rrdeng_metrics_group_get(STORAGE_INSTANCE *db_instance, uuid_t *uuid);
+extern void rrdeng_metrics_group_release(STORAGE_INSTANCE *db_instance, STORAGE_METRICS_GROUP *smg);
 
 typedef struct rrdengine_size_statistics {
     size_t default_granularity_secs;
@@ -134,6 +139,6 @@ typedef struct rrdengine_size_statistics {
     double average_page_size_bytes;
 } RRDENG_SIZE_STATS;
 
-extern RRDENG_SIZE_STATS rrdeng_size_statistics(struct rrdengine_instance *ctx);
+RRDENG_SIZE_STATS rrdeng_size_statistics(struct rrdengine_instance *ctx);
 
 #endif /* NETDATA_RRDENGINEAPI_H */
diff --git a/database/engine/rrdenginelib.c b/database/engine/rrdenginelib.c
index 287b86be8..58bd9c437 100644
--- a/database/engine/rrdenginelib.c
+++ b/database/engine/rrdenginelib.c
@@ -4,28 +4,45 @@
 #define BUFSIZE (512)
 
 /* Caller must hold descriptor lock */
-void print_page_cache_descr(struct rrdeng_page_descr *descr)
+void print_page_cache_descr(struct rrdeng_page_descr *descr, const char *msg, bool log_debug)
 {
-    struct page_cache_descr *pg_cache_descr = descr->pg_cache_descr;
-    char uuid_str[UUID_STR_LEN];
-    char str[BUFSIZE + 1];
-    int pos = 0;
+    if(log_debug && !(debug_flags & D_RRDENGINE))
+        return;
 
-    uuid_unparse_lower(*descr->id, uuid_str);
-    pos += snprintfz(str, BUFSIZE - pos, "page(%p) id=%s\n"
-                                    "--->len:%"PRIu32" time:%"PRIu64"->%"PRIu64" xt_offset:",
-                    pg_cache_descr->page, uuid_str,
-                    descr->page_length,
-                    (uint64_t)descr->start_time,
-                    (uint64_t)descr->end_time);
-    if (!descr->extent) {
-        pos += snprintfz(str + pos, BUFSIZE - pos, "N/A");
-    } else {
-        pos += snprintfz(str + pos, BUFSIZE - pos, "%"PRIu64, descr->extent->offset);
+    BUFFER *wb = buffer_create(512);
+
+    if(!descr) {
+        buffer_sprintf(wb, "DBENGINE: %s : descr is NULL", msg);
     }
+    else {
+        struct page_cache_descr *pg_cache_descr = descr->pg_cache_descr;
+        char uuid_str[UUID_STR_LEN];
+
+        uuid_unparse_lower(*descr->id, uuid_str);
+        buffer_sprintf(wb, "DBENGINE: %s : page(%p) metric:%s, len:%"PRIu32", time:%"PRIu64"->%"PRIu64", update_every:%u, type:%u, xt_offset:",
+                       msg,
+                       pg_cache_descr->page, uuid_str,
+                       descr->page_length,
+                       (uint64_t)descr->start_time_ut,
+                       (uint64_t)descr->end_time_ut,
+                       (uint32_t)descr->update_every_s,
+                       (uint32_t)descr->type
+                       );
+        if (!descr->extent) {
+            buffer_strcat(wb, "N/A");
+        } else {
+            buffer_sprintf(wb, "%"PRIu64, descr->extent->offset);
+        }
+
+        buffer_sprintf(wb, ", flags:0x%2.2lX refcnt:%u", pg_cache_descr->flags, pg_cache_descr->refcnt);
+    }
+
+    if(log_debug)
+        debug(D_RRDENGINE, "%s", buffer_tostring(wb));
+    else
+        internal_error(true, "%s", buffer_tostring(wb));
 
-    snprintfz(str + pos, BUFSIZE - pos, " flags:0x%2.2lX refcnt:%u\n\n", pg_cache_descr->flags, pg_cache_descr->refcnt);
-    debug(D_RRDENGINE, "%s", str);
+    buffer_free(wb);
 }
 
 void print_page_descr(struct rrdeng_page_descr *descr)
@@ -39,8 +56,8 @@ void print_page_descr(struct rrdeng_page_descr *descr)
                                      "--->len:%"PRIu32" time:%"PRIu64"->%"PRIu64" xt_offset:",
                      uuid_str,
                      descr->page_length,
-                     (uint64_t)descr->start_time,
-                     (uint64_t)descr->end_time);
+                     (uint64_t)descr->start_time_ut,
+                     (uint64_t)descr->end_time_ut);
     if (!descr->extent) {
         pos += snprintfz(str + pos, BUFSIZE - pos, "N/A");
     } else {
diff --git a/database/engine/rrdenginelib.h b/database/engine/rrdenginelib.h
index 32eebf103..6b1a15fb1 100644
--- a/database/engine/rrdenginelib.h
+++ b/database/engine/rrdenginelib.h
@@ -83,10 +83,10 @@ static inline void crc32set(void *crcp, uLong crc)
     *(uint32_t *)crcp = crc;
 }
 
-extern void print_page_cache_descr(struct rrdeng_page_descr *page_cache_descr);
-extern void print_page_descr(struct rrdeng_page_descr *descr);
-extern int check_file_properties(uv_file file, uint64_t *file_size, size_t min_size);
-extern int open_file_for_io(char *path, int flags, uv_file *file, int direct);
+void print_page_cache_descr(struct rrdeng_page_descr *descr, const char *msg, bool log_debug);
+void print_page_descr(struct rrdeng_page_descr *descr);
+int check_file_properties(uv_file file, uint64_t *file_size, size_t min_size);
+int open_file_for_io(char *path, int flags, uv_file *file, int direct);
 static inline int open_file_direct_io(char *path, int flags, uv_file *file)
 {
     return open_file_for_io(path, flags, file, 1);
@@ -95,8 +95,8 @@ static inline int open_file_buffered_io(char *path, int flags, uv_file *file)
 {
     return open_file_for_io(path, flags, file, 0);
 }
-extern char *get_rrdeng_statistics(struct rrdengine_instance *ctx, char *str, size_t size);
-extern int compute_multidb_diskspace();
-extern int is_legacy_child(const char *machine_guid);
+char *get_rrdeng_statistics(struct rrdengine_instance *ctx, char *str, size_t size);
+int compute_multidb_diskspace();
+int is_legacy_child(const char *machine_guid);
 
 #endif /* NETDATA_RRDENGINELIB_H */
diff --git a/database/engine/rrdenglocking.h b/database/engine/rrdenglocking.h
index 127ddc90c..078eab38b 100644
--- a/database/engine/rrdenglocking.h
+++ b/database/engine/rrdenglocking.h
@@ -8,10 +8,10 @@
 /* Forward declarations */
 struct page_cache_descr;
 
-extern struct page_cache_descr *rrdeng_create_pg_cache_descr(struct rrdengine_instance *ctx);
-extern void rrdeng_destroy_pg_cache_descr(struct rrdengine_instance *ctx, struct page_cache_descr *pg_cache_descr);
-extern void rrdeng_page_descr_mutex_lock(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
-extern void rrdeng_page_descr_mutex_unlock(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
-extern void rrdeng_try_deallocate_pg_cache_descr(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
+struct page_cache_descr *rrdeng_create_pg_cache_descr(struct rrdengine_instance *ctx);
+void rrdeng_destroy_pg_cache_descr(struct rrdengine_instance *ctx, struct page_cache_descr *pg_cache_descr);
+void rrdeng_page_descr_mutex_lock(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
+void rrdeng_page_descr_mutex_unlock(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
+void rrdeng_try_deallocate_pg_cache_descr(struct rrdengine_instance *ctx, struct rrdeng_page_descr *descr);
 
 #endif /* NETDATA_RRDENGLOCKING_H */
\ No newline at end of file
diff --git a/database/ram/rrddim_mem.c b/database/ram/rrddim_mem.c
index 3226d3c0d..43f32350b 100644
--- a/database/ram/rrddim_mem.c
+++ b/database/ram/rrddim_mem.c
@@ -1,22 +1,76 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include "rrddim_mem.h"
+#include "Judy.h"
+
+static Pvoid_t rrddim_JudyHS_array = NULL;
+static netdata_rwlock_t rrddim_JudyHS_rwlock = NETDATA_RWLOCK_INITIALIZER;
+
+// ----------------------------------------------------------------------------
+// metrics groups
+
+STORAGE_METRICS_GROUP *rrddim_metrics_group_get(STORAGE_INSTANCE *db_instance __maybe_unused, uuid_t *uuid __maybe_unused) {
+    return NULL;
+}
+
+void rrddim_metrics_group_release(STORAGE_INSTANCE *db_instance __maybe_unused, STORAGE_METRICS_GROUP *smg __maybe_unused) {
+    // if(!smg) return; // smg may be NULL
+    ;
+}
 
 // ----------------------------------------------------------------------------
 // RRDDIM legacy data collection functions
 
-STORAGE_METRIC_HANDLE *rrddim_metric_init(RRDDIM *rd, STORAGE_INSTANCE *db_instance __maybe_unused) {
+STORAGE_METRIC_HANDLE *
+rrddim_metric_get_or_create(RRDDIM *rd, STORAGE_INSTANCE *db_instance __maybe_unused, STORAGE_METRICS_GROUP *smg __maybe_unused) {
+    STORAGE_METRIC_HANDLE *t = rrddim_metric_get(db_instance, &rd->metric_uuid, smg);
+    if(!t) {
+        netdata_rwlock_wrlock(&rrddim_JudyHS_rwlock);
+        Pvoid_t *PValue = JudyHSIns(&rrddim_JudyHS_array, &rd->metric_uuid, sizeof(uuid_t), PJE0);
+        fatal_assert(NULL == *PValue);
+        *PValue = rd;
+        t = (STORAGE_METRIC_HANDLE *)rd;
+        netdata_rwlock_unlock(&rrddim_JudyHS_rwlock);
+    }
+
+    if((RRDDIM *)t != rd)
+        fatal("RRDDIM_MEM: incorrect pointer returned from index.");
+
     return (STORAGE_METRIC_HANDLE *)rd;
 }
 
-void rrddim_metric_free(STORAGE_METRIC_HANDLE *db_metric_handle __maybe_unused) {
-    ;
+STORAGE_METRIC_HANDLE *
+rrddim_metric_get(STORAGE_INSTANCE *db_instance __maybe_unused, uuid_t *uuid, STORAGE_METRICS_GROUP *smg __maybe_unused) {
+    RRDDIM *rd = NULL;
+    netdata_rwlock_rdlock(&rrddim_JudyHS_rwlock);
+    Pvoid_t *PValue = JudyHSGet(rrddim_JudyHS_array, uuid, sizeof(uuid_t));
+    if (likely(NULL != PValue))
+        rd = *PValue;
+    netdata_rwlock_unlock(&rrddim_JudyHS_rwlock);
+
+    return (STORAGE_METRIC_HANDLE *)rd;
+}
+
+STORAGE_METRIC_HANDLE *rrddim_metric_dup(STORAGE_METRIC_HANDLE *db_metric_handle) {
+    return db_metric_handle;
+}
+
+void rrddim_metric_release(STORAGE_METRIC_HANDLE *db_metric_handle __maybe_unused) {
+    RRDDIM *rd = (RRDDIM *)db_metric_handle;
+
+    netdata_rwlock_wrlock(&rrddim_JudyHS_rwlock);
+    JudyHSDel(&rrddim_JudyHS_array, &rd->metric_uuid, sizeof(uuid_t), PJE0);
+    netdata_rwlock_unlock(&rrddim_JudyHS_rwlock);
+}
+
+void rrddim_store_metric_change_collection_frequency(STORAGE_COLLECT_HANDLE *collection_handle, int update_every __maybe_unused) {
+    rrddim_store_metric_flush(collection_handle);
 }
 
-STORAGE_COLLECT_HANDLE *rrddim_collect_init(STORAGE_METRIC_HANDLE *db_metric_handle) {
+STORAGE_COLLECT_HANDLE *rrddim_collect_init(STORAGE_METRIC_HANDLE *db_metric_handle, uint32_t update_every __maybe_unused) {
     RRDDIM *rd = (RRDDIM *)db_metric_handle;
     rd->db[rd->rrdset->current_entry] = pack_storage_number(NAN, SN_FLAG_NONE);
-    struct mem_collect_handle *ch = calloc(1, sizeof(struct mem_collect_handle));
+    struct mem_collect_handle *ch = callocz(1, sizeof(struct mem_collect_handle));
     ch->rd = rd;
     return (STORAGE_COLLECT_HANDLE *)ch;
 }
@@ -41,12 +95,15 @@ void rrddim_collect_store_metric(STORAGE_COLLECT_HANDLE *collection_handle, usec
 
 void rrddim_store_metric_flush(STORAGE_COLLECT_HANDLE *collection_handle) {
     struct mem_collect_handle *ch = (struct mem_collect_handle *)collection_handle;
+
     RRDDIM *rd = ch->rd;
-    memset(rd->db, 0, rd->entries * sizeof(storage_number));
+    for(int i = 0; i < rd->rrdset->entries ;i++)
+        rd->db[i] = SN_EMPTY_SLOT;
+
 }
 
 int rrddim_collect_finalize(STORAGE_COLLECT_HANDLE *collection_handle) {
-    free(collection_handle);
+    freez(collection_handle);
     return 0;
 }
 
@@ -91,7 +148,7 @@ static inline size_t rrddim_time2slot(RRDDIM *rd, time_t t) {
     }
 
     if(unlikely(ret >= entries)) {
-        error("INTERNAL ERROR: rrddim_time2slot() on %s returns values outside entries", rd->name);
+        error("INTERNAL ERROR: rrddim_time2slot() on %s returns values outside entries", rrddim_name(rd));
         ret = entries - 1;
     }
 
@@ -119,12 +176,12 @@ static inline time_t rrddim_slot2time(RRDDIM *rd, size_t slot) {
         ret = last_entry_t - (time_t)(update_every * (last_slot - slot));
 
     if(unlikely(ret < first_entry_t)) {
-        error("INTERNAL ERROR: rrddim_slot2time() on %s returns time too far in the past", rd->name);
+        error("INTERNAL ERROR: rrddim_slot2time() on %s returns time too far in the past", rrddim_name(rd));
         ret = first_entry_t;
     }
 
     if(unlikely(ret > last_entry_t)) {
-        error("INTERNAL ERROR: rrddim_slot2time() on %s returns time into the future", rd->name);
+        error("INTERNAL ERROR: rrddim_slot2time() on %s returns time into the future", rrddim_name(rd));
         ret = last_entry_t;
     }
 
@@ -134,15 +191,13 @@ static inline time_t rrddim_slot2time(RRDDIM *rd, size_t slot) {
 // ----------------------------------------------------------------------------
 // RRDDIM legacy database query functions
 
-void rrddim_query_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct rrddim_query_handle *handle, time_t start_time, time_t end_time, TIER_QUERY_FETCH tier_query_fetch_type) {
-    UNUSED(tier_query_fetch_type);
-
+void rrddim_query_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct storage_engine_query_handle *handle, time_t start_time, time_t end_time) {
     RRDDIM *rd = (RRDDIM *)db_metric_handle;
 
     handle->rd = rd;
-    handle->start_time = start_time;
-    handle->end_time = end_time;
-    struct mem_query_handle* h = calloc(1, sizeof(struct mem_query_handle));
+    handle->start_time_s = start_time;
+    handle->end_time_s = end_time;
+    struct mem_query_handle* h = mallocz(sizeof(struct mem_query_handle));
     h->slot           = rrddim_time2slot(rd, start_time);
     h->last_slot      = rrddim_time2slot(rd, end_time);
     h->dt = rd->rrdset->update_every;
@@ -159,7 +214,7 @@ void rrddim_query_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct rrddim_qu
 // Returns the metric and sets its timestamp into current_time
 // IT IS REQUIRED TO **ALWAYS** SET ALL RETURN VALUES (current_time, end_time, flags)
 // IT IS REQUIRED TO **ALWAYS** KEEP TRACK OF TIME, EVEN OUTSIDE THE DATABASE BOUNDARIES
-STORAGE_POINT rrddim_query_next_metric(struct rrddim_query_handle *handle) {
+STORAGE_POINT rrddim_query_next_metric(struct storage_engine_query_handle *handle) {
     RRDDIM *rd = handle->rd;
     struct mem_query_handle* h = (struct mem_query_handle*)handle->handle;
     size_t entries = rd->rrdset->entries;
@@ -198,15 +253,15 @@ STORAGE_POINT rrddim_query_next_metric(struct rrddim_query_handle *handle) {
     return sp;
 }
 
-int rrddim_query_is_finished(struct rrddim_query_handle *handle) {
+int rrddim_query_is_finished(struct storage_engine_query_handle *handle) {
     struct mem_query_handle* h = (struct mem_query_handle*)handle->handle;
-    return (h->next_timestamp > handle->end_time);
+    return (h->next_timestamp > handle->end_time_s);
 }
 
-void rrddim_query_finalize(struct rrddim_query_handle *handle) {
+void rrddim_query_finalize(struct storage_engine_query_handle *handle) {
 #ifdef NETDATA_INTERNAL_CHECKS
     if(!rrddim_query_is_finished(handle))
-        error("QUERY: query for chart '%s' dimension '%s' has been stopped unfinished", handle->rd->rrdset->id, handle->rd->name);
+        error("QUERY: query for chart '%s' dimension '%s' has been stopped unfinished", rrdset_id(handle->rd->rrdset), rrddim_name(handle->rd));
 #endif
     freez(handle->handle);
 }
diff --git a/database/ram/rrddim_mem.h b/database/ram/rrddim_mem.h
index 400bdd0c2..297388f51 100644
--- a/database/ram/rrddim_mem.h
+++ b/database/ram/rrddim_mem.h
@@ -20,24 +20,30 @@ struct mem_query_handle {
     size_t last_slot;
 };
 
-extern STORAGE_METRIC_HANDLE *rrddim_metric_init(RRDDIM *rd, STORAGE_INSTANCE *db_instance);
-extern void rrddim_metric_free(STORAGE_METRIC_HANDLE *db_metric_handle);
+STORAGE_METRIC_HANDLE *rrddim_metric_get_or_create(RRDDIM *rd, STORAGE_INSTANCE *db_instance, STORAGE_METRICS_GROUP *smg);
+STORAGE_METRIC_HANDLE *rrddim_metric_get(STORAGE_INSTANCE *db_instance, uuid_t *uuid, STORAGE_METRICS_GROUP *smg);
+STORAGE_METRIC_HANDLE *rrddim_metric_dup(STORAGE_METRIC_HANDLE *db_metric_handle);
+void rrddim_metric_release(STORAGE_METRIC_HANDLE *db_metric_handle);
 
-extern STORAGE_COLLECT_HANDLE *rrddim_collect_init(STORAGE_METRIC_HANDLE *db_metric_handle);
-extern void rrddim_collect_store_metric(STORAGE_COLLECT_HANDLE *collection_handle, usec_t point_in_time, NETDATA_DOUBLE number,
+STORAGE_METRICS_GROUP *rrddim_metrics_group_get(STORAGE_INSTANCE *db_instance, uuid_t *uuid);
+void rrddim_metrics_group_release(STORAGE_INSTANCE *db_instance, STORAGE_METRICS_GROUP *smg);
+
+STORAGE_COLLECT_HANDLE *rrddim_collect_init(STORAGE_METRIC_HANDLE *db_metric_handle, uint32_t update_every);
+void rrddim_store_metric_change_collection_frequency(STORAGE_COLLECT_HANDLE *collection_handle, int update_every);
+void rrddim_collect_store_metric(STORAGE_COLLECT_HANDLE *collection_handle, usec_t point_in_time, NETDATA_DOUBLE number,
                                  NETDATA_DOUBLE min_value,
                                  NETDATA_DOUBLE max_value,
                                  uint16_t count,
                                  uint16_t anomaly_count,
                                  SN_FLAGS flags);
-extern void rrddim_store_metric_flush(STORAGE_COLLECT_HANDLE *collection_handle);
-extern int rrddim_collect_finalize(STORAGE_COLLECT_HANDLE *collection_handle);
-
-extern void rrddim_query_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct rrddim_query_handle *handle, time_t start_time, time_t end_time, TIER_QUERY_FETCH tier_query_fetch_type);
-extern STORAGE_POINT rrddim_query_next_metric(struct rrddim_query_handle *handle);
-extern int rrddim_query_is_finished(struct rrddim_query_handle *handle);
-extern void rrddim_query_finalize(struct rrddim_query_handle *handle);
-extern time_t rrddim_query_latest_time(STORAGE_METRIC_HANDLE *db_metric_handle);
-extern time_t rrddim_query_oldest_time(STORAGE_METRIC_HANDLE *db_metric_handle);
+void rrddim_store_metric_flush(STORAGE_COLLECT_HANDLE *collection_handle);
+int rrddim_collect_finalize(STORAGE_COLLECT_HANDLE *collection_handle);
+
+void rrddim_query_init(STORAGE_METRIC_HANDLE *db_metric_handle, struct storage_engine_query_handle *handle, time_t start_time, time_t end_time);
+STORAGE_POINT rrddim_query_next_metric(struct storage_engine_query_handle *handle);
+int rrddim_query_is_finished(struct storage_engine_query_handle *handle);
+void rrddim_query_finalize(struct storage_engine_query_handle *handle);
+time_t rrddim_query_latest_time(STORAGE_METRIC_HANDLE *db_metric_handle);
+time_t rrddim_query_oldest_time(STORAGE_METRIC_HANDLE *db_metric_handle);
 
 #endif
diff --git a/database/rrd.c b/database/rrd.c
index f91039ea5..df364419e 100644
--- a/database/rrd.c
+++ b/database/rrd.c
@@ -154,3 +154,15 @@ char *rrdset_cache_dir(RRDHOST *host, const char *id) {
     return ret;
 }
 
+// ----------------------------------------------------------------------------
+// RRD - string management
+
+STRING *rrd_string_strdupz(const char *s) {
+    if(unlikely(!s || !*s)) return string_strdupz(s);
+
+    char *tmp = strdupz(s);
+    json_fix_string(tmp);
+    STRING *ret = string_strdupz(tmp);
+    freez(tmp);
+    return ret;
+}
diff --git a/database/rrd.h b/database/rrd.h
index 605ff50bc..f071ee254 100644
--- a/database/rrd.h
+++ b/database/rrd.h
@@ -11,26 +11,40 @@ extern "C" {
 // to enable type checking at compile time
 typedef struct storage_instance STORAGE_INSTANCE;
 typedef struct storage_metric_handle STORAGE_METRIC_HANDLE;
+typedef struct storage_alignment STORAGE_METRICS_GROUP;
 
 // forward typedefs
 typedef struct rrdhost RRDHOST;
 typedef struct rrddim RRDDIM;
 typedef struct rrdset RRDSET;
-typedef struct rrdvar RRDVAR;
-typedef struct rrdsetvar RRDSETVAR;
-typedef struct rrddimvar RRDDIMVAR;
 typedef struct rrdcalc RRDCALC;
 typedef struct rrdcalctemplate RRDCALCTEMPLATE;
 typedef struct alarm_entry ALARM_ENTRY;
-typedef struct context_param CONTEXT_PARAM;
+
+typedef struct rrdfamily_acquired RRDFAMILY_ACQUIRED;
+typedef struct rrdvar_acquired RRDVAR_ACQUIRED;
+typedef struct rrdsetvar_acquired RRDSETVAR_ACQUIRED;
+typedef struct rrdcalc_acquired RRDCALC_ACQUIRED;
+
+typedef struct rrdhost_acquired RRDHOST_ACQUIRED;
+typedef struct rrdset_acquired RRDSET_ACQUIRED;
+typedef struct rrddim_acquired RRDDIM_ACQUIRED;
 
 typedef void *ml_host_t;
 typedef void *ml_dimension_t;
 
+typedef enum {
+    QUERY_SOURCE_UNKNOWN,
+    QUERY_SOURCE_API_DATA,
+    QUERY_SOURCE_API_BADGE,
+    QUERY_SOURCE_API_WEIGHTS,
+    QUERY_SOURCE_HEALTH,
+    QUERY_SOURCE_ML,
+    QUERY_SOURCE_UNITTEST,
+} QUERY_SOURCE;
+
 // forward declarations
 struct rrddim_tier;
-struct rrdset_volatile;
-struct context_param;
 
 #ifdef ENABLE_DBENGINE
 struct rrdeng_page_descr;
@@ -51,8 +65,10 @@ struct pg_cache_page_index;
 #include "sqlite/sqlite_health.h"
 #include "rrdcontext.h"
 
-extern int storage_tiers;
-extern int storage_tiers_grouping_iterations[RRD_STORAGE_TIERS];
+extern bool unittest_running;
+extern bool dbengine_enabled;
+extern size_t storage_tiers;
+extern size_t storage_tiers_grouping_iterations[RRD_STORAGE_TIERS];
 
 typedef enum {
     RRD_BACKFILL_NONE,
@@ -75,11 +91,6 @@ struct context_param {
     uint8_t flags;
 };
 
-#define META_CHART_UPDATED 1
-#define META_PLUGIN_UPDATED 2
-#define META_MODULE_UPDATED 4
-#define META_CHART_ACTIVATED 8
-
 #define UPDATE_EVERY 1
 #define UPDATE_EVERY_MAX 3600
 
@@ -122,7 +133,9 @@ typedef enum rrd_memory_mode {
     RRD_MEMORY_MODE_MAP  = 2,
     RRD_MEMORY_MODE_SAVE = 3,
     RRD_MEMORY_MODE_ALLOC = 4,
-    RRD_MEMORY_MODE_DBENGINE = 5
+    RRD_MEMORY_MODE_DBENGINE = 5,
+
+    // this is 8-bit
 } RRD_MEMORY_MODE;
 
 #define RRD_MEMORY_MODE_NONE_NAME "none"
@@ -134,8 +147,8 @@ typedef enum rrd_memory_mode {
 
 extern RRD_MEMORY_MODE default_rrd_memory_mode;
 
-extern const char *rrd_memory_mode_name(RRD_MEMORY_MODE id);
-extern RRD_MEMORY_MODE rrd_memory_mode_id(const char *name);
+const char *rrd_memory_mode_name(RRD_MEMORY_MODE id);
+RRD_MEMORY_MODE rrd_memory_mode_id(const char *name);
 
 
 // ----------------------------------------------------------------------------
@@ -145,7 +158,9 @@ typedef enum rrd_algorithm {
     RRD_ALGORITHM_ABSOLUTE              = 0,
     RRD_ALGORITHM_INCREMENTAL           = 1,
     RRD_ALGORITHM_PCENT_OVER_DIFF_TOTAL = 2,
-    RRD_ALGORITHM_PCENT_OVER_ROW_TOTAL  = 3
+    RRD_ALGORITHM_PCENT_OVER_ROW_TOTAL  = 3,
+
+    // this is 8-bit
 } RRD_ALGORITHM;
 
 #define RRD_ALGORITHM_ABSOLUTE_NAME                "absolute"
@@ -153,43 +168,50 @@ typedef enum rrd_algorithm {
 #define RRD_ALGORITHM_PCENT_OVER_DIFF_TOTAL_NAME   "percentage-of-incremental-row"
 #define RRD_ALGORITHM_PCENT_OVER_ROW_TOTAL_NAME    "percentage-of-absolute-row"
 
-extern RRD_ALGORITHM rrd_algorithm_id(const char *name);
-extern const char *rrd_algorithm_name(RRD_ALGORITHM algorithm);
+RRD_ALGORITHM rrd_algorithm_id(const char *name);
+const char *rrd_algorithm_name(RRD_ALGORITHM algorithm);
 
 // ----------------------------------------------------------------------------
 // RRD FAMILY
 
-struct rrdfamily {
-    avl_t avl;
+const RRDFAMILY_ACQUIRED *rrdfamily_add_and_acquire(RRDHOST *host, const char *id);
+void rrdfamily_release(RRDHOST *host, const RRDFAMILY_ACQUIRED *rfa);
+void rrdfamily_index_init(RRDHOST *host);
+void rrdfamily_index_destroy(RRDHOST *host);
+DICTIONARY *rrdfamily_rrdvars_dict(const RRDFAMILY_ACQUIRED *rf);
 
-    const char *family;
-    uint32_t hash_family;
 
-    size_t use_count;
+// ----------------------------------------------------------------------------
+// flags & options
 
-    avl_tree_lock rrdvar_root_index;
-};
-typedef struct rrdfamily RRDFAMILY;
+// options are permanent configuration options (no atomics to alter/access them)
+typedef enum rrddim_options {
+    RRDDIM_OPTION_NONE                              = 0,
+    RRDDIM_OPTION_HIDDEN                            = (1 << 0), // this dimension will not be offered to callers
+    RRDDIM_OPTION_DONT_DETECT_RESETS_OR_OVERFLOWS   = (1 << 1), // do not offer RESET or OVERFLOW info to callers
+    RRDDIM_OPTION_BACKFILLED_HIGH_TIERS             = (1 << 2), // when set, we have backfilled higher tiers
 
+    // this is 8-bit
+} RRDDIM_OPTIONS;
 
-// ----------------------------------------------------------------------------
-// flags
-// use this for configuration flags, not for state control
-// flags are set/unset in a manner that is not thread safe
-// and may lead to missing information.
+#define rrddim_option_check(rd, option) ((rd)->options & (option))
+#define rrddim_option_set(rd, option)   (rd)->options |= (option)
+#define rrddim_option_clear(rd, option) (rd)->options &= ~(option)
 
+// flags are runtime changing status flags (atomics are required to alter/access them)
 typedef enum rrddim_flags {
     RRDDIM_FLAG_NONE                            = 0,
-    RRDDIM_FLAG_HIDDEN                          = (1 << 0),  // this dimension will not be offered to callers
-    RRDDIM_FLAG_DONT_DETECT_RESETS_OR_OVERFLOWS = (1 << 1),  // do not offer RESET or OVERFLOW info to callers
+    RRDDIM_FLAG_PENDING_HEALTH_INITIALIZATION   = (1 << 0),
+
     RRDDIM_FLAG_OBSOLETE                        = (1 << 2),  // this is marked by the collector/module as obsolete
-    // No new values have been collected for this dimension since agent start or it was marked RRDDIM_FLAG_OBSOLETE at
+    // No new values have been collected for this dimension since agent start, or it was marked RRDDIM_FLAG_OBSOLETE at
     // least rrdset_free_obsolete_time seconds ago.
     RRDDIM_FLAG_ARCHIVED                        = (1 << 3),
-    RRDDIM_FLAG_ACLK                            = (1 << 4),
+    RRDDIM_FLAG_METADATA_UPDATE                 = (1 << 4),  // Metadata needs to go to the database
 
-    RRDDIM_FLAG_PENDING_FOREACH_ALARM           = (1 << 5), // set when foreach alarm has not been initialized yet
     RRDDIM_FLAG_META_HIDDEN                     = (1 << 6), // Status of hidden option in the metadata database
+
+    // this is 8 bit
 } RRDDIM_FLAGS;
 
 #define rrddim_flag_check(rd, flag) (__atomic_load_n(&((rd)->flags), __ATOMIC_SEQ_CST) & (flag))
@@ -211,62 +233,55 @@ typedef enum rrdlabel_source {
 
 #define RRDLABEL_FLAG_INTERNAL (RRDLABEL_FLAG_OLD | RRDLABEL_FLAG_NEW | RRDLABEL_FLAG_PERMANENT)
 
-extern DICTIONARY *rrdlabels_create(void);
-extern void rrdlabels_destroy(DICTIONARY *labels_dict);
-extern void rrdlabels_add(DICTIONARY *dict, const char *name, const char *value, RRDLABEL_SRC ls);
-extern void rrdlabels_add_pair(DICTIONARY *dict, const char *string, RRDLABEL_SRC ls);
-extern void rrdlabels_get_value_to_buffer_or_null(DICTIONARY *labels, BUFFER *wb, const char *key, const char *quote, const char *null);
+size_t text_sanitize(unsigned char *dst, const unsigned char *src, size_t dst_size, unsigned char *char_map, bool utf, const char *empty, size_t *multibyte_length);
 
-extern void rrdlabels_unmark_all(DICTIONARY *labels);
-extern void rrdlabels_remove_all_unmarked(DICTIONARY *labels);
+DICTIONARY *rrdlabels_create(void);
+void rrdlabels_destroy(DICTIONARY *labels_dict);
+void rrdlabels_add(DICTIONARY *dict, const char *name, const char *value, RRDLABEL_SRC ls);
+void rrdlabels_add_pair(DICTIONARY *dict, const char *string, RRDLABEL_SRC ls);
+void rrdlabels_get_value_to_buffer_or_null(DICTIONARY *labels, BUFFER *wb, const char *key, const char *quote, const char *null);
+void rrdlabels_get_value_to_char_or_null(DICTIONARY *labels, char **value, const char *key);
+void rrdlabels_flush(DICTIONARY *labels_dict);
 
-extern int rrdlabels_walkthrough_read(DICTIONARY *labels, int (*callback)(const char *name, const char *value, RRDLABEL_SRC ls, void *data), void *data);
-extern int rrdlabels_sorted_walkthrough_read(DICTIONARY *labels, int (*callback)(const char *name, const char *value, RRDLABEL_SRC ls, void *data), void *data);
+void rrdlabels_unmark_all(DICTIONARY *labels);
+void rrdlabels_remove_all_unmarked(DICTIONARY *labels);
 
-extern void rrdlabels_log_to_buffer(DICTIONARY *labels, BUFFER *wb);
-extern bool rrdlabels_match_simple_pattern(DICTIONARY *labels, const char *simple_pattern_txt);
-extern bool rrdlabels_match_simple_pattern_parsed(DICTIONARY *labels, SIMPLE_PATTERN *pattern, char equal);
-extern int rrdlabels_to_buffer(DICTIONARY *labels, BUFFER *wb, const char *before_each, const char *equal, const char *quote, const char *between_them, bool (*filter_callback)(const char *name, const char *value, RRDLABEL_SRC ls, void *data), void *filter_data, void (*name_sanitizer)(char *dst, const char *src, size_t dst_size), void (*value_sanitizer)(char *dst, const char *src, size_t dst_size));
+int rrdlabels_walkthrough_read(DICTIONARY *labels, int (*callback)(const char *name, const char *value, RRDLABEL_SRC ls, void *data), void *data);
+int rrdlabels_sorted_walkthrough_read(DICTIONARY *labels, int (*callback)(const char *name, const char *value, RRDLABEL_SRC ls, void *data), void *data);
 
-extern void rrdlabels_migrate_to_these(DICTIONARY *dst, DICTIONARY *src);
-extern void rrdlabels_copy(DICTIONARY *dst, DICTIONARY *src);
+void rrdlabels_log_to_buffer(DICTIONARY *labels, BUFFER *wb);
+bool rrdlabels_match_simple_pattern(DICTIONARY *labels, const char *simple_pattern_txt);
+bool rrdlabels_match_simple_pattern_parsed(DICTIONARY *labels, SIMPLE_PATTERN *pattern, char equal);
+int rrdlabels_to_buffer(DICTIONARY *labels, BUFFER *wb, const char *before_each, const char *equal, const char *quote, const char *between_them, bool (*filter_callback)(const char *name, const char *value, RRDLABEL_SRC ls, void *data), void *filter_data, void (*name_sanitizer)(char *dst, const char *src, size_t dst_size), void (*value_sanitizer)(char *dst, const char *src, size_t dst_size));
 
-void reload_host_labels(void);
-extern void rrdset_update_rrdlabels(RRDSET *st, DICTIONARY *new_rrdlabels);
+void rrdlabels_migrate_to_these(DICTIONARY *dst, DICTIONARY *src);
+void rrdlabels_copy(DICTIONARY *dst, DICTIONARY *src);
 
-extern int rrdlabels_unittest(void);
+void reload_host_labels(void);
+void rrdset_update_rrdlabels(RRDSET *st, DICTIONARY *new_rrdlabels);
+void rrdset_save_rrdlabels_to_sql(RRDSET *st);
+void rrdhost_set_is_parent_label(int count);
+int rrdlabels_unittest(void);
 
 // unfortunately this break when defined in exporting_engine.h
-extern bool exporting_labels_filter_callback(const char *name, const char *value, RRDLABEL_SRC ls, void *data);
+bool exporting_labels_filter_callback(const char *name, const char *value, RRDLABEL_SRC ls, void *data);
 
 // ----------------------------------------------------------------------------
 // RRD DIMENSION - this is a metric
 
 struct rrddim {
-    // ------------------------------------------------------------------------
-    // binary indexing structures
-
-    avl_t avl;                                      // the binary index - this has to be first member!
-
     uuid_t metric_uuid;                             // global UUID for this metric (unique_across hosts)
 
     // ------------------------------------------------------------------------
-    // the dimension definition
-
-    const char *id;                                 // the id of this dimension (for internal identification)
-    const char *name;                               // the name of this dimension (as presented to user)
-                                                    // this is a pointer to the config structure
-                                                    // since the config always has a higher priority
-                                                    // (the user overwrites the name of the charts)
-    uint32_t hash;                                  // a simple hash of the id, to speed up searching / indexing
-                                                    // instead of strcmp() every item in the binary index
-                                                    // we first compare the hashes
-    uint32_t hash_name;                             // a simple hash of the name
+    // dimension definition
 
+    STRING *id;                                     // the id of this dimension (for internal identification)
+    STRING *name;                                   // the name of this dimension (as presented to user)
 
-    RRD_ALGORITHM algorithm;                        // the algorithm that is applied to add new collected values
-    RRD_MEMORY_MODE rrd_memory_mode;                // the memory mode for this dimension
-    RRDDIM_FLAGS flags;                             // configuration flags for the dimension
+    RRD_ALGORITHM algorithm:8;                      // the algorithm that is applied to add new collected values
+    RRDDIM_OPTIONS options:8;                       // permanent configuration options
+    RRD_MEMORY_MODE rrd_memory_mode:8;              // the memory mode for this dimension
+    /*RRDDIM_FLAGS*/ uint8_t flags;                 // run time changing status flags
 
     bool updated;                                   // 1 when the dimension has been updated since the last processing
     bool exposed;                                   // 1 when set what have sent this dimension to the central netdata
@@ -274,20 +289,31 @@ struct rrddim {
     collected_number multiplier;                    // the multiplier of the collected values
     collected_number divisor;                       // the divider of the collected values
 
+    int update_every;                               // every how many seconds is this updated
+                                                    // TODO - remove update_every from rrddim
+                                                    //        it is always the same in rrdset
+
     // ------------------------------------------------------------------------
-    // members for temporary data we need for calculations
+    // operational state members
 
-    struct timeval last_collected_time;             // when was this dimension last updated
-                                                    // this is actual date time we updated the last_collected_value
-                                                    // THIS IS DIFFERENT FROM THE SAME MEMBER OF RRDSET
+    ml_dimension_t ml_dimension;                    // machine learning data about this dimension
 
-#ifdef ENABLE_ACLK
-    int aclk_live_status;
-#endif
-    ml_dimension_t ml_dimension;
+    // ------------------------------------------------------------------------
+    // linking to siblings and parents
+
+    struct rrdset *rrdset;
+
+    RRDMETRIC_ACQUIRED *rrdmetric;                  // the rrdmetric of this dimension
+
+    // ------------------------------------------------------------------------
+    // data collection members
 
     struct rrddim_tier *tiers[RRD_STORAGE_TIERS];   // our tiers of databases
 
+    struct timeval last_collected_time;             // when was this dimension last updated
+                                                    // this is actual date time we updated the last_collected_value
+                                                    // THIS IS DIFFERENT FROM THE SAME MEMBER OF RRDSET
+
     size_t collections_counter;                     // the number of times we added values to this rrddim
     collected_number collected_value_max;           // the absolute maximum of the collected value
 
@@ -298,68 +324,42 @@ struct rrddim {
     collected_number collected_value;               // the current value, as collected - resets to 0 after being used
     collected_number last_collected_value;          // the last value that was collected, after being processed
 
-    // the *_volume members are used to calculate the accuracy of the rounding done by the
-    // storage number - they are printed to debug.log when debug is enabled for a set.
-    NETDATA_DOUBLE collected_volume;                // the sum of all collected values so far
-    NETDATA_DOUBLE stored_volume;                   // the sum of all stored values so far
-
-    struct rrddim *next;                            // linking of dimensions within the same data set
-    struct rrdset *rrdset;
-    RRDMETRIC_ACQUIRED *rrdmetric;                  // the rrdmetric of this dimension
+#ifdef NETDATA_LOG_COLLECTION_ERRORS
+    usec_t rrddim_store_metric_last_ut;             // the timestamp we last called rrddim_store_metric()
+    size_t rrddim_store_metric_count;               // the rrddim_store_metric() counter
+    const char *rrddim_store_metric_last_caller;    // the name of the function that last called rrddim_store_metric()
+#endif
 
     // ------------------------------------------------------------------------
-    // members for checking the data when loading from disk
-
-    long entries;                                   // how many entries this dimension has in ram
-                                                    // this is the same to the entries of the data set
-                                                    // we set it here, to check the data when we load it from disk.
-
-    int update_every;                               // every how many seconds is this updated
+    // db mode RAM, SAVE, MAP, ALLOC, NONE specifics
+    // TODO - they should be managed by storage engine
+    //        (RRDDIM_DB_STATE ptr to an undefined structure, and a call to clean this up during destruction)
 
     size_t memsize;                                 // the memory allocated for this dimension (without RRDDIM)
-
-    struct rrddimvar *variables;
-
-    // ------------------------------------------------------------------------
-    // the values stored in this dimension, using our floating point numbers
-
     void *rd_on_file;                               // pointer to the header written on disk
     storage_number *db;                             // the array of values
 };
 
+#define rrddim_id(rd) string2str((rd)->id)
+#define rrddim_name(rd) string2str((rd) ->name)
+
 // returns the RRDDIM cache filename, or NULL if it does not exist
-extern const char *rrddim_cache_filename(RRDDIM *rd);
+const char *rrddim_cache_filename(RRDDIM *rd);
 
 // updated the header with the latest RRDDIM value, for memory mode MAP and SAVE
-extern void rrddim_memory_file_update(RRDDIM *rd);
+void rrddim_memory_file_update(RRDDIM *rd);
 
 // free the memory file structures for memory mode MAP and SAVE
-extern void rrddim_memory_file_free(RRDDIM *rd);
+void rrddim_memory_file_free(RRDDIM *rd);
 
-extern bool rrddim_memory_load_or_create_map_save(RRDSET *st, RRDDIM *rd, RRD_MEMORY_MODE memory_mode);
+bool rrddim_memory_load_or_create_map_save(RRDSET *st, RRDDIM *rd, RRD_MEMORY_MODE memory_mode);
 
 // return the v019 header size of RRDDIM files
-extern size_t rrddim_memory_file_header_size(void);
-
-extern void rrddim_memory_file_save(RRDDIM *rd);
+size_t rrddim_memory_file_header_size(void);
 
-// ----------------------------------------------------------------------------
-// engine-specific iterator state for dimension data collection
-typedef struct storage_collect_handle STORAGE_COLLECT_HANDLE;
-
-// ----------------------------------------------------------------------------
-// engine-specific iterator state for dimension data queries
-typedef struct storage_query_handle STORAGE_QUERY_HANDLE;
+void rrddim_memory_file_save(RRDDIM *rd);
 
 // ----------------------------------------------------------------------------
-// iterator state for RRD dimension data queries
-struct rrddim_query_handle {
-    RRDDIM *rd;
-    time_t start_time;
-    time_t end_time;
-    TIER_QUERY_FETCH tier_query_fetch_type;
-    STORAGE_QUERY_HANDLE* handle;
-};
 
 typedef struct storage_point {
     NETDATA_DOUBLE min;     // when count > 1, this is the minimum among them
@@ -397,11 +397,19 @@ typedef struct storage_point {
 #define storage_point_is_unset(x) (!(x).count)
 #define storage_point_is_empty(x) (!netdata_double_isnumber((x).sum))
 
+// ----------------------------------------------------------------------------
+// engine-specific iterator state for dimension data collection
+typedef struct storage_collect_handle STORAGE_COLLECT_HANDLE;
+
+// ----------------------------------------------------------------------------
+// engine-specific iterator state for dimension data queries
+typedef struct storage_query_handle STORAGE_QUERY_HANDLE;
+
 // ------------------------------------------------------------------------
 // function pointers that handle data collection
-struct rrddim_collect_ops {
+struct storage_engine_collect_ops {
     // an initialization function to run before starting collection
-    STORAGE_COLLECT_HANDLE *(*init)(STORAGE_METRIC_HANDLE *db_metric_handle);
+    STORAGE_COLLECT_HANDLE *(*init)(STORAGE_METRIC_HANDLE *db_metric_handle, uint32_t update_every);
 
     // run this to store each metric into the database
     void (*store_metric)(STORAGE_COLLECT_HANDLE *collection_handle, usec_t point_in_time, NETDATA_DOUBLE number, NETDATA_DOUBLE min_value,
@@ -410,24 +418,38 @@ struct rrddim_collect_ops {
     // run this to flush / reset the current data collection sequence
     void (*flush)(STORAGE_COLLECT_HANDLE *collection_handle);
 
-    // an finalization function to run after collection is over
+    // a finalization function to run after collection is over
     // returns 1 if it's safe to delete the dimension
     int (*finalize)(STORAGE_COLLECT_HANDLE *collection_handle);
+
+    void (*change_collection_frequency)(STORAGE_COLLECT_HANDLE *collection_handle, int update_every);
+
+    STORAGE_METRICS_GROUP *(*metrics_group_get)(STORAGE_INSTANCE *db_instance, uuid_t *uuid);
+    void (*metrics_group_release)(STORAGE_INSTANCE *db_instance, STORAGE_METRICS_GROUP *sa);
+};
+
+// ----------------------------------------------------------------------------
+// iterator state for RRD dimension data queries
+struct storage_engine_query_handle {
+    RRDDIM *rd;
+    time_t start_time_s;
+    time_t end_time_s;
+    STORAGE_QUERY_HANDLE* handle;
 };
 
 // function pointers that handle database queries
-struct rrddim_query_ops {
+struct storage_engine_query_ops {
     // run this before starting a series of next_metric() database queries
-    void (*init)(STORAGE_METRIC_HANDLE *db_metric_handle, struct rrddim_query_handle *handle, time_t start_time, time_t end_time, TIER_QUERY_FETCH tier_query_fetch_type);
+    void (*init)(STORAGE_METRIC_HANDLE *db_metric_handle, struct storage_engine_query_handle *handle, time_t start_time, time_t end_time);
 
     // run this to load each metric number from the database
-    STORAGE_POINT (*next_metric)(struct rrddim_query_handle *handle);
+    STORAGE_POINT (*next_metric)(struct storage_engine_query_handle *handle);
 
     // run this to test if the series of next_metric() database queries is finished
-    int (*is_finished)(struct rrddim_query_handle *handle);
+    int (*is_finished)(struct storage_engine_query_handle *handle);
 
     // run this after finishing a series of load_metric() database queries
-    void (*finalize)(struct rrddim_query_handle *handle);
+    void (*finalize)(struct storage_engine_query_handle *handle);
 
     // get the timestamp of the last entry of this metric
     time_t (*latest_time)(STORAGE_METRIC_HANDLE *db_metric_handle);
@@ -436,45 +458,60 @@ struct rrddim_query_ops {
     time_t (*oldest_time)(STORAGE_METRIC_HANDLE *db_metric_handle);
 };
 
+typedef struct storage_engine STORAGE_ENGINE;
+
+// ------------------------------------------------------------------------
+// function pointers for all APIs provided by a storage engine
+typedef struct storage_engine_api {
+    // metric management
+    STORAGE_METRIC_HANDLE *(*metric_get)(STORAGE_INSTANCE *instance, uuid_t *uuid, STORAGE_METRICS_GROUP *smg);
+    STORAGE_METRIC_HANDLE *(*metric_get_or_create)(RRDDIM *rd, STORAGE_INSTANCE *instance, STORAGE_METRICS_GROUP *smg);
+    void (*metric_release)(STORAGE_METRIC_HANDLE *);
+    STORAGE_METRIC_HANDLE *(*metric_dup)(STORAGE_METRIC_HANDLE *);
+
+    // operations
+    struct storage_engine_collect_ops collect_ops;
+    struct storage_engine_query_ops query_ops;
+} STORAGE_ENGINE_API;
+
+struct storage_engine {
+    RRD_MEMORY_MODE id;
+    const char* name;
+    STORAGE_ENGINE_API api;
+};
+
+STORAGE_ENGINE* storage_engine_get(RRD_MEMORY_MODE mmode);
+STORAGE_ENGINE* storage_engine_find(const char* name);
 
 // ----------------------------------------------------------------------------
 // Storage tier data for every dimension
 
 struct rrddim_tier {
-    int tier_grouping;
-    RRD_MEMORY_MODE mode;                           // the memory mode of this tier
-    RRD_BACKFILL backfill;                          // backfilling configuration
+    size_t tier_grouping;
     STORAGE_METRIC_HANDLE *db_metric_handle;        // the metric handle inside the database
     STORAGE_COLLECT_HANDLE *db_collection_handle;   // the data collection handle
     STORAGE_POINT virtual_point;
     time_t next_point_time;
-    usec_t last_collected_ut;
-    struct rrddim_collect_ops collect_ops;
-    struct rrddim_query_ops query_ops;
+    struct storage_engine_collect_ops *collect_ops;
+    struct storage_engine_query_ops *query_ops;
 };
 
-extern void rrdr_fill_tier_gap_from_smaller_tiers(RRDDIM *rd, int tier, time_t now);
-
-// ----------------------------------------------------------------------------
-// volatile state per chart
-struct rrdset_volatile {
-    char *old_title;
-    char *old_units;
-    char *old_context;
-    uuid_t hash_id;
-    DICTIONARY *chart_labels;
-    bool is_ar_chart;
-};
+void rrdr_fill_tier_gap_from_smaller_tiers(RRDDIM *rd, size_t tier, time_t now);
 
 // ----------------------------------------------------------------------------
 // these loop macros make sure the linked list is accessed with the right lock
 
 #define rrddim_foreach_read(rd, st) \
-    for((rd) = (st)->dimensions, rrdset_check_rdlock(st); (rd) ; (rd) = (rd)->next)
+    dfe_start_read((st)->rrddim_root_index, rd)
 
 #define rrddim_foreach_write(rd, st) \
-    for((rd) = (st)->dimensions, rrdset_check_wrlock(st); (rd) ; (rd) = (rd)->next)
+    dfe_start_write((st)->rrddim_root_index, rd)
 
+#define rrddim_foreach_reentrant(rd, st) \
+    dfe_start_reentrant((st)->rrddim_root_index, rd)
+
+#define rrddim_foreach_done(rd) \
+    dfe_done(rd)
 
 // ----------------------------------------------------------------------------
 // RRDSET - this is a chart
@@ -484,166 +521,213 @@ struct rrdset_volatile {
 // and may lead to missing information.
 
 typedef enum rrdset_flags {
-    RRDSET_FLAG_DETAIL              = 1 << 1, // if set, the data set should be considered as a detail of another
-                                              // (the master data set should be the one that has the same family and is not detail)
-    RRDSET_FLAG_DEBUG               = 1 << 2, // enables or disables debugging for a chart
-    RRDSET_FLAG_OBSOLETE            = 1 << 3, // this is marked by the collector/module as obsolete
-    RRDSET_FLAG_EXPORTING_SEND      = 1 << 4, // if set, this chart should be sent to Prometheus web API and external databases
-    RRDSET_FLAG_EXPORTING_IGNORE    = 1 << 5, // if set, this chart should not be sent to Prometheus web API and external databases
-    RRDSET_FLAG_UPSTREAM_SEND       = 1 << 6, // if set, this chart should be sent upstream (streaming)
-    RRDSET_FLAG_UPSTREAM_IGNORE     = 1 << 7, // if set, this chart should not be sent upstream (streaming)
-    RRDSET_FLAG_UPSTREAM_EXPOSED    = 1 << 8, // if set, we have sent this chart definition to netdata parent (streaming)
-    RRDSET_FLAG_STORE_FIRST         = 1 << 9, // if set, do not eliminate the first collection during interpolation
-    RRDSET_FLAG_HETEROGENEOUS       = 1 << 10, // if set, the chart is not homogeneous (dimensions in it have multiple algorithms, multipliers or dividers)
-    RRDSET_FLAG_HOMOGENEOUS_CHECK   = 1 << 11, // if set, the chart should be checked to determine if the dimensions are homogeneous
-    RRDSET_FLAG_HIDDEN              = 1 << 12, // if set, do not show this chart on the dashboard, but use it for exporting
-    RRDSET_FLAG_SYNC_CLOCK          = 1 << 13, // if set, microseconds on next data collection will be ignored (the chart will be synced to now)
-    RRDSET_FLAG_OBSOLETE_DIMENSIONS = 1 << 14, // this is marked by the collector/module when a chart has obsolete dimensions
-    // No new values have been collected for this chart since agent start or it was marked RRDSET_FLAG_OBSOLETE at
-    // least rrdset_free_obsolete_time seconds ago.
-    RRDSET_FLAG_ARCHIVED            = 1 << 15,
-    RRDSET_FLAG_ACLK                = 1 << 16,
-    RRDSET_FLAG_PENDING_FOREACH_ALARMS = 1 << 17, // contains dims with uninitialized foreach alarms
-    RRDSET_FLAG_ANOMALY_DETECTION   = 1 << 18 // flag to identify anomaly detection charts.
+    RRDSET_FLAG_DETAIL                           = (1 << 1),  // if set, the data set should be considered as a detail of another
+                                                              // (the master data set should be the one that has the same family and is not detail)
+    RRDSET_FLAG_DEBUG                            = (1 << 2),  // enables or disables debugging for a chart
+    RRDSET_FLAG_OBSOLETE                         = (1 << 3),  // this is marked by the collector/module as obsolete
+    RRDSET_FLAG_EXPORTING_SEND                   = (1 << 4),  // if set, this chart should be sent to Prometheus web API and external databases
+    RRDSET_FLAG_EXPORTING_IGNORE                 = (1 << 5),  // if set, this chart should not be sent to Prometheus web API and external databases
+
+    RRDSET_FLAG_UPSTREAM_SEND                    = (1 << 6),  // if set, this chart should be sent upstream (streaming)
+    RRDSET_FLAG_UPSTREAM_IGNORE                  = (1 << 7),  // if set, this chart should not be sent upstream (streaming)
+    RRDSET_FLAG_UPSTREAM_EXPOSED                 = (1 << 8),  // if set, we have sent this chart definition to netdata parent (streaming)
+
+    RRDSET_FLAG_STORE_FIRST                      = (1 << 9),  // if set, do not eliminate the first collection during interpolation
+    RRDSET_FLAG_HETEROGENEOUS                    = (1 << 10), // if set, the chart is not homogeneous (dimensions in it have multiple algorithms, multipliers or dividers)
+    RRDSET_FLAG_HOMOGENEOUS_CHECK                = (1 << 11), // if set, the chart should be checked to determine if the dimensions are homogeneous
+    RRDSET_FLAG_HIDDEN                           = (1 << 12), // if set, do not show this chart on the dashboard, but use it for exporting
+    RRDSET_FLAG_SYNC_CLOCK                       = (1 << 13), // if set, microseconds on next data collection will be ignored (the chart will be synced to now)
+    RRDSET_FLAG_OBSOLETE_DIMENSIONS              = (1 << 14), // this is marked by the collector/module when a chart has obsolete dimensions
+                                                              // No new values have been collected for this chart since agent start, or it was marked RRDSET_FLAG_OBSOLETE at
+                                                              // least rrdset_free_obsolete_time seconds ago.
+    RRDSET_FLAG_ARCHIVED                         = (1 << 15),
+    RRDSET_FLAG_METADATA_UPDATE                  = (1 << 16), // Mark that metadata needs to be stored
+    RRDSET_FLAG_ANOMALY_DETECTION                = (1 << 18), // flag to identify anomaly detection charts.
+    RRDSET_FLAG_INDEXED_ID                       = (1 << 19), // the rrdset is indexed by its id
+    RRDSET_FLAG_INDEXED_NAME                     = (1 << 20), // the rrdset is indexed by its name
+
+    RRDSET_FLAG_PENDING_HEALTH_INITIALIZATION    = (1 << 21),
+
+    RRDSET_FLAG_SENDER_REPLICATION_IN_PROGRESS   = (1 << 22), // the sending side has replication in progress
+    RRDSET_FLAG_SENDER_REPLICATION_FINISHED      = (1 << 23), // the sending side has completed replication
+    RRDSET_FLAG_RECEIVER_REPLICATION_IN_PROGRESS = (1 << 24), // the receiving side has replication in progress
+    RRDSET_FLAG_RECEIVER_REPLICATION_FINISHED    = (1 << 25), // the receiving side has completed replication
+
+    RRDSET_FLAG_UPSTREAM_SEND_VARIABLES          = (1 << 26), // a custom variable has been updated and needs to be exposed to parent
 } RRDSET_FLAGS;
 
 #define rrdset_flag_check(st, flag) (__atomic_load_n(&((st)->flags), __ATOMIC_SEQ_CST) & (flag))
 #define rrdset_flag_set(st, flag)   __atomic_or_fetch(&((st)->flags), flag, __ATOMIC_SEQ_CST)
-#define rrdset_flag_clear(st, flag) __atomic_and_fetch(&((st)->flags), ~flag, __ATOMIC_SEQ_CST)
+#define rrdset_flag_clear(st, flag) __atomic_and_fetch(&((st)->flags), ~(flag), __ATOMIC_SEQ_CST)
 
-struct rrdset {
-    // ------------------------------------------------------------------------
-    // binary indexing structures
+#define rrdset_is_replicating(st) (rrdset_flag_check(st, RRDSET_FLAG_SENDER_REPLICATION_IN_PROGRESS|RRDSET_FLAG_RECEIVER_REPLICATION_IN_PROGRESS) \
+    && !rrdset_flag_check(st, RRDSET_FLAG_SENDER_REPLICATION_FINISHED|RRDSET_FLAG_RECEIVER_REPLICATION_FINISHED))
 
-    avl_t avl;                                      // the index, with key the id - this has to be first!
-    avl_t avlname;                                  // the index, with key the name
+struct rrdset {
+    uuid_t chart_uuid;                             // the global UUID for this chart
 
     // ------------------------------------------------------------------------
-    // the set configuration
-
-    char id[RRD_ID_LENGTH_MAX + 1];                 // id of the data set
-
-    const char *name;                               // the name of this dimension (as presented to user)
-                                                    // this is a pointer to the config structure
-                                                    // since the config always has a higher priority
-                                                    // (the user overwrites the name of the charts)
+    // chart configuration
+
+    struct {
+        STRING *type;                               // the type of {type}.{id}
+        STRING *id;                                 // the id of {type}.{id}
+        STRING *name;                               // the name of {type}.{name}
+    } parts;
+
+    STRING *id;                                     // the unique ID of the rrdset as {type}.{id}
+    STRING *name;                                   // the unique name of the rrdset as {type}.{name}
+    STRING *family;                                 // grouping sets under the same family
+    STRING *title;                                  // title shown to user
+    STRING *units;                                  // units of measurement
+    STRING *context;                                // the template of this data set
+    STRING *plugin_name;                            // the name of the plugin that generated this
+    STRING *module_name;                            // the name of the plugin module that generated this
 
-    char *type;                                     // the type of graph RRD_TYPE_* (a category, for determining graphing options)
-    char *family;                                   // grouping sets under the same family
-    char *title;                                    // title shown to user
-    char *units;                                    // units of measurement
-
-    char *context;                                  // the template of this data set
-    uint32_t hash_context;                          // the hash of the chart's context
+    RRDSET_TYPE chart_type;                         // line, area, stacked
 
-    RRDINSTANCE_ACQUIRED *rrdinstance;              // the rrdinstance of this chart
-    RRDCONTEXT_ACQUIRED *rrdcontext;                // the rrdcontext this chart belongs to
+    long priority;                                  // the sorting priority of this chart
 
-    RRDSET_TYPE chart_type;                         // line, area, stacked
+    int update_every;                               // data collection frequency
 
-    int update_every;                               // every how many seconds is this updated?
+    DICTIONARY *rrdlabels;                          // chart labels
+    DICTIONARY *rrdsetvar_root_index;               // chart variables
+    DICTIONARY *rrddimvar_root_index;               // dimension variables
+                                                    // we use this dictionary to manage their allocation
 
-    long entries;                                   // total number of entries in the data set
+    // ------------------------------------------------------------------------
+    // operational state members
 
-    long current_entry;                             // the entry that is currently being updated
-                                                    // it goes around in a round-robin fashion
+    RRDSET_FLAGS flags;                             // flags
+    RRD_MEMORY_MODE rrd_memory_mode;                // the db mode of this rrdset
 
-    RRDSET_FLAGS flags;                             // configuration flags
-    RRDSET_FLAGS *exporting_flags;                  // array of flags for exporting connector instances
+    DICTIONARY *rrddim_root_index;                  // dimensions index
 
     int gap_when_lost_iterations_above;             // after how many lost iterations a gap should be stored
                                                     // netdata will interpolate values for gaps lower than this
+                                                    // TODO - use the global - all charts have the same value
 
-    long priority;                                  // the sorting priority of this chart
-
+    STORAGE_METRICS_GROUP *storage_metrics_groups[RRD_STORAGE_TIERS];
 
     // ------------------------------------------------------------------------
-    // members for temporary data we need for calculations
+    // linking to siblings and parents
 
-    RRD_MEMORY_MODE rrd_memory_mode;                // if set to 1, this is memory mapped
+    RRDHOST *rrdhost;                               // pointer to RRDHOST this chart belongs to
 
-    char *cache_dir;                                // the directory to store dimensions
+    RRDINSTANCE_ACQUIRED *rrdinstance;              // the rrdinstance of this chart
+    RRDCONTEXT_ACQUIRED *rrdcontext;                // the rrdcontext this chart belongs to
 
-    netdata_rwlock_t rrdset_rwlock;                 // protects dimensions linked list
+    // ------------------------------------------------------------------------
+    // data collection members
 
     size_t counter;                                 // the number of times we added values to this database
     size_t counter_done;                            // the number of times rrdset_done() has been called
 
-    union {
-        time_t last_accessed_time;                  // the last time this RRDSET has been accessed
-        time_t last_entry_t;                        // the last_entry_t computed for transient RRDSET
-    };
-    time_t upstream_resync_time;                    // the timestamp up to which we should resync clock upstream
-
-    char *plugin_name;                              // the name of the plugin that generated this
-    char *module_name;                              // the name of the plugin module that generated this
-    uuid_t *chart_uuid;                             // Store the global GUID for this chart
-                                                    // this object.
-    struct rrdset_volatile *state;                  // volatile state that is not persistently stored
-
-    size_t rrddim_page_alignment;                   // keeps metric pages in alignment when using dbengine
-
-    uint32_t hash;                                  // a simple hash on the id, to speed up searching
-                                                    // we first compare hashes, and only if the hashes are equal we do string comparisons
-
-    uint32_t hash_name;                             // a simple hash on the name
+    time_t last_accessed_time;                      // the last time this RRDSET has been accessed
 
     usec_t usec_since_last_update;                  // the time in microseconds since the last collection of data
 
     struct timeval last_updated;                    // when this data set was last updated (updated every time the rrd_stats_done() function)
     struct timeval last_collected_time;             // when did this data set last collected values
 
-    total_number collected_total;                   // used internally to calculate percentages
-    total_number last_collected_total;              // used internally to calculate percentages
-
-    RRDFAMILY *rrdfamily;                           // pointer to RRDFAMILY this chart belongs to
-    RRDHOST *rrdhost;                               // pointer to RRDHOST this chart belongs to
+    size_t rrdlabels_last_saved_version;
 
-    struct rrdset *next;                            // linking of rrdsets
+    DICTIONARY *functions_view;                     // collector functions this rrdset supports, can be NULL
 
     // ------------------------------------------------------------------------
-    // local variables
+    // data collection - streaming to parents, temp variables
 
-    NETDATA_DOUBLE green;                        // green threshold for this chart
-    NETDATA_DOUBLE red;                          // red threshold for this chart
-
-    avl_tree_lock rrdvar_root_index;                // RRDVAR index for this chart
-    RRDSETVAR *variables;                           // RRDSETVAR linked list for this chart (one RRDSETVAR, many RRDVARs)
-    RRDCALC *alarms;                                // RRDCALC linked list for this chart
+    time_t upstream_resync_time;                    // the timestamp up to which we should resync clock upstream
 
     // ------------------------------------------------------------------------
-    // members for checking the data when loading from disk
+    // db mode SAVE, MAP specifics
+    // TODO - they should be managed by storage engine
+    //        (RRDSET_DB_STATE ptr to an undefined structure, and a call to clean this up during destruction)
 
+    char *cache_dir;                                // the directory to store dimensions
     unsigned long memsize;                          // how much mem we have allocated for this (without dimensions)
     void *st_on_file;                               // compatibility with V019 RRDSET files
 
     // ------------------------------------------------------------------------
-    // the dimensions
+    // db mode RAM, SAVE, MAP, ALLOC, NONE specifics
+    // TODO - they should be managed by storage engine
+    //        (RRDSET_DB_STATE ptr to an undefined structure, and a call to clean this up during destruction)
 
-    avl_tree_lock dimensions_index;                 // the root of the dimensions index
-    RRDDIM *dimensions;                             // the actual data for every dimension
+    long entries;                                   // total number of entries in the data set
+
+    long current_entry;                             // the entry that is currently being updated
+                                                    // it goes around in a round-robin fashion
+
+    // ------------------------------------------------------------------------
+    // exporting to 3rd party time-series members
+    // TODO - they should be managed by exporting engine
+    //        (RRDSET_EXPORTING_STATE ptr to an undefined structure, and a call to clean this up during destruction)
+
+    RRDSET_FLAGS *exporting_flags;                  // array of flags for exporting connector instances
+
+    // ------------------------------------------------------------------------
+    // health monitoring members
+    // TODO - they should be managed by health
+    //        (RRDSET_HEALTH_STATE ptr to an undefined structure, and a call to clean this up during destruction)
+
+    NETDATA_DOUBLE green;                           // green threshold for this chart
+    NETDATA_DOUBLE red;                             // red threshold for this chart
+
+    DICTIONARY *rrdvars;                            // RRDVAR index for this chart
+    const RRDFAMILY_ACQUIRED *rrdfamily;            // pointer to RRDFAMILY dictionary item, this chart belongs to
+
+    struct {
+        netdata_rwlock_t rwlock;                    // protection for RRDCALC *base
+        RRDCALC *base;                              // double linked list of RRDCALC related to this RRDSET
+    } alerts;
+
+#ifdef NETDATA_LOG_REPLICATION_REQUESTS
+    struct {
+        bool log_next_data_collection;
+        bool start_streaming;
+        time_t after;
+        time_t before;
+    } replay;
+#endif // NETDATA_LOG_REPLICATION_REQUESTS
 };
 
-#define rrdset_rdlock(st) netdata_rwlock_rdlock(&((st)->rrdset_rwlock))
-#define rrdset_wrlock(st) netdata_rwlock_wrlock(&((st)->rrdset_rwlock))
-#define rrdset_unlock(st) netdata_rwlock_unlock(&((st)->rrdset_rwlock))
+#define rrdset_plugin_name(st) string2str((st)->plugin_name)
+#define rrdset_module_name(st) string2str((st)->module_name)
+#define rrdset_units(st) string2str((st)->units)
+#define rrdset_parts_type(st) string2str((st)->parts.type)
+#define rrdset_family(st) string2str((st)->family)
+#define rrdset_title(st) string2str((st)->title)
+#define rrdset_context(st) string2str((st)->context)
+#define rrdset_name(st) string2str((st)->name)
+#define rrdset_id(st) string2str((st)->id)
 
+STRING *rrd_string_strdupz(const char *s);
 
 // ----------------------------------------------------------------------------
 // these loop macros make sure the linked list is accessed with the right lock
 
 #define rrdset_foreach_read(st, host) \
-    for((st) = (host)->rrdset_root, rrdhost_check_rdlock(host); st ; (st) = (st)->next)
+    dfe_start_read((host)->rrdset_root_index, st)
 
 #define rrdset_foreach_write(st, host) \
-    for((st) = (host)->rrdset_root, rrdhost_check_wrlock(host); st ; (st) = (st)->next)
+    dfe_start_write((host)->rrdset_root_index, st)
+
+#define rrdset_foreach_reentrant(st, host) \
+    dfe_start_reentrant((host)->rrdset_root_index, st)
+
+#define rrdset_foreach_done(st) \
+    dfe_done(st)
 
+#define rrdset_number_of_dimensions(st) \
+    dictionary_entries((st)->rrddim_root_index)
 
-extern void rrdset_memory_file_save(RRDSET *st);
-extern void rrdset_memory_file_free(RRDSET *st);
-extern void rrdset_memory_file_update(RRDSET *st);
-extern const char *rrdset_cache_filename(RRDSET *st);
-extern bool rrdset_memory_load_or_create_map_save(RRDSET *st_on_file, RRD_MEMORY_MODE memory_mode);
+void rrdset_memory_file_save(RRDSET *st);
+void rrdset_memory_file_free(RRDSET *st);
+void rrdset_memory_file_update(RRDSET *st);
+const char *rrdset_cache_filename(RRDSET *st);
+bool rrdset_memory_load_or_create_map_save(RRDSET *st_on_file, RRD_MEMORY_MODE memory_mode);
+
+#include "rrdfunctions.h"
 
 // ----------------------------------------------------------------------------
 // RRDHOST flags
@@ -652,30 +736,70 @@ extern bool rrdset_memory_load_or_create_map_save(RRDSET *st_on_file, RRD_MEMORY
 // and may lead to missing information.
 
 typedef enum rrdhost_flags {
-    RRDHOST_FLAG_ORPHAN                 = (1 << 0), // this host is orphan (not receiving data)
-    RRDHOST_FLAG_DELETE_OBSOLETE_CHARTS = (1 << 1), // delete files of obsolete charts
-    RRDHOST_FLAG_DELETE_ORPHAN_HOST     = (1 << 2), // delete the entire host when orphan
-    RRDHOST_FLAG_EXPORTING_SEND         = (1 << 3), // send it to external databases
-    RRDHOST_FLAG_EXPORTING_DONT_SEND    = (1 << 4), // don't send it to external databases
-    RRDHOST_FLAG_ARCHIVED               = (1 << 5), // The host is archived, no collected charts yet
-    RRDHOST_FLAG_MULTIHOST              = (1 << 6), // Host belongs to localhost/megadb
-    RRDHOST_FLAG_PENDING_FOREACH_ALARMS = (1 << 7), // contains dims with uninitialized foreach alarms
-    RRDHOST_FLAG_STREAM_LABELS_UPDATE   = (1 << 8),
-    RRDHOST_FLAG_STREAM_LABELS_STOP     = (1 << 9),
-    RRDHOST_FLAG_ACLK_STREAM_CONTEXTS   = (1 << 10), // when set, we should send ACLK stream context updates
+    // Orphan, Archived and Obsolete flags
+    RRDHOST_FLAG_ORPHAN                         = (1 << 10), // this host is orphan (not receiving data)
+    RRDHOST_FLAG_ARCHIVED                       = (1 << 11), // The host is archived, no collected charts yet
+    RRDHOST_FLAG_PENDING_OBSOLETE_CHARTS        = (1 << 12), // the host has pending chart obsoletions
+    RRDHOST_FLAG_PENDING_OBSOLETE_DIMENSIONS    = (1 << 13), // the host has pending dimension obsoletions
+
+    // Streaming sender
+    RRDHOST_FLAG_RRDPUSH_SENDER_INITIALIZED     = (1 << 14), // the host has initialized rrdpush structures
+    RRDHOST_FLAG_RRDPUSH_SENDER_SPAWN           = (1 << 15), // When set, the sender thread is running
+    RRDHOST_FLAG_RRDPUSH_SENDER_CONNECTED       = (1 << 16), // When set, the host is connected to a parent
+    RRDHOST_FLAG_RRDPUSH_SENDER_READY_4_METRICS = (1 << 17), // when set, rrdset_done() should push metrics to parent
+    RRDHOST_FLAG_RRDPUSH_SENDER_LOGGED_STATUS   = (1 << 18), // when set, we have logged the status of metrics streaming
+    RRDHOST_FLAG_RRDPUSH_SENDER_JOIN            = (1 << 19), // When set, we want to join the sender thread
+
+    // Health
+    RRDHOST_FLAG_PENDING_HEALTH_INITIALIZATION  = (1 << 20), // contains charts and dims with uninitialized variables
+    RRDHOST_FLAG_INITIALIZED_HEALTH             = (1 << 21), // the host has initialized health structures
+
+    // Exporting
+    RRDHOST_FLAG_EXPORTING_SEND                 = (1 << 22), // send it to external databases
+    RRDHOST_FLAG_EXPORTING_DONT_SEND            = (1 << 23), // don't send it to external databases
+
+    // ACLK
+    RRDHOST_FLAG_ACLK_STREAM_CONTEXTS           = (1 << 24), // when set, we should send ACLK stream context updates
+    // Metadata
+    RRDHOST_FLAG_METADATA_UPDATE                = (1 << 25), // metadata needs to be stored in the database
+
+    RRDHOST_FLAG_RRDPUSH_RECEIVER_DISCONNECTED = ( 1 << 26), // set when the receiver part is disconnected
 } RRDHOST_FLAGS;
 
 #define rrdhost_flag_check(host, flag) (__atomic_load_n(&((host)->flags), __ATOMIC_SEQ_CST) & (flag))
 #define rrdhost_flag_set(host, flag)   __atomic_or_fetch(&((host)->flags), flag, __ATOMIC_SEQ_CST)
-#define rrdhost_flag_clear(host, flag) __atomic_and_fetch(&((host)->flags), ~flag, __ATOMIC_SEQ_CST)
+#define rrdhost_flag_clear(host, flag) __atomic_and_fetch(&((host)->flags), ~(flag), __ATOMIC_SEQ_CST)
 
 #ifdef NETDATA_INTERNAL_CHECKS
 #define rrdset_debug(st, fmt, args...) do { if(unlikely(debug_flags & D_RRD_STATS && rrdset_flag_check(st, RRDSET_FLAG_DEBUG))) \
-            debug_int(__FILE__, __FUNCTION__, __LINE__, "%s: " fmt, st->name, ##args); } while(0)
+            debug_int(__FILE__, __FUNCTION__, __LINE__, "%s: " fmt, rrdset_name(st), ##args); } while(0)
 #else
 #define rrdset_debug(st, fmt, args...) debug_dummy()
 #endif
 
+typedef enum {
+    // Indexing
+    RRDHOST_OPTION_INDEXED_MACHINE_GUID     = (1 << 0), // when set, we have indexed its machine guid
+    RRDHOST_OPTION_INDEXED_HOSTNAME         = (1 << 1), // when set, we have indexed its hostname
+
+    // Streaming configuration
+    RRDHOST_OPTION_SENDER_ENABLED           = (1 << 2), // set when the host is configured to send metrics to a parent
+
+    // Configuration options
+    RRDHOST_OPTION_DELETE_OBSOLETE_CHARTS   = (1 << 3), // delete files of obsolete charts
+    RRDHOST_OPTION_DELETE_ORPHAN_HOST       = (1 << 4), // delete the entire host when orphan
+
+    RRDHOST_OPTION_REPLICATION              = (1 << 5), // when set, we support replication for this host
+} RRDHOST_OPTIONS;
+
+#define rrdhost_option_check(host, flag) ((host)->options & (flag))
+#define rrdhost_option_set(host, flag)   (host)->options |= flag
+#define rrdhost_option_clear(host, flag) (host)->options &= ~(flag)
+
+#define rrdhost_has_rrdpush_sender_enabled(host) (rrdhost_option_check(host, RRDHOST_OPTION_SENDER_ENABLED) && (host)->sender)
+
+#define rrdhost_can_send_definitions_to_parent(host) (rrdhost_has_rrdpush_sender_enabled(host) && rrdhost_flag_check(host, RRDHOST_FLAG_RRDPUSH_SENDER_CONNECTED))
+
 // ----------------------------------------------------------------------------
 // Health data
 
@@ -689,34 +813,30 @@ struct alarm_entry {
     time_t duration;
     time_t non_clear_duration;
 
-    char *name;
-    uint32_t hash_name;
-
-    char *chart;
-    uint32_t hash_chart;
-    char *chart_context;
+    STRING *name;
+    STRING *chart;
+    STRING *chart_context;
+    STRING *family;
 
-    char *family;
+    STRING *classification;
+    STRING *component;
+    STRING *type;
 
-    char *classification;
-    char *component;
-    char *type;
-
-    char *exec;
-    char *recipient;
+    STRING *exec;
+    STRING *recipient;
     time_t exec_run_timestamp;
     int exec_code;
     uint64_t exec_spawn_serial;
 
-    char *source;
-    char *units;
-    char *info;
+    STRING *source;
+    STRING *units;
+    STRING *info;
 
     NETDATA_DOUBLE old_value;
     NETDATA_DOUBLE new_value;
 
-    char *old_value_string;
-    char *new_value_string;
+    STRING *old_value_string;
+    STRING *new_value_string;
 
     RRDCALC_STATUS old_status;
     RRDCALC_STATUS new_status;
@@ -736,6 +856,20 @@ struct alarm_entry {
     struct alarm_entry *prev_in_progress;
 };
 
+#define ae_name(ae) string2str((ae)->name)
+#define ae_chart_name(ae) string2str((ae)->chart)
+#define ae_chart_context(ae) string2str((ae)->chart_context)
+#define ae_family(ae) string2str((ae)->family)
+#define ae_classification(ae) string2str((ae)->classification)
+#define ae_component(ae) string2str((ae)->component)
+#define ae_type(ae) string2str((ae)->type)
+#define ae_exec(ae) string2str((ae)->exec)
+#define ae_recipient(ae) string2str((ae)->recipient)
+#define ae_source(ae) string2str((ae)->source)
+#define ae_units(ae) string2str((ae)->units)
+#define ae_info(ae) string2str((ae)->info)
+#define ae_old_value_string(ae) string2str((ae)->old_value_string)
+#define ae_new_value_string(ae) string2str((ae)->new_value_string)
 
 typedef struct alarm_log {
     uint32_t next_log_id;
@@ -789,79 +923,71 @@ struct rrdhost_system_info {
 };
 
 struct rrdhost {
-    avl_t avl;                                      // the index of hosts
+    char machine_guid[GUID_LEN + 1];                // the unique ID of this host
 
     // ------------------------------------------------------------------------
     // host information
 
-    char *hostname;                                 // the hostname of this host
-    uint32_t hash_hostname;                         // the hostname hash
+    STRING *hostname;                               // the hostname of this host
+    STRING *registry_hostname;                      // the registry hostname for this host
+    STRING *os;                                     // the O/S type of the host
+    STRING *tags;                                   // tags for this host
+    STRING *timezone;                               // the timezone of the host
+    STRING *abbrev_timezone;                        // the abbriviated timezone of the host
+    STRING *program_name;                           // the program name that collects metrics for this host
+    STRING *program_version;                        // the program version that collects metrics for this host
 
-    char *registry_hostname;                        // the registry hostname for this host
-
-    char machine_guid[GUID_LEN + 1];                // the unique ID of this host
-    uint32_t hash_machine_guid;                     // the hash of the unique ID
-
-    const char *os;                                 // the O/S type of the host
-    const char *tags;                               // tags for this host
-    const char *timezone;                           // the timezone of the host
-
-    const char *abbrev_timezone;                    // the abbriviated timezone of the host
     int32_t utc_offset;                             // the offset in seconds from utc
 
-    RRDHOST_FLAGS flags;                            // flags about this RRDHOST
+    RRDHOST_OPTIONS options;                        // configuration option for this RRDHOST (no atomics on this)
+    RRDHOST_FLAGS flags;                            // runtime flags about this RRDHOST (atomics on this)
     RRDHOST_FLAGS *exporting_flags;                 // array of flags for exporting connector instances
 
     int rrd_update_every;                           // the update frequency of the host
     long rrd_history_entries;                       // the number of history entries for the host's charts
-    RRD_MEMORY_MODE rrd_memory_mode;                // the memory more for the charts of this host
+
+    RRD_MEMORY_MODE rrd_memory_mode;                // the configured memory more for the charts of this host
+                                                    // the actual per tier is at .db[tier].mode
 
     char *cache_dir;                                // the directory to save RRD cache files
     char *varlib_dir;                               // the directory to save health log
 
-    char *program_name;                             // the program name that collects metrics for this host
-    char *program_version;                          // the program version that collects metrics for this host
+    struct {
+        RRD_MEMORY_MODE mode;                       // the db mode for this tier
+        STORAGE_ENGINE *eng;                        // the storage engine API for this tier
+        STORAGE_INSTANCE *instance;                 // the db instance for this tier
+        size_t tier_grouping;                       // tier 0 iterations aggregated on this tier
+    } db[RRD_STORAGE_TIERS];
 
     struct rrdhost_system_info *system_info;        // information collected from the host environment
 
     // ------------------------------------------------------------------------
-    // streaming of data to remote hosts - rrdpush
+    // streaming of data to remote hosts - rrdpush sender
 
-    unsigned int rrdpush_send_enabled;            // 1 when this host sends metrics to another netdata
     char *rrdpush_send_destination;                 // where to send metrics to
     char *rrdpush_send_api_key;                     // the api key at the receiving netdata
     struct rrdpush_destinations *destinations;      // a linked list of possible destinations
     struct rrdpush_destinations *destination;       // the current destination from the above list
+    SIMPLE_PATTERN *rrdpush_send_charts_matching;   // pattern to match the charts to be sent
+
+    time_t rrdpush_seconds_to_replicate;            // max time we want to replicate from the child
+    time_t rrdpush_replication_step;                // seconds per replication step
+    size_t rrdpush_receiver_replicating_charts;     // the number of charts currently being replicated from a child
 
     // the following are state information for the threading
     // streaming metrics from this netdata to an upstream netdata
     struct sender_state *sender;
-    volatile unsigned int rrdpush_sender_spawn;   // 1 when the sender thread has been spawn
     netdata_thread_t rrdpush_sender_thread;         // the sender thread
+    size_t rrdpush_sender_replicating_charts;       // the number of charts currently being replicated to a parent
     void *dbsync_worker;
 
-    bool rrdpush_sender_connected;                  // 1 when the sender is ready to push metrics
-    int rrdpush_sender_socket;                      // the fd of the socket to the remote host, or -1
-
-    volatile unsigned int rrdpush_sender_error_shown; // 1 when we have logged a communication error
-    volatile unsigned int rrdpush_sender_join;    // 1 when we have to join the sending thread
-
-    SIMPLE_PATTERN *rrdpush_send_charts_matching;   // pattern to match the charts to be sent
-
-    int rrdpush_sender_pipe[2];                     // collector to sender thread signaling
-    //BUFFER *rrdpush_sender_buffer;                  // collector fills it, sender sends it
-
-    //uint32_t stream_version;                             //Set the current version of the stream.
-
     // ------------------------------------------------------------------------
-    // streaming of data from remote hosts - rrdpush
-
-    volatile size_t connected_senders;              // when remote hosts are streaming to this
-                                                    // host, this is the counter of connected clients
+    // streaming of data from remote hosts - rrdpush receiver
 
     time_t senders_connect_time;                    // the time the last sender was connected
     time_t senders_last_chart_command;              // the time of the last CHART streaming command
     time_t senders_disconnected_time;               // the time the last sender was disconnected
+    int senders_count;                              // number of senders currently streaming
 
     struct receiver_state *receiver;
     netdata_mutex_t receiver_lock;
@@ -871,45 +997,30 @@ struct rrdhost {
     // ------------------------------------------------------------------------
     // health monitoring options
 
-    unsigned int health_enabled;                  // 1 when this host has health enabled
-    time_t health_delay_up_to;                      // a timestamp to delay alarms processing up to
-    char *health_default_exec;                      // the full path of the alarms notifications program
-    char *health_default_recipient;                 // the default recipient for all alarms
-    char *health_log_filename;                      // the alarms event log filename
-    size_t health_log_entries_written;              // the number of alarm events written to the alarms event log
-    FILE *health_log_fp;                            // the FILE pointer to the open alarms event log file
-    uint32_t health_default_warn_repeat_every;      // the default value for the interval between repeating warning notifications
-    uint32_t health_default_crit_repeat_every;      // the default value for the interval between repeating critical notifications
-
+    unsigned int health_enabled;                   // 1 when this host has health enabled
+    bool health_spawn;                             // true when health thread is running
+    netdata_thread_t health_thread;                // the health thread
+    unsigned int aclk_alert_reloaded;              // 1 on thread start and health reload, 0 after removed are sent
+    time_t health_delay_up_to;                     // a timestamp to delay alarms processing up to
+    STRING *health_default_exec;                   // the full path of the alarms notifications program
+    STRING *health_default_recipient;              // the default recipient for all alarms
+    char *health_log_filename;                     // the alarms event log filename
+    size_t health_log_entries_written;             // the number of alarm events written to the alarms event log
+    FILE *health_log_fp;                           // the FILE pointer to the open alarms event log file
+    uint32_t health_default_warn_repeat_every;     // the default value for the interval between repeating warning notifications
+    uint32_t health_default_crit_repeat_every;     // the default value for the interval between repeating critical notifications
 
     // all RRDCALCs are primarily allocated and linked here
-    // RRDCALCs may be linked to charts at any point
-    // (charts may or may not exist when these are loaded)
-    RRDCALC *alarms;
-    RRDCALC *alarms_with_foreach;
-    avl_tree_lock alarms_idx_health_log;
-    avl_tree_lock alarms_idx_name;
+    DICTIONARY *rrdcalc_root_index;
+
+    // templates of alarms
+    DICTIONARY *rrdcalctemplate_root_index;
 
     ALARM_LOG health_log;                           // alarms historical events (event log)
     uint32_t health_last_processed_id;              // the last processed health id from the log
     uint32_t health_max_unique_id;                  // the max alarm log unique id given for the host
     uint32_t health_max_alarm_id;                   // the max alarm id given for the host
 
-    // templates of alarms
-    // these are used to create alarms when charts
-    // are created or renamed, that match them
-    RRDCALCTEMPLATE *templates;
-    RRDCALCTEMPLATE *alarms_template_with_foreach;
-
-
-    // ------------------------------------------------------------------------
-    // the charts of the host
-
-    RRDSET *rrdset_root;                            // the host charts
-
-    unsigned int obsolete_charts_count;
-
-
     // ------------------------------------------------------------------------
     // locks
 
@@ -921,37 +1032,46 @@ struct rrdhost {
 
     // ------------------------------------------------------------------------
     // Support for host-level labels
-    DICTIONARY *host_labels;
+    DICTIONARY *rrdlabels;
 
     // ------------------------------------------------------------------------
-    // indexes
+    // Support for functions
+    DICTIONARY *functions;                          // collector functions this rrdset supports, can be NULL
 
-    avl_tree_lock rrdset_root_index;                // the host's charts index (by id)
-    avl_tree_lock rrdset_root_index_name;           // the host's charts index (by name)
+    // ------------------------------------------------------------------------
+    // indexes
 
-    avl_tree_lock rrdfamily_root_index;             // the host's chart families index
-    avl_tree_lock rrdvar_root_index;                // the host's chart variables index
+    DICTIONARY *rrdset_root_index;                  // the host's charts index (by id)
+    DICTIONARY *rrdset_root_index_name;             // the host's charts index (by name)
 
-    STORAGE_INSTANCE *storage_instance[RRD_STORAGE_TIERS];  // the database instances of the storage tiers
+    DICTIONARY *rrdfamily_root_index;               // the host's chart families index
+    DICTIONARY *rrdvars;                            // the host's chart variables index
+                                                    // this includes custom host variables
 
-    RRDCONTEXTS *rrdctx_queue;
+    RRDCONTEXTS *rrdctx_hub_queue;
+    RRDCONTEXTS *rrdctx_post_processing_queue;
     RRDCONTEXTS *rrdctx;
 
     uuid_t  host_uuid;                              // Global GUID for this host
     uuid_t  *node_id;                               // Cloud node_id
 
-#ifdef ENABLE_HTTPS
-    struct netdata_ssl ssl;                         //Structure used to encrypt the connection
-    struct netdata_ssl stream_ssl;                         //Structure used to encrypt the stream
-#endif
-
     netdata_mutex_t aclk_state_lock;
     aclk_rrdhost_state aclk_state;
 
     struct rrdhost *next;
+    struct rrdhost *prev;
 };
 extern RRDHOST *localhost;
 
+#define rrdhost_hostname(host) string2str((host)->hostname)
+#define rrdhost_registry_hostname(host) string2str((host)->registry_hostname)
+#define rrdhost_os(host) string2str((host)->os)
+#define rrdhost_tags(host) string2str((host)->tags)
+#define rrdhost_timezone(host) string2str((host)->timezone)
+#define rrdhost_abbrev_timezone(host) string2str((host)->abbrev_timezone)
+#define rrdhost_program_name(host) string2str((host)->program_name)
+#define rrdhost_program_version(host) string2str((host)->program_version)
+
 #define rrdhost_rdlock(host) netdata_rwlock_rdlock(&((host)->rrdhost_rwlock))
 #define rrdhost_wrlock(host) netdata_rwlock_wrlock(&((host)->rrdhost_rwlock))
 #define rrdhost_unlock(host) netdata_rwlock_unlock(&((host)->rrdhost_rwlock))
@@ -959,6 +1079,19 @@ extern RRDHOST *localhost;
 #define rrdhost_aclk_state_lock(host) netdata_mutex_lock(&((host)->aclk_state_lock))
 #define rrdhost_aclk_state_unlock(host) netdata_mutex_unlock(&((host)->aclk_state_lock))
 
+#define rrdhost_receiver_replicating_charts(host) (__atomic_load_n(&((host)->rrdpush_receiver_replicating_charts), __ATOMIC_RELAXED))
+#define rrdhost_receiver_replicating_charts_plus_one(host) (__atomic_add_fetch(&((host)->rrdpush_receiver_replicating_charts), 1, __ATOMIC_RELAXED))
+#define rrdhost_receiver_replicating_charts_minus_one(host) (__atomic_sub_fetch(&((host)->rrdpush_receiver_replicating_charts), 1, __ATOMIC_RELAXED))
+#define rrdhost_receiver_replicating_charts_zero(host) (__atomic_store_n(&((host)->rrdpush_receiver_replicating_charts), 0, __ATOMIC_RELAXED))
+
+#define rrdhost_sender_replicating_charts(host) (__atomic_load_n(&((host)->rrdpush_sender_replicating_charts), __ATOMIC_RELAXED))
+#define rrdhost_sender_replicating_charts_plus_one(host) (__atomic_add_fetch(&((host)->rrdpush_sender_replicating_charts), 1, __ATOMIC_RELAXED))
+#define rrdhost_sender_replicating_charts_minus_one(host) (__atomic_sub_fetch(&((host)->rrdpush_sender_replicating_charts), 1, __ATOMIC_RELAXED))
+#define rrdhost_sender_replicating_charts_zero(host) (__atomic_store_n(&((host)->rrdpush_sender_replicating_charts), 0, __ATOMIC_RELAXED))
+
+extern DICTIONARY *rrdhost_root_index;
+long rrdhost_hosts_available(void);
+
 // ----------------------------------------------------------------------------
 // these loop macros make sure the linked list is accessed with the right lock
 
@@ -980,19 +1113,24 @@ extern netdata_rwlock_t rrd_rwlock;
 
 // ----------------------------------------------------------------------------
 
-extern bool is_storage_engine_shared(STORAGE_INSTANCE *engine);
+bool is_storage_engine_shared(STORAGE_INSTANCE *engine);
+void rrdset_index_init(RRDHOST *host);
+void rrdset_index_destroy(RRDHOST *host);
+
+void rrddim_index_init(RRDSET *st);
+void rrddim_index_destroy(RRDSET *st);
 
 // ----------------------------------------------------------------------------
 
 extern size_t rrd_hosts_available;
 extern time_t rrdhost_free_orphan_time;
 
-extern int rrd_init(char *hostname, struct rrdhost_system_info *system_info);
+int rrd_init(char *hostname, struct rrdhost_system_info *system_info);
 
-extern RRDHOST *rrdhost_find_by_hostname(const char *hostname, uint32_t hash);
-extern RRDHOST *rrdhost_find_by_guid(const char *guid, uint32_t hash);
+RRDHOST *rrdhost_find_by_hostname(const char *hostname);
+RRDHOST *rrdhost_find_by_guid(const char *guid);
 
-extern RRDHOST *rrdhost_find_or_create(
+RRDHOST *rrdhost_find_or_create(
         const char *hostname
         , const char *registry_hostname
         , const char *guid
@@ -1011,11 +1149,14 @@ extern RRDHOST *rrdhost_find_or_create(
         , char *rrdpush_destination
         , char *rrdpush_api_key
         , char *rrdpush_send_charts_matching
+        , bool rrdpush_enable_replication
+        , time_t rrdpush_seconds_to_replicate
+        , time_t rrdpush_replication_step
         , struct rrdhost_system_info *system_info
         , bool is_archived
 );
 
-extern void rrdhost_update(RRDHOST *host
+void rrdhost_update(RRDHOST *host
     , const char *hostname
     , const char *registry_hostname
     , const char *guid
@@ -1034,18 +1175,21 @@ extern void rrdhost_update(RRDHOST *host
     , char *rrdpush_destination
     , char *rrdpush_api_key
     , char *rrdpush_send_charts_matching
+    , bool rrdpush_enable_replication
+    , time_t rrdpush_seconds_to_replicate
+    , time_t rrdpush_replication_step
     , struct rrdhost_system_info *system_info
 );
 
-extern int rrdhost_set_system_info_variable(struct rrdhost_system_info *system_info, char *name, char *value);
+int rrdhost_set_system_info_variable(struct rrdhost_system_info *system_info, char *name, char *value);
 
 #if defined(NETDATA_INTERNAL_CHECKS) && defined(NETDATA_VERIFY_LOCKS)
-extern void __rrdhost_check_wrlock(RRDHOST *host, const char *file, const char *function, const unsigned long line);
-extern void __rrdhost_check_rdlock(RRDHOST *host, const char *file, const char *function, const unsigned long line);
-extern void __rrdset_check_rdlock(RRDSET *st, const char *file, const char *function, const unsigned long line);
-extern void __rrdset_check_wrlock(RRDSET *st, const char *file, const char *function, const unsigned long line);
-extern void __rrd_check_rdlock(const char *file, const char *function, const unsigned long line);
-extern void __rrd_check_wrlock(const char *file, const char *function, const unsigned long line);
+void __rrdhost_check_wrlock(RRDHOST *host, const char *file, const char *function, const unsigned long line);
+void __rrdhost_check_rdlock(RRDHOST *host, const char *file, const char *function, const unsigned long line);
+void __rrdset_check_rdlock(RRDSET *st, const char *file, const char *function, const unsigned long line);
+void __rrdset_check_wrlock(RRDSET *st, const char *file, const char *function, const unsigned long line);
+void __rrd_check_rdlock(const char *file, const char *function, const unsigned long line);
+void __rrd_check_wrlock(const char *file, const char *function, const unsigned long line);
 
 #define rrdhost_check_rdlock(host) __rrdhost_check_rdlock(host, __FILE__, __FUNCTION__, __LINE__)
 #define rrdhost_check_wrlock(host) __rrdhost_check_wrlock(host, __FILE__, __FUNCTION__, __LINE__)
@@ -1066,9 +1210,9 @@ extern void __rrd_check_wrlock(const char *file, const char *function, const uns
 // ----------------------------------------------------------------------------
 // RRDSET functions
 
-extern int rrdset_set_name(RRDSET *st, const char *name);
+int rrdset_reset_name(RRDSET *st, const char *name);
 
-extern RRDSET *rrdset_create_custom(RRDHOST *host
+RRDSET *rrdset_create_custom(RRDHOST *host
                              , const char *type
                              , const char *id
                              , const char *name
@@ -1090,22 +1234,22 @@ extern RRDSET *rrdset_create_custom(RRDHOST *host
 #define rrdset_create_localhost(type, id, name, family, context, title, units, plugin, module, priority, update_every, chart_type) \
     rrdset_create(localhost, type, id, name, family, context, title, units, plugin, module, priority, update_every, chart_type)
 
-extern void rrdhost_free_all(void);
-extern void rrdhost_save_all(void);
-extern void rrdhost_cleanup_all(void);
+void rrdhost_free_all(void);
+void rrdhost_save_all(void);
+void rrdhost_cleanup_all(void);
 
-extern void rrdhost_cleanup_orphan_hosts_nolock(RRDHOST *protected_host);
-extern void rrdhost_system_info_free(struct rrdhost_system_info *system_info);
-extern void rrdhost_free(RRDHOST *host, bool force);
-extern void rrdhost_save_charts(RRDHOST *host);
-extern void rrdhost_delete_charts(RRDHOST *host);
-extern void rrd_cleanup_obsolete_charts();
+void rrdhost_system_info_free(struct rrdhost_system_info *system_info);
+void rrdhost_free(RRDHOST *host, bool force);
+void rrdhost_save_charts(RRDHOST *host);
+void rrdhost_delete_charts(RRDHOST *host);
 
-extern int rrdhost_should_be_removed(RRDHOST *host, RRDHOST *protected_host, time_t now);
+int rrdhost_should_be_removed(RRDHOST *host, RRDHOST *protected_host, time_t now);
 
-extern void rrdset_update_heterogeneous_flag(RRDSET *st);
+void rrdset_update_heterogeneous_flag(RRDSET *st);
 
-extern RRDSET *rrdset_find(RRDHOST *host, const char *id);
+time_t rrdset_set_update_every(RRDSET *st, time_t update_every);
+
+RRDSET *rrdset_find(RRDHOST *host, const char *id);
 #define rrdset_find_localhost(id) rrdset_find(localhost, id)
 /* This will not return charts that are archived */
 static inline RRDSET *rrdset_find_active_localhost(const char *id)
@@ -1116,7 +1260,7 @@ static inline RRDSET *rrdset_find_active_localhost(const char *id)
     return st;
 }
 
-extern RRDSET *rrdset_find_bytype(RRDHOST *host, const char *type, const char *id);
+RRDSET *rrdset_find_bytype(RRDHOST *host, const char *type, const char *id);
 #define rrdset_find_bytype_localhost(type, id) rrdset_find_bytype(localhost, type, id)
 /* This will not return charts that are archived */
 static inline RRDSET *rrdset_find_active_bytype_localhost(const char *type, const char *id)
@@ -1127,7 +1271,7 @@ static inline RRDSET *rrdset_find_active_bytype_localhost(const char *type, cons
     return st;
 }
 
-extern RRDSET *rrdset_find_byname(RRDHOST *host, const char *name);
+RRDSET *rrdset_find_byname(RRDHOST *host, const char *name);
 #define rrdset_find_byname_localhost(name)  rrdset_find_byname(localhost, name)
 /* This will not return charts that are archived */
 static inline RRDSET *rrdset_find_active_byname_localhost(const char *name)
@@ -1138,190 +1282,115 @@ static inline RRDSET *rrdset_find_active_byname_localhost(const char *name)
     return st;
 }
 
-extern void rrdset_next_usec_unfiltered(RRDSET *st, usec_t microseconds);
-extern void rrdset_next_usec(RRDSET *st, usec_t microseconds);
+void rrdset_next_usec_unfiltered(RRDSET *st, usec_t microseconds);
+void rrdset_next_usec(RRDSET *st, usec_t microseconds);
+void rrdset_timed_next(RRDSET *st, struct timeval now, usec_t microseconds);
 #define rrdset_next(st) rrdset_next_usec(st, 0ULL)
 
-extern void rrdset_done(RRDSET *st);
+void rrdset_timed_done(RRDSET *st, struct timeval now, bool pending_rrdset_next);
+void rrdset_done(RRDSET *st);
 
-extern void rrdset_is_obsolete(RRDSET *st);
-extern void rrdset_isnot_obsolete(RRDSET *st);
+void rrdset_is_obsolete(RRDSET *st);
+void rrdset_isnot_obsolete(RRDSET *st);
 
 // checks if the RRDSET should be offered to viewers
-#define rrdset_is_available_for_viewers(st) (!rrdset_flag_check(st, RRDSET_FLAG_HIDDEN) && !rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE) && !rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED) && (st)->dimensions && (st)->rrd_memory_mode != RRD_MEMORY_MODE_NONE)
-#define rrdset_is_available_for_exporting_and_alarms(st) (!rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE) && !rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED) && (st)->dimensions)
-#define rrdset_is_archived(st) (rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED) && (st)->dimensions)
-
-// get the timestamp of the last entry in the round robin database
-static inline time_t rrddim_last_entry_t(RRDDIM *rd) {
-    time_t latest = rd->tiers[0]->query_ops.latest_time(rd->tiers[0]->db_metric_handle);
-
-    for(int tier = 1; tier < storage_tiers ;tier++) {
-        if(unlikely(!rd->tiers[tier])) continue;
-
-        time_t t = rd->tiers[tier]->query_ops.latest_time(rd->tiers[tier]->db_metric_handle);
-        if(t > latest)
-            latest = t;
-    }
-
-    return latest;
-}
-
-static inline time_t rrddim_first_entry_t(RRDDIM *rd) {
-    time_t oldest = 0;
-
-    for(int tier = 0; tier < storage_tiers ;tier++) {
-        if(unlikely(!rd->tiers[tier])) continue;
-
-        time_t t = rd->tiers[tier]->query_ops.oldest_time(rd->tiers[tier]->db_metric_handle);
-        if(t != 0 && (oldest == 0 || t < oldest))
-            oldest = t;
-    }
-
-    return oldest;
-}
-
-// get the timestamp of the last entry in the round robin database
-static inline time_t rrdset_last_entry_t_nolock(RRDSET *st) {
-    RRDDIM *rd;
-    time_t last_entry_t  = 0;
-
-    rrddim_foreach_read(rd, st) {
-        time_t t = rrddim_last_entry_t(rd);
-        if(t > last_entry_t) last_entry_t = t;
-    }
-
-    return last_entry_t;
-}
-
-static inline time_t rrdset_last_entry_t(RRDSET *st) {
-    time_t last_entry_t;
-
-    netdata_rwlock_rdlock(&st->rrdset_rwlock);
-    last_entry_t = rrdset_last_entry_t_nolock(st);
-    netdata_rwlock_unlock(&st->rrdset_rwlock);
-
-    return last_entry_t;
-}
-
-// get the timestamp of first entry in the round robin database
-static inline time_t rrdset_first_entry_t_nolock(RRDSET *st) {
-    RRDDIM *rd;
-    time_t first_entry_t = LONG_MAX;
-
-    rrddim_foreach_read(rd, st) {
-        time_t t = rrddim_first_entry_t(rd);
-        if(t < first_entry_t)
-            first_entry_t = t;
-    }
-
-    if (unlikely(LONG_MAX == first_entry_t)) return 0;
-    return first_entry_t;
-}
-
-static inline time_t rrdset_first_entry_t(RRDSET *st)
-{
-    time_t first_entry_t;
-
-    netdata_rwlock_rdlock(&st->rrdset_rwlock);
-    first_entry_t = rrdset_first_entry_t_nolock(st);
-    netdata_rwlock_unlock(&st->rrdset_rwlock);
-
-    return first_entry_t;
-}
-
+#define rrdset_is_available_for_viewers(st) (!rrdset_flag_check(st, RRDSET_FLAG_HIDDEN) && !rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE) && !rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED) && rrdset_number_of_dimensions(st) && (st)->rrd_memory_mode != RRD_MEMORY_MODE_NONE)
+#define rrdset_is_available_for_exporting_and_alarms(st) (!rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE) && !rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED) && rrdset_number_of_dimensions(st))
+#define rrdset_is_archived(st) (rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED) && rrdset_number_of_dimensions(st))
+
+time_t rrddim_first_entry_t(RRDDIM *rd);
+time_t rrddim_first_entry_t_of_tier(RRDDIM *rd, size_t tier);
+time_t rrddim_last_entry_t(RRDDIM *rd);
+time_t rrdset_last_entry_t(RRDSET *st);
+time_t rrdset_first_entry_t_of_tier(RRDSET *st, size_t tier);
+time_t rrdset_first_entry_t(RRDSET *st);
 time_t rrdhost_last_entry_t(RRDHOST *h);
 
 // ----------------------------------------------------------------------------
 // RRD DIMENSION functions
 
-extern void rrdcalc_link_to_rrddim(RRDDIM *rd, RRDSET *st, RRDHOST *host);
-extern RRDDIM *rrddim_add_custom(RRDSET *st, const char *id, const char *name, collected_number multiplier,
-                                 collected_number divisor, RRD_ALGORITHM algorithm, RRD_MEMORY_MODE memory_mode);//,
-                                 //int is_archived, uuid_t *dim_uuid);
-#define rrddim_add(st, id, name, multiplier, divisor, algorithm) rrddim_add_custom(st, id, name, multiplier, divisor, \
-                                                                                   algorithm, (st)->rrd_memory_mode)//, 0, NULL)
-
-extern int rrddim_set_name(RRDSET *st, RRDDIM *rd, const char *name);
-extern int rrddim_set_algorithm(RRDSET *st, RRDDIM *rd, RRD_ALGORITHM algorithm);
-extern int rrddim_set_multiplier(RRDSET *st, RRDDIM *rd, collected_number multiplier);
-extern int rrddim_set_divisor(RRDSET *st, RRDDIM *rd, collected_number divisor);
-
-extern RRDDIM *rrddim_find(RRDSET *st, const char *id);
-/* This will not return dimensions that are archived */
-static inline RRDDIM *rrddim_find_active(RRDSET *st, const char *id)
-{
-    RRDDIM *rd = rrddim_find(st, id);
-    if (unlikely(rd && rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)))
-        return NULL;
-    return rd;
-}
+RRDDIM *rrddim_add_custom(RRDSET *st
+                                 , const char *id
+                                 , const char *name
+                                 , collected_number multiplier
+                                 , collected_number divisor
+                                 , RRD_ALGORITHM algorithm
+                                 , RRD_MEMORY_MODE memory_mode
+                                 );
+
+#define rrddim_add(st, id, name, multiplier, divisor, algorithm) \
+    rrddim_add_custom(st, id, name, multiplier, divisor, algorithm, (st)->rrd_memory_mode)
 
+int rrddim_reset_name(RRDSET *st, RRDDIM *rd, const char *name);
+int rrddim_set_algorithm(RRDSET *st, RRDDIM *rd, RRD_ALGORITHM algorithm);
+int rrddim_set_multiplier(RRDSET *st, RRDDIM *rd, collected_number multiplier);
+int rrddim_set_divisor(RRDSET *st, RRDDIM *rd, collected_number divisor);
 
-extern int rrddim_hide(RRDSET *st, const char *id);
-extern int rrddim_unhide(RRDSET *st, const char *id);
+RRDDIM *rrddim_find(RRDSET *st, const char *id);
+RRDDIM_ACQUIRED *rrddim_find_and_acquire(RRDSET *st, const char *id);
+RRDDIM *rrddim_acquired_to_rrddim(RRDDIM_ACQUIRED *rda);
+void rrddim_acquired_release(RRDDIM_ACQUIRED *rda);
+RRDDIM *rrddim_find_active(RRDSET *st, const char *id);
 
-extern void rrddim_is_obsolete(RRDSET *st, RRDDIM *rd);
-extern void rrddim_isnot_obsolete(RRDSET *st, RRDDIM *rd);
+int rrddim_hide(RRDSET *st, const char *id);
+int rrddim_unhide(RRDSET *st, const char *id);
+
+void rrddim_is_obsolete(RRDSET *st, RRDDIM *rd);
+void rrddim_isnot_obsolete(RRDSET *st, RRDDIM *rd);
+
+collected_number rrddim_timed_set_by_pointer(RRDSET *st, RRDDIM *rd, struct timeval collected_time, collected_number value);
+collected_number rrddim_set_by_pointer(RRDSET *st, RRDDIM *rd, collected_number value);
+collected_number rrddim_set(RRDSET *st, const char *id, collected_number value);
 
-extern collected_number rrddim_set_by_pointer(RRDSET *st, RRDDIM *rd, collected_number value);
-extern collected_number rrddim_set(RRDSET *st, const char *id, collected_number value);
 #ifdef ENABLE_ACLK
-extern time_t calc_dimension_liveness(RRDDIM *rd, time_t now);
+time_t calc_dimension_liveness(RRDDIM *rd, time_t now);
+#endif
+long align_entries_to_pagesize(RRD_MEMORY_MODE mode, long entries);
+
+#ifdef NETDATA_LOG_COLLECTION_ERRORS
+#define rrddim_store_metric(rd, point_end_time_ut, n, flags) rrddim_store_metric_with_trace(rd, point_end_time_ut, n, flags, __FUNCTION__)
+void rrddim_store_metric_with_trace(RRDDIM *rd, usec_t point_end_time_ut, NETDATA_DOUBLE n, SN_FLAGS flags, const char *function);
+#else
+void rrddim_store_metric(RRDDIM *rd, usec_t point_end_time_ut, NETDATA_DOUBLE n, SN_FLAGS flags);
 #endif
-extern long align_entries_to_pagesize(RRD_MEMORY_MODE mode, long entries);
 
 // ----------------------------------------------------------------------------
 // Miscellaneous functions
 
-extern int alarm_compare_id(void *a, void *b);
-extern int alarm_compare_name(void *a, void *b);
+char *rrdset_strncpyz_name(char *to, const char *from, size_t length);
 
 // ----------------------------------------------------------------------------
 // RRD internal functions
 
-#ifdef NETDATA_RRD_INTERNALS
-
-extern avl_tree_lock rrdhost_root_index;
+void rrdset_delete_files(RRDSET *st);
+void rrdset_save(RRDSET *st);
+void rrdset_free(RRDSET *st);
 
-extern char *rrdset_strncpyz_name(char *to, const char *from, size_t length);
-extern char *rrdset_cache_dir(RRDHOST *host, const char *id);
-
-extern void rrddim_free(RRDSET *st, RRDDIM *rd);
-
-extern int rrddim_compare(void* a, void* b);
-extern int rrdset_compare(void* a, void* b);
-extern int rrdset_compare_name(void* a, void* b);
-extern int rrdfamily_compare(void *a, void *b);
+#ifdef NETDATA_RRD_INTERNALS
 
-extern RRDFAMILY *rrdfamily_create(RRDHOST *host, const char *id);
-extern void rrdfamily_free(RRDHOST *host, RRDFAMILY *rc);
+char *rrdset_cache_dir(RRDHOST *host, const char *id);
 
-#define rrdset_index_add(host, st) (RRDSET *)avl_insert_lock(&((host)->rrdset_root_index), (avl_t *)(st))
-#define rrdset_index_del(host, st) (RRDSET *)avl_remove_lock(&((host)->rrdset_root_index), (avl_t *)(st))
-extern RRDSET *rrdset_index_del_name(RRDHOST *host, RRDSET *st);
+void rrddim_free(RRDSET *st, RRDDIM *rd);
 
-extern void rrdset_free(RRDSET *st);
-extern void rrdset_reset(RRDSET *st);
-extern void rrdset_save(RRDSET *st);
-extern void rrdset_delete_files(RRDSET *st);
-extern void rrdset_delete_obsolete_dimensions(RRDSET *st);
+void rrdset_reset(RRDSET *st);
+void rrdset_delete_obsolete_dimensions(RRDSET *st);
 
-extern RRDHOST *rrdhost_create(
+RRDHOST *rrdhost_create(
     const char *hostname, const char *registry_hostname, const char *guid, const char *os, const char *timezone,
     const char *abbrev_timezone, int32_t utc_offset,const char *tags, const char *program_name, const char *program_version,
     int update_every, long entries, RRD_MEMORY_MODE memory_mode, unsigned int health_enabled, unsigned int rrdpush_enabled,
-    char *rrdpush_destination, char *rrdpush_api_key, char *rrdpush_send_charts_matching, struct rrdhost_system_info *system_info,
-    int is_localhost, bool is_archived);
+    char *rrdpush_destination, char *rrdpush_api_key, char *rrdpush_send_charts_matching,
+    bool rrdpush_enable_replication, time_t rrdpush_seconds_to_replicate, time_t rrdpush_replication_step,
+    struct rrdhost_system_info *system_info, int is_localhost, bool is_archived);
 
 #endif /* NETDATA_RRD_INTERNALS */
 
-extern void set_host_properties(
-    RRDHOST *host, int update_every, RRD_MEMORY_MODE memory_mode, const char *hostname, const char *registry_hostname,
-    const char *guid, const char *os, const char *tags, const char *tzone, const char *abbrev_tzone, int32_t utc_offset,
+void set_host_properties(
+    RRDHOST *host, int update_every, RRD_MEMORY_MODE memory_mode, const char *registry_hostname,
+    const char *os, const char *tags, const char *tzone, const char *abbrev_tzone, int32_t utc_offset,
     const char *program_name, const char *program_version);
 
-extern int get_tier_grouping(int tier);
+size_t get_tier_grouping(size_t tier);
 
 // ----------------------------------------------------------------------------
 // RRD DB engine declarations
@@ -1331,8 +1400,8 @@ extern int get_tier_grouping(int tier);
 #endif
 #include "sqlite/sqlite_functions.h"
 #include "sqlite/sqlite_context.h"
+#include "sqlite/sqlite_metadata.h"
 #include "sqlite/sqlite_aclk.h"
-#include "sqlite/sqlite_aclk_chart.h"
 #include "sqlite/sqlite_aclk_alert.h"
 #include "sqlite/sqlite_aclk_node.h"
 #include "sqlite/sqlite_health.h"
diff --git a/database/rrdcalc.c b/database/rrdcalc.c
index cab60468b..aad945a90 100644
--- a/database/rrdcalc.c
+++ b/database/rrdcalc.c
@@ -1,10 +1,9 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
-#define NETDATA_HEALTH_INTERNALS
 #include "rrd.h"
 
 // ----------------------------------------------------------------------------
-// RRDCALC management
+// RRDCALC helpers
 
 inline const char *rrdcalc_status2string(RRDCALC_STATUS status) {
     switch(status) {
@@ -35,55 +34,219 @@ inline const char *rrdcalc_status2string(RRDCALC_STATUS status) {
     }
 }
 
-static void rrdsetcalc_link(RRDSET *st, RRDCALC *rc) {
+uint32_t rrdcalc_get_unique_id(RRDHOST *host, STRING *chart, STRING *name, uint32_t *next_event_id) {
+    netdata_rwlock_rdlock(&host->health_log.alarm_log_rwlock);
+
+    // re-use old IDs, by looking them up in the alarm log
+    ALARM_ENTRY *ae = NULL;
+    for(ae = host->health_log.alarms; ae ;ae = ae->next) {
+        if(unlikely(name == ae->name && chart == ae->chart)) {
+            if(next_event_id) *next_event_id = ae->alarm_event_id + 1;
+            break;
+        }
+    }
+
+    uint32_t alarm_id;
+
+    if(ae)
+        alarm_id = ae->alarm_id;
+
+    else {
+        if (unlikely(!host->health_log.next_alarm_id))
+            host->health_log.next_alarm_id = (uint32_t)now_realtime_sec();
+
+        alarm_id = host->health_log.next_alarm_id++;
+    }
+
+    netdata_rwlock_unlock(&host->health_log.alarm_log_rwlock);
+    return alarm_id;
+}
+
+// ----------------------------------------------------------------------------
+// RRDCALC replacing info text variables with RRDSET labels
+
+static STRING *rrdcalc_replace_variables_with_rrdset_labels(const char *line, RRDCALC *rc) {
+    if (!line || !*line)
+        return NULL;
+
+    size_t pos = 0;
+    char *temp = strdupz(line);
+    char var[RRDCALC_VAR_MAX];
+    char *m, *lbl_value = NULL;
+
+    while ((m = strchr(temp + pos, '$'))) {
+        int i = 0;
+        char *e = m;
+        while (*e) {
+
+            if (*e == ' ' || i == RRDCALC_VAR_MAX - 1)
+                break;
+            else
+                var[i] = *e;
+
+            e++;
+            i++;
+        }
+
+        var[i] = '\0';
+        pos = m - temp + 1;
+
+        if (!strcmp(var, RRDCALC_VAR_FAMILY)) {
+            char *buf = find_and_replace(temp, var, (rc->rrdset && rc->rrdset->family) ? rrdset_family(rc->rrdset) : "", m);
+            freez(temp);
+            temp = buf;
+        }
+        else if (!strncmp(var, RRDCALC_VAR_LABEL, RRDCALC_VAR_LABEL_LEN)) {
+            if(likely(rc->rrdset && rc->rrdset->rrdlabels)) {
+                rrdlabels_get_value_to_char_or_null(rc->rrdset->rrdlabels, &lbl_value, var+RRDCALC_VAR_LABEL_LEN);
+                if (lbl_value) {
+                    char *buf = find_and_replace(temp, var, lbl_value, m);
+                    freez(temp);
+                    temp = buf;
+                    freez(lbl_value);
+                }
+            }
+        }
+    }
+
+    STRING *ret = string_strdupz(temp);
+    freez(temp);
+
+    return ret;
+}
+
+void rrdcalc_update_info_using_rrdset_labels(RRDCALC *rc) {
+    if(!rc->rrdset || !rc->original_info || !rc->rrdset->rrdlabels) return;
+
+    size_t labels_version = dictionary_version(rc->rrdset->rrdlabels);
+    if(rc->labels_version != labels_version) {
+
+        STRING *old = rc->info;
+        rc->info = rrdcalc_replace_variables_with_rrdset_labels(rrdcalc_original_info(rc), rc);
+        string_freez(old);
+
+        rc->labels_version = labels_version;
+    }
+}
+
+// ----------------------------------------------------------------------------
+// RRDCALC index management for RRDSET
+
+// the dictionary requires a unique key for every item
+// we use {chart id}.{alert name} for both the RRDHOST and RRDSET alert indexes.
+
+#define RRDCALC_MAX_KEY_SIZE 1024
+static size_t rrdcalc_key(char *dst, size_t dst_len, const char *chart, const char *alert) {
+    return snprintfz(dst, dst_len, "%s/%s", chart, alert);
+}
+
+const RRDCALC_ACQUIRED *rrdcalc_from_rrdset_get(RRDSET *st, const char *alert_name) {
+    char key[RRDCALC_MAX_KEY_SIZE + 1];
+    size_t key_len = rrdcalc_key(key, RRDCALC_MAX_KEY_SIZE, rrdset_id(st), alert_name);
+
+    const RRDCALC_ACQUIRED *rca = (const RRDCALC_ACQUIRED *)dictionary_get_and_acquire_item_advanced(st->rrdhost->rrdcalc_root_index, key, (ssize_t)(key_len + 1));
+
+    if(!rca) {
+        key_len = rrdcalc_key(key, RRDCALC_MAX_KEY_SIZE, rrdset_name(st), alert_name);
+        rca = (const RRDCALC_ACQUIRED *)dictionary_get_and_acquire_item_advanced(st->rrdhost->rrdcalc_root_index, key, (ssize_t)(key_len + 1));
+    }
+
+    return rca;
+}
+
+void rrdcalc_from_rrdset_release(RRDSET *st, const RRDCALC_ACQUIRED *rca) {
+    if(!rca) return;
+
+    dictionary_acquired_item_release(st->rrdhost->rrdcalc_root_index, (const DICTIONARY_ITEM *)rca);
+}
+
+RRDCALC *rrdcalc_acquired_to_rrdcalc(const RRDCALC_ACQUIRED *rca) {
+    if(rca)
+        return dictionary_acquired_item_value((const DICTIONARY_ITEM *)rca);
+
+    return NULL;
+}
+
+// ----------------------------------------------------------------------------
+// RRDCALC managing the linking with RRDSET
+
+static void rrdcalc_link_to_rrdset(RRDSET *st, RRDCALC *rc) {
     RRDHOST *host = st->rrdhost;
 
-    debug(D_HEALTH, "Health linking alarm '%s.%s' to chart '%s' of host '%s'", rc->chart?rc->chart:"NOCHART", rc->name, st->id, host->hostname);
+    debug(D_HEALTH, "Health linking alarm '%s.%s' to chart '%s' of host '%s'", rrdcalc_chart_name(rc), rrdcalc_name(rc), rrdset_id(st), rrdhost_hostname(host));
 
     rc->last_status_change = now_realtime_sec();
     rc->rrdset = st;
 
-    rc->rrdset_next = st->alarms;
-    rc->rrdset_prev = NULL;
-
-    if(rc->rrdset_next)
-        rc->rrdset_next->rrdset_prev = rc;
-
-    st->alarms = rc;
+    netdata_rwlock_wrlock(&st->alerts.rwlock);
+    DOUBLE_LINKED_LIST_APPEND_UNSAFE(st->alerts.base, rc, prev, next);
+    netdata_rwlock_unlock(&st->alerts.rwlock);
 
     if(rc->update_every < rc->rrdset->update_every) {
-        error("Health alarm '%s.%s' has update every %d, less than chart update every %d. Setting alarm update frequency to %d.", rc->rrdset->id, rc->name, rc->update_every, rc->rrdset->update_every, rc->rrdset->update_every);
+        error("Health alarm '%s.%s' has update every %d, less than chart update every %d. Setting alarm update frequency to %d.", rrdset_id(rc->rrdset), rrdcalc_name(rc), rc->update_every, rc->rrdset->update_every, rc->rrdset->update_every);
         rc->update_every = rc->rrdset->update_every;
     }
 
     if(!isnan(rc->green) && isnan(st->green)) {
         debug(D_HEALTH, "Health alarm '%s.%s' green threshold set from " NETDATA_DOUBLE_FORMAT_AUTO
-            " to " NETDATA_DOUBLE_FORMAT_AUTO ".", rc->rrdset->id, rc->name, rc->rrdset->green, rc->green);
+                        " to " NETDATA_DOUBLE_FORMAT_AUTO ".", rrdset_id(rc->rrdset), rrdcalc_name(rc), rc->rrdset->green, rc->green);
         st->green = rc->green;
     }
 
     if(!isnan(rc->red) && isnan(st->red)) {
         debug(D_HEALTH, "Health alarm '%s.%s' red threshold set from " NETDATA_DOUBLE_FORMAT_AUTO " to " NETDATA_DOUBLE_FORMAT_AUTO
-            ".", rc->rrdset->id, rc->name, rc->rrdset->red, rc->red);
+                        ".", rrdset_id(rc->rrdset), rrdcalc_name(rc), rc->rrdset->red, rc->red);
         st->red = rc->red;
     }
 
-    rc->local  = rrdvar_create_and_index("local",  &st->rrdvar_root_index, rc->name, RRDVAR_TYPE_CALCULATED, RRDVAR_OPTION_RRDCALC_LOCAL_VAR, &rc->value);
-    rc->family = rrdvar_create_and_index("family", &st->rrdfamily->rrdvar_root_index, rc->name, RRDVAR_TYPE_CALCULATED, RRDVAR_OPTION_RRDCALC_FAMILY_VAR, &rc->value);
-
-    char fullname[RRDVAR_MAX_LENGTH + 1];
-    snprintfz(fullname, RRDVAR_MAX_LENGTH, "%s.%s", st->id, rc->name);
-    rc->hostid   = rrdvar_create_and_index("host", &host->rrdvar_root_index, fullname, RRDVAR_TYPE_CALCULATED, RRDVAR_OPTION_RRDCALC_HOST_CHARTID_VAR, &rc->value);
+    char buf[RRDVAR_MAX_LENGTH + 1];
+    snprintfz(buf, RRDVAR_MAX_LENGTH, "%s.%s", rrdset_name(st), rrdcalc_name(rc));
+    STRING *rrdset_name_rrdcalc_name = string_strdupz(buf);
+    snprintfz(buf, RRDVAR_MAX_LENGTH, "%s.%s", rrdset_id(st), rrdcalc_name(rc));
+    STRING *rrdset_id_rrdcalc_name = string_strdupz(buf);
 
-    snprintfz(fullname, RRDVAR_MAX_LENGTH, "%s.%s", st->name, rc->name);
-    rc->hostname = rrdvar_create_and_index("host", &host->rrdvar_root_index, fullname, RRDVAR_TYPE_CALCULATED, RRDVAR_OPTION_RRDCALC_HOST_CHARTNAME_VAR, &rc->value);
-
-    if(rc->hostid && !rc->hostname)
-        rc->hostid->options |= RRDVAR_OPTION_RRDCALC_HOST_CHARTNAME_VAR;
+    rc->rrdvar_local = rrdvar_add_and_acquire(
+        "local",
+        st->rrdvars,
+        rc->name,
+        RRDVAR_TYPE_CALCULATED,
+        RRDVAR_FLAG_RRDCALC_LOCAL_VAR,
+        &rc->value);
 
-    if(!rc->units) rc->units = strdupz(st->units);
+    rc->rrdvar_family = rrdvar_add_and_acquire(
+        "family",
+        rrdfamily_rrdvars_dict(st->rrdfamily),
+        rc->name,
+        RRDVAR_TYPE_CALCULATED,
+        RRDVAR_FLAG_RRDCALC_FAMILY_VAR,
+        &rc->value);
+
+    rc->rrdvar_host_chart_name = rrdvar_add_and_acquire(
+        "host",
+        host->rrdvars,
+        rrdset_name_rrdcalc_name,
+        RRDVAR_TYPE_CALCULATED,
+        RRDVAR_FLAG_RRDCALC_HOST_CHARTNAME_VAR,
+        &rc->value);
+
+    rc->rrdvar_host_chart_id = rrdvar_add_and_acquire(
+        "host",
+        host->rrdvars,
+        rrdset_id_rrdcalc_name,
+        RRDVAR_TYPE_CALCULATED,
+        RRDVAR_FLAG_RRDCALC_HOST_CHARTID_VAR | ((rc->rrdvar_host_chart_name) ? 0 : RRDVAR_FLAG_RRDCALC_HOST_CHARTNAME_VAR),
+        &rc->value);
+
+    string_freez(rrdset_id_rrdcalc_name);
+    string_freez(rrdset_name_rrdcalc_name);
+
+    if(!rc->units)
+        rc->units = string_dup(st->units);
+
+    rrdcalc_update_info_using_rrdset_labels(rc);
 
     time_t now = now_realtime_sec();
+
     ALARM_ENTRY *ae = health_create_alarm_entry(
         host,
         rc->id,
@@ -108,216 +271,224 @@ static void rrdsetcalc_link(RRDSET *st, RRDCALC *rc) {
         rc->units,
         rc->info,
         0,
-        0);
-    health_alarm_log(host, ae);
-}
-
-static int rrdcalc_is_matching_rrdset(RRDCALC *rc, RRDSET *st) {
-    if((rc->hash_chart != st->hash || strcmp(rc->chart, st->id) != 0) &&
-        (rc->hash_chart != st->hash_name || strcmp(rc->chart, st->name) != 0))
-        return 0;
-
-    if (rc->module_pattern && !simple_pattern_matches(rc->module_pattern, st->module_name))
-        return 0;
-
-    if (rc->plugin_pattern && !simple_pattern_matches(rc->plugin_pattern, st->plugin_name))
-        return 0;
+        rrdcalc_isrepeating(rc)?HEALTH_ENTRY_FLAG_IS_REPEATING:0);
 
-    if (st->rrdhost->host_labels && rc->host_labels_pattern && !rrdlabels_match_simple_pattern_parsed(st->rrdhost->host_labels, rc->host_labels_pattern, '='))
-        return 0;
-
-    return 1;
-}
-
-// this has to be called while the RRDHOST is locked
-inline void rrdsetcalc_link_matching(RRDSET *st) {
-    RRDHOST *host = st->rrdhost;
-    // debug(D_HEALTH, "find matching alarms for chart '%s'", st->id);
-
-    RRDCALC *rc;
-    for(rc = host->alarms; rc ; rc = rc->next) {
-        if(unlikely(rc->rrdset))
-            continue;
-
-        if(unlikely(rrdcalc_is_matching_rrdset(rc, st)))
-            rrdsetcalc_link(st, rc);
-    }
+    health_alarm_log_add_entry(host, ae);
 }
 
-// this has to be called while the RRDHOST is locked
-inline void rrdsetcalc_unlink(RRDCALC *rc) {
+static void rrdcalc_unlink_from_rrdset(RRDCALC *rc, bool having_ll_wrlock) {
     RRDSET *st = rc->rrdset;
 
     if(!st) {
-        debug(D_HEALTH, "Requested to unlink RRDCALC '%s.%s' which is not linked to any RRDSET", rc->chart?rc->chart:"NOCHART", rc->name);
-        error("Requested to unlink RRDCALC '%s.%s' which is not linked to any RRDSET", rc->chart?rc->chart:"NOCHART", rc->name);
+        debug(D_HEALTH, "Requested to unlink RRDCALC '%s.%s' which is not linked to any RRDSET", rrdcalc_chart_name(rc), rrdcalc_name(rc));
+        error("Requested to unlink RRDCALC '%s.%s' which is not linked to any RRDSET", rrdcalc_chart_name(rc), rrdcalc_name(rc));
         return;
     }
 
     RRDHOST *host = st->rrdhost;
 
     time_t now = now_realtime_sec();
-    ALARM_ENTRY *ae = health_create_alarm_entry(
-        host,
-        rc->id,
-        rc->next_event_id++,
-        rc->config_hash_id,
-        now,
-        rc->name,
-        rc->rrdset->id,
-        rc->rrdset->context,
-        rc->rrdset->family,
-        rc->classification,
-        rc->component,
-        rc->type,
-        rc->exec,
-        rc->recipient,
-        now - rc->last_status_change,
-        rc->old_value,
-        rc->value,
-        rc->status,
-        RRDCALC_STATUS_REMOVED,
-        rc->source,
-        rc->units,
-        rc->info,
-        0,
-        0);
-    health_alarm_log(host, ae);
 
-    debug(D_HEALTH, "Health unlinking alarm '%s.%s' from chart '%s' of host '%s'", rc->chart?rc->chart:"NOCHART", rc->name, st->id, host->hostname);
+    if (likely(rc->status != RRDCALC_STATUS_REMOVED)) {
+        ALARM_ENTRY *ae = health_create_alarm_entry(
+            host,
+            rc->id,
+            rc->next_event_id++,
+            rc->config_hash_id,
+            now,
+            rc->name,
+            rc->rrdset->id,
+            rc->rrdset->context,
+            rc->rrdset->family,
+            rc->classification,
+            rc->component,
+            rc->type,
+            rc->exec,
+            rc->recipient,
+            now - rc->last_status_change,
+            rc->old_value,
+            rc->value,
+            rc->status,
+            RRDCALC_STATUS_REMOVED,
+            rc->source,
+            rc->units,
+            rc->info,
+            0,
+            0);
+
+        health_alarm_log_add_entry(host, ae);
+    }
+
+    debug(D_HEALTH, "Health unlinking alarm '%s.%s' from chart '%s' of host '%s'", rrdcalc_chart_name(rc), rrdcalc_name(rc), rrdset_id(st), rrdhost_hostname(host));
 
     // unlink it
-    if(rc->rrdset_prev)
-        rc->rrdset_prev->rrdset_next = rc->rrdset_next;
 
-    if(rc->rrdset_next)
-        rc->rrdset_next->rrdset_prev = rc->rrdset_prev;
+    if(!having_ll_wrlock)
+        netdata_rwlock_wrlock(&st->alerts.rwlock);
 
-    if(st->alarms == rc)
-        st->alarms = rc->rrdset_next;
+    DOUBLE_LINKED_LIST_REMOVE_UNSAFE(st->alerts.base, rc, prev, next);
 
-    rc->rrdset_prev = rc->rrdset_next = NULL;
+    if(!having_ll_wrlock)
+        netdata_rwlock_unlock(&st->alerts.rwlock);
 
-    rrdvar_free(host, &st->rrdvar_root_index, rc->local);
-    rc->local = NULL;
+    rc->rrdset = NULL;
 
-    rrdvar_free(host, &st->rrdfamily->rrdvar_root_index, rc->family);
-    rc->family = NULL;
+    rrdvar_release_and_del(st->rrdvars, rc->rrdvar_local);
+    rc->rrdvar_local = NULL;
 
-    rrdvar_free(host, &host->rrdvar_root_index, rc->hostid);
-    rc->hostid = NULL;
+    rrdvar_release_and_del(rrdfamily_rrdvars_dict(st->rrdfamily), rc->rrdvar_family);
+    rc->rrdvar_family = NULL;
 
-    rrdvar_free(host, &host->rrdvar_root_index, rc->hostname);
-    rc->hostname = NULL;
+    rrdvar_release_and_del(host->rrdvars, rc->rrdvar_host_chart_id);
+    rc->rrdvar_host_chart_id = NULL;
 
-    rc->rrdset = NULL;
+    rrdvar_release_and_del(host->rrdvars, rc->rrdvar_host_chart_name);
+    rc->rrdvar_host_chart_name = NULL;
 
     // RRDCALC will remain in RRDHOST
     // so that if the matching chart is found in the future
     // it will be applied automatically
 }
 
-RRDCALC *rrdcalc_find(RRDSET *st, const char *name) {
-    RRDCALC *rc;
-    uint32_t hash = simple_hash(name);
+static inline bool rrdcalc_check_if_it_matches_rrdset(RRDCALC *rc, RRDSET *st) {
+    if (   (rc->chart != st->id)
+        && (rc->chart != st->name))
+        return false;
 
-    for( rc = st->alarms; rc ; rc = rc->rrdset_next ) {
-        if(unlikely(rc->hash == hash && !strcmp(rc->name, name)))
-            return rc;
-    }
+    if (rc->module_pattern && !simple_pattern_matches(rc->module_pattern, rrdset_module_name(st)))
+        return false;
 
-    return NULL;
+    if (rc->plugin_pattern && !simple_pattern_matches(rc->plugin_pattern, rrdset_plugin_name(st)))
+        return false;
+
+    if (st->rrdhost->rrdlabels && rc->host_labels_pattern && !rrdlabels_match_simple_pattern_parsed(st->rrdhost->rrdlabels, rc->host_labels_pattern, '='))
+        return false;
+
+    return true;
 }
 
-inline int rrdcalc_exists(RRDHOST *host, const char *chart, const char *name, uint32_t hash_chart, uint32_t hash_name) {
+void rrdcalc_link_matching_alerts_to_rrdset(RRDSET *st) {
+    RRDHOST *host = st->rrdhost;
+    // debug(D_HEALTH, "find matching alarms for chart '%s'", st->id);
+
     RRDCALC *rc;
+    foreach_rrdcalc_in_rrdhost_read(host, rc) {
+        if(rc->rrdset)
+            continue;
 
-    if(unlikely(!chart)) {
-        error("attempt to find RRDCALC '%s' without giving a chart name", name);
-        return 1;
+        if(unlikely(rrdcalc_check_if_it_matches_rrdset(rc, st)))
+            rrdcalc_link_to_rrdset(st, rc);
     }
+    foreach_rrdcalc_in_rrdhost_done(rc);
+}
 
-    if(unlikely(!hash_chart)) hash_chart = simple_hash(chart);
-    if(unlikely(!hash_name))  hash_name  = simple_hash(name);
+static inline int rrdcalc_check_and_link_rrdset_callback(RRDSET *st, void *rrdcalc) {
+    RRDCALC *rc = rrdcalc;
 
-    // make sure it does not already exist
-    for(rc = host->alarms; rc ; rc = rc->next) {
-        if (unlikely(rc->chart && rc->hash == hash_name && rc->hash_chart == hash_chart && !strcmp(name, rc->name) && !strcmp(chart, rc->chart))) {
-            debug(D_HEALTH, "Health alarm '%s.%s' already exists in host '%s'.", chart, name, host->hostname);
-            info("Health alarm '%s.%s' already exists in host '%s'.", chart, name, host->hostname);
-            return 1;
-        }
+    if(unlikely(rrdcalc_check_if_it_matches_rrdset(rc, st))) {
+        rrdcalc_link_to_rrdset(st, rc);
+        return -1;
     }
 
     return 0;
 }
 
-inline uint32_t rrdcalc_get_unique_id(RRDHOST *host, const char *chart, const char *name, uint32_t *next_event_id) {
-    if(chart && name) {
-        uint32_t hash_chart = simple_hash(chart);
-        uint32_t hash_name = simple_hash(name);
-
-        // re-use old IDs, by looking them up in the alarm log
-        ALARM_ENTRY *ae;
-        for(ae = host->health_log.alarms; ae ;ae = ae->next) {
-            if(unlikely(ae->hash_name == hash_name && ae->hash_chart == hash_chart && !strcmp(name, ae->name) && !strcmp(chart, ae->chart))) {
-                if(next_event_id) *next_event_id = ae->alarm_event_id + 1;
-                return ae->alarm_id;
-            }
+// ----------------------------------------------------------------------------
+// RRDCALC rrdhost index management - constructor
+
+struct rrdcalc_constructor {
+    RRDHOST *rrdhost;                       // the host we operate upon
+    RRDCALC *from_config;                   // points to the original RRDCALC, as loaded from the config
+    RRDCALCTEMPLATE *from_rrdcalctemplate;  // the template this alert is generated from
+    RRDSET *rrdset;                         // when this comes from rrdcalctemplate, we have a matching rrdset
+    const char *overwrite_alert_name;       // when we have a dimension foreach, the alert is renamed
+    const char *overwrite_dimensions;       // when we have a dimension foreach, the dimensions filter is renamed
+
+    enum {
+        RRDCALC_REACT_NONE,
+        RRDCALC_REACT_NEW,
+    } react_action;
+
+    bool existing_from_template;
+};
+
+static void rrdcalc_rrdhost_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdcalc, void *constructor_data) {
+    RRDCALC *rc = rrdcalc;
+    struct rrdcalc_constructor *ctr = constructor_data;
+    RRDHOST *host = ctr->rrdhost;
+
+    rc->key = string_strdupz(dictionary_acquired_item_name(item));
+
+    if(ctr->from_rrdcalctemplate) {
+        rc->run_flags |= RRDCALC_FLAG_FROM_TEMPLATE;
+
+        RRDCALCTEMPLATE *rt = ctr->from_rrdcalctemplate;
+        RRDSET *st = ctr->rrdset;
+
+        rc->next_event_id = 1;
+        rc->name = (ctr->overwrite_alert_name) ? string_strdupz(ctr->overwrite_alert_name) : string_dup(rt->name);
+        rc->chart = string_dup(st->id);
+        uuid_copy(rc->config_hash_id, rt->config_hash_id);
+
+        rc->dimensions = (ctr->overwrite_dimensions) ? string_strdupz(ctr->overwrite_dimensions) : string_dup(rt->dimensions);
+        rc->foreach_dimension = NULL;
+        rc->foreach_dimension_pattern = NULL;
+
+        rc->green = rt->green;
+        rc->red = rt->red;
+        rc->value = NAN;
+        rc->old_value = NAN;
+
+        rc->delay_up_duration = rt->delay_up_duration;
+        rc->delay_down_duration = rt->delay_down_duration;
+        rc->delay_max_duration = rt->delay_max_duration;
+        rc->delay_multiplier = rt->delay_multiplier;
+
+        rc->last_repeat = 0;
+        rc->times_repeat = 0;
+        rc->warn_repeat_every = rt->warn_repeat_every;
+        rc->crit_repeat_every = rt->crit_repeat_every;
+
+        rc->group = rt->group;
+        rc->after = rt->after;
+        rc->before = rt->before;
+        rc->update_every = rt->update_every;
+        rc->options = rt->options;
+
+        rc->exec = string_dup(rt->exec);
+        rc->recipient = string_dup(rt->recipient);
+        rc->source = string_dup(rt->source);
+        rc->units = string_dup(rt->units);
+        rc->info = string_dup(rt->info);
+        rc->original_info = string_dup(rt->info);
+
+        rc->classification = string_dup(rt->classification);
+        rc->component = string_dup(rt->component);
+        rc->type = string_dup(rt->type);
+
+        if(rt->calculation) {
+            rc->calculation = expression_parse(rt->calculation->source, NULL, NULL);
+            if(!rc->calculation)
+                error("Health alarm '%s.%s': failed to parse calculation expression '%s'", rrdset_id(st), rrdcalctemplate_name(rt), rt->calculation->source);
+        }
+        if(rt->warning) {
+            rc->warning = expression_parse(rt->warning->source, NULL, NULL);
+            if(!rc->warning)
+                error("Health alarm '%s.%s': failed to re-parse warning expression '%s'", rrdset_id(st), rrdcalctemplate_name(rt), rt->warning->source);
+        }
+        if(rt->critical) {
+            rc->critical = expression_parse(rt->critical->source, NULL, NULL);
+            if(!rc->critical)
+                error("Health alarm '%s.%s': failed to re-parse critical expression '%s'", rrdset_id(st), rrdcalctemplate_name(rt), rt->critical->source);
         }
     }
-
-    if (unlikely(!host->health_log.next_alarm_id))
-        host->health_log.next_alarm_id = (uint32_t)now_realtime_sec();
-
-    return host->health_log.next_alarm_id++;
-}
-
-/**
- * Alarm name with dimension
- *
- * Change the name of the current alarm appending a new diagram.
- *
- * @param name the alarm name
- * @param namelen is the length of the previous vector.
- * @param dim the dimension of the chart.
- * @param dimlen  is the length of the previous vector.
- *
- * @return It returns the new name on success and the old otherwise
- */
-char *alarm_name_with_dim(char *name, size_t namelen, const char *dim, size_t dimlen) {
-    char *newname,*move;
-
-    newname = mallocz(namelen + dimlen + 2);
-    move = newname;
-    memcpy(move, name, namelen);
-    move += namelen;
-
-    *move++ = '_';
-    memcpy(move, dim, dimlen);
-    move += dimlen;
-    *move = '\0';
-
-    return newname;
-}
-
-/**
- * Remove pipe comma
- *
- * Remove the pipes and commas converting to space.
- *
- * @param str the string to change.
- */
-void dimension_remove_pipe_comma(char *str) {
-    while(*str) {
-        if(*str == '|' || *str == ',') *str = ' ';
-
-        str++;
+    else if(ctr->from_config) {
+        // dictionary has already copied all the members values and pointers
+        // no need for additional work in this case
+        ;
     }
-}
 
-inline void rrdcalc_add_to_host(RRDHOST *host, RRDCALC *rc) {
-    rrdhost_check_rdlock(host);
+    rc->id = rrdcalc_get_unique_id(host, rc->chart, rc->name, &rc->next_event_id);
 
     if(rc->calculation) {
         rc->calculation->status = &rc->status;
@@ -343,351 +514,241 @@ inline void rrdcalc_add_to_host(RRDHOST *host, RRDCALC *rc) {
         rc->critical->rrdcalc = rc;
     }
 
-    if(!rc->foreachdim) {
-        // link it to the host alarms list
-        if(likely(host->alarms)) {
-            // append it
-            RRDCALC *t;
-            for(t = host->alarms; t && t->next ; t = t->next) ;
-            t->next = rc;
-        }
-        else {
-            host->alarms = rc;
-        }
-
-        // link it to its chart
-        RRDSET *st;
-        rrdset_foreach_read(st, host) {
-            if(rrdcalc_is_matching_rrdset(rc, st)) {
-                rrdsetcalc_link(st, rc);
-                break;
-            }
-        }
-    } else {
-        //link it case there is a foreach
-        if(likely(host->alarms_with_foreach)) {
-            // append it
-            RRDCALC *t;
-            for(t = host->alarms_with_foreach; t && t->next ; t = t->next) ;
-            t->next = rc;
-        }
-        else {
-            host->alarms_with_foreach = rc;
-        }
+    debug(D_HEALTH, "Health added alarm '%s.%s': exec '%s', recipient '%s', green " NETDATA_DOUBLE_FORMAT_AUTO
+                    ", red " NETDATA_DOUBLE_FORMAT_AUTO
+                    ", lookup: group %d, after %d, before %d, options %u, dimensions '%s', for each dimension '%s', update every %d, calculation '%s', warning '%s', critical '%s', source '%s', delay up %d, delay down %d, delay max %d, delay_multiplier %f, warn_repeat_every %u, crit_repeat_every %u",
+          rrdcalc_chart_name(rc),
+          rrdcalc_name(rc),
+          (rc->exec)?rrdcalc_exec(rc):"DEFAULT",
+          (rc->recipient)?rrdcalc_recipient(rc):"DEFAULT",
+          rc->green,
+          rc->red,
+          (int)rc->group,
+          rc->after,
+          rc->before,
+          rc->options,
+          (rc->dimensions)?rrdcalc_dimensions(rc):"NONE",
+          (rc->foreach_dimension)?rrdcalc_foreachdim(rc):"NONE",
+          rc->update_every,
+          (rc->calculation)?rc->calculation->parsed_as:"NONE",
+          (rc->warning)?rc->warning->parsed_as:"NONE",
+          (rc->critical)?rc->critical->parsed_as:"NONE",
+          rrdcalc_source(rc),
+          rc->delay_up_duration,
+          rc->delay_down_duration,
+          rc->delay_max_duration,
+          rc->delay_multiplier,
+          rc->warn_repeat_every,
+          rc->crit_repeat_every
+    );
 
-        //I am not linking this alarm direct to the host here, this will be done when the children is created
-    }
+    ctr->react_action = RRDCALC_REACT_NEW;
 }
 
-inline RRDCALC *rrdcalc_create_from_template(RRDHOST *host, RRDCALCTEMPLATE *rt, const char *chart) {
-    debug(D_HEALTH, "Health creating dynamic alarm (from template) '%s.%s'", chart, rt->name);
-
-    if(rrdcalc_exists(host, chart, rt->name, 0, 0))
-        return NULL;
-
-    RRDCALC *rc = callocz(1, sizeof(RRDCALC));
-    rc->next_event_id = 1;
-    rc->name = strdupz(rt->name);
-    rc->hash = simple_hash(rc->name);
-    rc->chart = strdupz(chart);
-    rc->hash_chart = simple_hash(rc->chart);
-    uuid_copy(rc->config_hash_id, rt->config_hash_id);
-
-    rc->id = rrdcalc_get_unique_id(host, rc->chart, rc->name, &rc->next_event_id);
-
-    if(rt->dimensions) rc->dimensions = strdupz(rt->dimensions);
-    if(rt->foreachdim) {
-        rc->foreachdim = strdupz(rt->foreachdim);
-        rc->spdim = health_pattern_from_foreach(rc->foreachdim);
-    }
-    rc->foreachcounter = rt->foreachcounter;
-
-    rc->green = rt->green;
-    rc->red = rt->red;
-    rc->value = NAN;
-    rc->old_value = NAN;
-
-    rc->delay_up_duration = rt->delay_up_duration;
-    rc->delay_down_duration = rt->delay_down_duration;
-    rc->delay_max_duration = rt->delay_max_duration;
-    rc->delay_multiplier = rt->delay_multiplier;
-
-    rc->last_repeat = 0;
-    rc->times_repeat = 0;
-    rc->warn_repeat_every = rt->warn_repeat_every;
-    rc->crit_repeat_every = rt->crit_repeat_every;
-
-    rc->group = rt->group;
-    rc->after = rt->after;
-    rc->before = rt->before;
-    rc->update_every = rt->update_every;
-    rc->options = rt->options;
-
-    if(rt->exec) rc->exec = strdupz(rt->exec);
-    if(rt->recipient) rc->recipient = strdupz(rt->recipient);
-    if(rt->source) rc->source = strdupz(rt->source);
-    if(rt->units) rc->units = strdupz(rt->units);
-    if(rt->info) rc->info = strdupz(rt->info);
-
-    if (rt->classification) rc->classification = strdupz(rt->classification);
-    if (rt->component) rc->component = strdupz(rt->component);
-    if (rt->type) rc->type = strdupz(rt->type);
-
-    if(rt->calculation) {
-        rc->calculation = expression_parse(rt->calculation->source, NULL, NULL);
-        if(!rc->calculation)
-            error("Health alarm '%s.%s': failed to parse calculation expression '%s'", chart, rt->name, rt->calculation->source);
-    }
-    if(rt->warning) {
-        rc->warning = expression_parse(rt->warning->source, NULL, NULL);
-        if(!rc->warning)
-            error("Health alarm '%s.%s': failed to re-parse warning expression '%s'", chart, rt->name, rt->warning->source);
-    }
-    if(rt->critical) {
-        rc->critical = expression_parse(rt->critical->source, NULL, NULL);
-        if(!rc->critical)
-            error("Health alarm '%s.%s': failed to re-parse critical expression '%s'", chart, rt->name, rt->critical->source);
-    }
+static bool rrdcalc_rrdhost_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdcalc, void *rrdcalc_new __maybe_unused, void *constructor_data ) {
+    RRDCALC *rc = rrdcalc;
+    struct rrdcalc_constructor *ctr = constructor_data;
 
-    debug(D_HEALTH, "Health runtime added alarm '%s.%s': exec '%s', recipient '%s', green " NETDATA_DOUBLE_FORMAT_AUTO
-        ", red " NETDATA_DOUBLE_FORMAT_AUTO
-        ", lookup: group %d, after %d, before %d, options %u, dimensions '%s', for each dimension '%s', update every %d, calculation '%s', warning '%s', critical '%s', source '%s', delay up %d, delay down %d, delay max %d, delay_multiplier %f, warn_repeat_every %u, crit_repeat_every %u",
-            (rc->chart)?rc->chart:"NOCHART",
-            rc->name,
-            (rc->exec)?rc->exec:"DEFAULT",
-            (rc->recipient)?rc->recipient:"DEFAULT",
-            rc->green,
-            rc->red,
-            (int)rc->group,
-            rc->after,
-            rc->before,
-            rc->options,
-            (rc->dimensions)?rc->dimensions:"NONE",
-            (rc->foreachdim)?rc->foreachdim:"NONE",
-            rc->update_every,
-            (rc->calculation)?rc->calculation->parsed_as:"NONE",
-            (rc->warning)?rc->warning->parsed_as:"NONE",
-            (rc->critical)?rc->critical->parsed_as:"NONE",
-            rc->source,
-            rc->delay_up_duration,
-            rc->delay_down_duration,
-            rc->delay_max_duration,
-            rc->delay_multiplier,
-            rc->warn_repeat_every,
-            rc->crit_repeat_every
-    );
+    if(rc->run_flags & RRDCALC_FLAG_FROM_TEMPLATE)
+        ctr->existing_from_template = true;
+    else
+        ctr->existing_from_template = false;
 
-    rrdcalc_add_to_host(host, rc);
-    if(!rt->foreachdim) {
-        RRDCALC *rdcmp  = (RRDCALC *) avl_insert_lock(&(host)->alarms_idx_health_log,(avl_t *)rc);
-        if (rdcmp != rc) {
-            error("Cannot insert the alarm index ID %s",rc->name);
-        }
-    }
+    ctr->react_action = RRDCALC_REACT_NONE;
 
-    return rc;
+    return false;
 }
 
-/**
- *  Create from RRDCALC
- *
- *  Create a new alarm using another alarm as template.
- *
- * @param rc is the alarm that will be used as source
- * @param host is the host structure.
- * @param name is the newest chart name.
- * @param dimension is the current dimension
- * @param foreachdim the whole list of dimension
- *
- * @return it returns the new alarm changed.
- */
-inline RRDCALC *rrdcalc_create_from_rrdcalc(RRDCALC *rc, RRDHOST *host, const char *name, const char *dimension) {
-    RRDCALC *newrc = callocz(1, sizeof(RRDCALC));
-
-    newrc->next_event_id = 1;
-    newrc->id = rrdcalc_get_unique_id(host, rc->chart, name, &rc->next_event_id);
-    newrc->name = (char *)name;
-    newrc->hash = simple_hash(newrc->name);
-    newrc->chart = strdupz(rc->chart);
-    newrc->hash_chart = simple_hash(rc->chart);
-    uuid_copy(newrc->config_hash_id, *((uuid_t *) &rc->config_hash_id));
-
-    newrc->dimensions = strdupz(dimension);
-    newrc->foreachdim = NULL;
-    rc->foreachcounter++;
-    newrc->foreachcounter = rc->foreachcounter;
-
-    newrc->green = rc->green;
-    newrc->red = rc->red;
-    newrc->value = NAN;
-    newrc->old_value = NAN;
-
-    newrc->delay_up_duration = rc->delay_up_duration;
-    newrc->delay_down_duration = rc->delay_down_duration;
-    newrc->delay_max_duration = rc->delay_max_duration;
-    newrc->delay_multiplier = rc->delay_multiplier;
-
-    newrc->last_repeat = 0;
-    newrc->times_repeat = 0;
-    newrc->warn_repeat_every = rc->warn_repeat_every;
-    newrc->crit_repeat_every = rc->crit_repeat_every;
-
-    newrc->group = rc->group;
-    newrc->after = rc->after;
-    newrc->before = rc->before;
-    newrc->update_every = rc->update_every;
-    newrc->options = rc->options;
-
-    if(rc->exec) newrc->exec = strdupz(rc->exec);
-    if(rc->recipient) newrc->recipient = strdupz(rc->recipient);
-    if(rc->source) newrc->source = strdupz(rc->source);
-    if(rc->units) newrc->units = strdupz(rc->units);
-    if(rc->info) newrc->info = strdupz(rc->info);
-
-    if (rc->classification) newrc->classification = strdupz(rc->classification);
-    if (rc->component) newrc->component = strdupz(rc->component);
-    if (rc->type) newrc->type = strdupz(rc->type);
+static void rrdcalc_rrdhost_react_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdcalc, void *constructor_data) {
+    RRDCALC *rc = rrdcalc;
+    struct rrdcalc_constructor *ctr = constructor_data;
+    RRDHOST *host = ctr->rrdhost;
 
-    if(rc->calculation) {
-        newrc->calculation = expression_parse(rc->calculation->source, NULL, NULL);
-        if(!newrc->calculation)
-            error("Health alarm '%s.%s': failed to parse calculation expression '%s'", rc->chart, rc->name, rc->calculation->source);
-    }
+    if(ctr->react_action == RRDCALC_REACT_NEW) {
+        if(ctr->rrdset)
+            rrdcalc_link_to_rrdset(ctr->rrdset, rc);
 
-    if(rc->warning) {
-        newrc->warning = expression_parse(rc->warning->source, NULL, NULL);
-        if(!newrc->warning)
-            error("Health alarm '%s.%s': failed to re-parse warning expression '%s'", rc->chart, rc->name, rc->warning->source);
-    }
-
-    if(rc->critical) {
-        newrc->critical = expression_parse(rc->critical->source, NULL, NULL);
-        if(!newrc->critical)
-            error("Health alarm '%s.%s': failed to re-parse critical expression '%s'", rc->chart, rc->name, rc->critical->source);
+        else if (ctr->from_rrdcalctemplate)
+            rrdcontext_foreach_instance_with_rrdset_in_context(host, string2str(ctr->from_rrdcalctemplate->context), rrdcalc_check_and_link_rrdset_callback, rc);
     }
-
-    return newrc;
 }
 
-void rrdcalc_free(RRDCALC *rc) {
+// ----------------------------------------------------------------------------
+// RRDCALC rrdhost index management - destructor
+
+static void rrdcalc_free_internals(RRDCALC *rc) {
     if(unlikely(!rc)) return;
 
     expression_free(rc->calculation);
     expression_free(rc->warning);
     expression_free(rc->critical);
 
-    freez(rc->name);
-    freez(rc->chart);
-    freez(rc->family);
-    freez(rc->dimensions);
-    freez(rc->foreachdim);
-    freez(rc->exec);
-    freez(rc->recipient);
-    freez(rc->source);
-    freez(rc->units);
-    freez(rc->info);
-    freez(rc->classification);
-    freez(rc->component);
-    freez(rc->type);
-    simple_pattern_free(rc->spdim);
-    freez(rc->host_labels);
+    string_freez(rc->key);
+    string_freez(rc->name);
+    string_freez(rc->chart);
+    string_freez(rc->dimensions);
+    string_freez(rc->foreach_dimension);
+    string_freez(rc->exec);
+    string_freez(rc->recipient);
+    string_freez(rc->source);
+    string_freez(rc->units);
+    string_freez(rc->info);
+    string_freez(rc->original_info);
+    string_freez(rc->classification);
+    string_freez(rc->component);
+    string_freez(rc->type);
+    string_freez(rc->host_labels);
+    string_freez(rc->module_match);
+    string_freez(rc->plugin_match);
+
+    simple_pattern_free(rc->foreach_dimension_pattern);
     simple_pattern_free(rc->host_labels_pattern);
-    freez(rc->module_match);
     simple_pattern_free(rc->module_pattern);
-    freez(rc->plugin_match);
     simple_pattern_free(rc->plugin_pattern);
-    freez(rc);
 }
 
-void rrdcalc_unlink_and_free(RRDHOST *host, RRDCALC *rc) {
-    if(unlikely(!rc)) return;
+static void rrdcalc_rrdhost_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdcalc, void *rrdhost __maybe_unused) {
+    RRDCALC *rc = rrdcalc;
+    //RRDHOST *host = rrdhost;
 
-    debug(D_HEALTH, "Health removing alarm '%s.%s' of host '%s'", rc->chart?rc->chart:"NOCHART", rc->name, host->hostname);
+    if(unlikely(rc->rrdset))
+        rrdcalc_unlink_from_rrdset(rc, false);
 
-    // unlink it from RRDSET
-    if(rc->rrdset) rrdsetcalc_unlink(rc);
+    // any destruction actions that require other locks
+    // have to be placed in rrdcalc_del(), because the object is actually locked for deletion
 
-    // unlink it from RRDHOST
-    if(unlikely(rc == host->alarms))
-        host->alarms = rc->next;
-    else {
-        RRDCALC *t;
-        for(t = host->alarms; t && t->next != rc; t = t->next) ;
-        if(t) {
-            t->next = rc->next;
-            rc->next = NULL;
-        }
-        else
-            error("Cannot unlink alarm '%s.%s' from host '%s': not found", rc->chart?rc->chart:"NOCHART", rc->name, host->hostname);
-    }
+    rrdcalc_free_internals(rc);
+}
 
-    RRDCALC *rdcmp = (RRDCALC *) avl_search_lock(&(host)->alarms_idx_health_log, (avl_t *)rc);
-    if (rdcmp) {
-        rdcmp = (RRDCALC *) avl_remove_lock(&(host)->alarms_idx_health_log, (avl_t *)rc);
-        if (!rdcmp) {
-            error("Cannot remove the health alarm index from health_log");
-        }
-    }
+// ----------------------------------------------------------------------------
+// RRDCALC rrdhost index management - index API
 
-    rdcmp = (RRDCALC *) avl_search_lock(&(host)->alarms_idx_name, (avl_t *)rc);
-    if (rdcmp) {
-        rdcmp = (RRDCALC *) avl_remove_lock(&(host)->alarms_idx_name, (avl_t *)rc);
-        if (!rdcmp) {
-            error("Cannot remove the health alarm index from idx_name");
-        }
+void rrdcalc_rrdhost_index_init(RRDHOST *host) {
+    if(!host->rrdcalc_root_index) {
+        host->rrdcalc_root_index = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
+
+        dictionary_register_insert_callback(host->rrdcalc_root_index, rrdcalc_rrdhost_insert_callback, NULL);
+        dictionary_register_conflict_callback(host->rrdcalc_root_index, rrdcalc_rrdhost_conflict_callback, NULL);
+        dictionary_register_react_callback(host->rrdcalc_root_index, rrdcalc_rrdhost_react_callback, NULL);
+        dictionary_register_delete_callback(host->rrdcalc_root_index, rrdcalc_rrdhost_delete_callback, host);
     }
+}
 
-    rrdcalc_free(rc);
+void rrdcalc_rrdhost_index_destroy(RRDHOST *host) {
+    dictionary_destroy(host->rrdcalc_root_index);
+    host->rrdcalc_root_index = NULL;
 }
 
-void rrdcalc_foreach_unlink_and_free(RRDHOST *host, RRDCALC *rc) {
+void rrdcalc_add_from_rrdcalctemplate(RRDHOST *host, RRDCALCTEMPLATE *rt, RRDSET *st, const char *overwrite_alert_name, const char *overwrite_dimensions) {
+    char key[RRDCALC_MAX_KEY_SIZE + 1];
+    size_t key_len = rrdcalc_key(key, RRDCALC_MAX_KEY_SIZE, rrdset_id(st),
+                                 overwrite_alert_name?overwrite_alert_name:string2str(rt->name));
+
+    struct rrdcalc_constructor tmp = {
+        .rrdhost = host,
+        .from_config = NULL,
+        .from_rrdcalctemplate = rt,
+        .rrdset = st,
+        .overwrite_alert_name = overwrite_alert_name,
+        .overwrite_dimensions = overwrite_dimensions,
+        .react_action = RRDCALC_REACT_NONE,
+        .existing_from_template = false,
+    };
+
+    dictionary_set_advanced(host->rrdcalc_root_index, key, (ssize_t)(key_len + 1), NULL, sizeof(RRDCALC), &tmp);
+    if(tmp.react_action != RRDCALC_REACT_NEW && tmp.existing_from_template == false)
+        error("RRDCALC: from template '%s' on chart '%s' with key '%s', failed to be added to host '%s'. It is manually configured.",
+              string2str(rt->name), rrdset_id(st), key, rrdhost_hostname(host));
+}
 
-    if(unlikely(rc == host->alarms_with_foreach))
-        host->alarms_with_foreach = rc->next;
-    else {
-        RRDCALC *t;
-        for(t = host->alarms_with_foreach; t && t->next != rc; t = t->next) ;
-        if(t) {
-            t->next = rc->next;
-            rc->next = NULL;
+int rrdcalc_add_from_config(RRDHOST *host, RRDCALC *rc) {
+    if(!rc->chart) {
+        error("Health configuration for alarm '%s' does not have a chart", rrdcalc_name(rc));
+        return 0;
+    }
+
+    if(!rc->update_every) {
+        error("Health configuration for alarm '%s.%s' has no frequency (parameter 'every'). Ignoring it.", rrdcalc_chart_name(rc), rrdcalc_name(rc));
+        return 0;
+    }
+
+    if(!RRDCALC_HAS_DB_LOOKUP(rc) && !rc->calculation && !rc->warning && !rc->critical) {
+        error("Health configuration for alarm '%s.%s' is useless (no db lookup, no calculation, no warning and no critical expressions)", rrdcalc_chart_name(rc), rrdcalc_name(rc));
+        return 0;
+    }
+
+    char key[RRDCALC_MAX_KEY_SIZE + 1];
+    size_t key_len = rrdcalc_key(key, RRDCALC_MAX_KEY_SIZE, string2str(rc->chart), string2str(rc->name));
+
+    struct rrdcalc_constructor tmp = {
+        .rrdhost = host,
+        .from_config = rc,
+        .from_rrdcalctemplate = NULL,
+        .rrdset = NULL,
+        .react_action = RRDCALC_REACT_NONE,
+    };
+
+    int ret = 1;
+    RRDCALC *t = dictionary_set_advanced(host->rrdcalc_root_index, key, (ssize_t)(key_len + 1), rc, sizeof(RRDCALC), &tmp);
+    if(tmp.react_action == RRDCALC_REACT_NEW) {
+        // we copied rc into the dictionary, so we have to free the container here
+        freez(rc);
+        rc = t;
+
+        // since we loaded this config from configuration, we need to check if we can link it to alarms
+        RRDSET *st;
+        rrdset_foreach_read(st, host) {
+            if (unlikely(rrdcalc_check_and_link_rrdset_callback(st, rc) == -1))
+                break;
         }
-        else
-            error("Cannot unlink alarm '%s.%s' from host '%s': not found", rc->chart?rc->chart:"NOCHART", rc->name, host->hostname);
+        rrdset_foreach_done(st);
     }
+    else {
+        error(
+            "RRDCALC: from config '%s' on chart '%s' failed to be added to host '%s'. It already exists.",
+            string2str(rc->name),
+            string2str(rc->chart),
+            rrdhost_hostname(host));
+
+        ret = 0;
+
+        // free all of it, internals and the container
+        rrdcalc_free_unused_rrdcalc_loaded_from_config(rc);
+    }
+
+    return ret;
+}
 
-    rrdcalc_free(rc);
+static void rrdcalc_unlink_and_delete(RRDHOST *host, RRDCALC *rc, bool having_ll_wrlock) {
+    if(rc->rrdset)
+        rrdcalc_unlink_from_rrdset(rc, having_ll_wrlock);
+
+    dictionary_del_advanced(host->rrdcalc_root_index, string2str(rc->key), (ssize_t)string_strlen(rc->key) + 1);
 }
 
-static void rrdcalc_labels_unlink_alarm_loop(RRDHOST *host, RRDCALC *alarms) {
-    for(RRDCALC *rc = alarms ; rc ; ) {
-        RRDCALC *rc_next = rc->next;
 
-        if (!rc->host_labels) {
-            rc = rc_next;
+// ----------------------------------------------------------------------------
+// RRDCALC cleanup API functions
+
+void rrdcalc_delete_alerts_not_matching_host_labels_from_this_host(RRDHOST *host) {
+    RRDCALC *rc;
+    foreach_rrdcalc_in_rrdhost_reentrant(host, rc) {
+        if (!rc->host_labels)
             continue;
-        }
 
-        if(!rrdlabels_match_simple_pattern_parsed(host->host_labels, rc->host_labels_pattern, '=')) {
+        if(!rrdlabels_match_simple_pattern_parsed(host->rrdlabels, rc->host_labels_pattern, '=')) {
             info("Health configuration for alarm '%s' cannot be applied, because the host %s does not have the label(s) '%s'",
-                 rc->name,
-                 host->hostname,
-                 rc->host_labels);
+                 rrdcalc_name(rc),
+                 rrdhost_hostname(host),
+                 rrdcalc_host_labels(rc));
 
-            if(host->alarms == alarms)
-                rrdcalc_unlink_and_free(host, rc);
-            else
-                rrdcalc_foreach_unlink_and_free(host, rc);
+            rrdcalc_unlink_and_delete(host, rc, false);
         }
-        rc = rc_next;
     }
+    foreach_rrdcalc_in_rrdhost_done(rc);
 }
 
-void rrdcalc_labels_unlink_alarm_from_host(RRDHOST *host) {
-    rrdcalc_labels_unlink_alarm_loop(host, host->alarms);
-    rrdcalc_labels_unlink_alarm_loop(host, host->alarms_with_foreach);
-}
-
-void rrdcalc_labels_unlink() {
+void rrdcalc_delete_alerts_not_matching_host_labels_from_all_hosts() {
     rrd_rdlock();
 
     RRDHOST *host;
@@ -695,70 +756,45 @@ void rrdcalc_labels_unlink() {
         if (unlikely(!host->health_enabled))
             continue;
 
-        if (host->host_labels) {
-            rrdhost_wrlock(host);
-
-            rrdcalc_labels_unlink_alarm_from_host(host);
-
-            rrdhost_unlock(host);
-        }
+        if (host->rrdlabels)
+            rrdcalc_delete_alerts_not_matching_host_labels_from_this_host(host);
     }
 
     rrd_unlock();
 }
 
-// ----------------------------------------------------------------------------
-// Alarm
-
-
-/**
- * Alarm is repeating
- *
- * Is this alarm repeating ?
- *
- * @param host The structure that has the binary tree
- * @param alarm_id the id of the alarm to search
- *
- * @return It returns 1 case it is repeating and 0 otherwise
- */
-int alarm_isrepeating(RRDHOST *host, uint32_t alarm_id) {
-    RRDCALC findme;
-    findme.id = alarm_id;
-    RRDCALC *rc = (RRDCALC *)avl_search_lock(&host->alarms_idx_health_log, (avl_t *)&findme);
-    if (!rc) {
-        return 0;
+void rrdcalc_unlink_all_rrdset_alerts(RRDSET *st) {
+    RRDCALC *rc, *last = NULL;
+    netdata_rwlock_wrlock(&st->alerts.rwlock);
+    while((rc = st->alerts.base)) {
+        if(last == rc) {
+            error("RRDCALC: malformed list of alerts linked to chart - cannot cleanup - giving up.");
+            break;
+        }
+        last = rc;
+
+        if(rc->run_flags & RRDCALC_FLAG_FROM_TEMPLATE) {
+            // if the alert comes from a template we can just delete it
+            rrdcalc_unlink_and_delete(st->rrdhost, rc, true);
+        }
+        else {
+            // this is a configuration for a specific chart
+            // it should stay in the list
+            rrdcalc_unlink_from_rrdset(rc, true);
+        }
+
     }
-    return rrdcalc_isrepeating(rc);
+    netdata_rwlock_unlock(&st->alerts.rwlock);
 }
 
-/**
- * Entry is repeating
- *
- * Check whether the id of alarm entry is yet present in the host structure
- *
- * @param host The structure that has the binary tree
- * @param ae the alarm entry
- *
- * @return It returns 1 case it is repeating and 0 otherwise
- */
-int alarm_entry_isrepeating(RRDHOST *host, ALARM_ENTRY *ae) {
-    return alarm_isrepeating(host, ae->alarm_id);
+void rrdcalc_delete_all(RRDHOST *host) {
+    dictionary_flush(host->rrdcalc_root_index);
 }
 
-/**
- * Max last repeat
- *
- * Check the maximum last_repeat for the alarms associated a host
- *
- * @param host The structure that has the binary tree
- *
- * @return It returns 1 case it is repeating and 0 otherwise
- */
-RRDCALC *alarm_max_last_repeat(RRDHOST *host, char *alarm_name,uint32_t hash) {
-    RRDCALC findme;
-    findme.name = alarm_name;
-    findme.hash = hash;
-    RRDCALC *rc = (RRDCALC *)avl_search_lock(&host->alarms_idx_name, (avl_t *)&findme);
-
-    return rc;
+void rrdcalc_free_unused_rrdcalc_loaded_from_config(RRDCALC *rc) {
+    if(rc->rrdset)
+        rrdcalc_unlink_from_rrdset(rc, false);
+
+    rrdcalc_free_internals(rc);
+    freez(rc);
 }
diff --git a/database/rrdcalc.h b/database/rrdcalc.h
index 0dcd7ce69..a25c05cc6 100644
--- a/database/rrdcalc.h
+++ b/database/rrdcalc.h
@@ -10,55 +10,60 @@
 // (defined in their update_every member below)
 // They increase the overhead of netdata.
 //
-// These calculations are allocated and linked (->next)
-// under RRDHOST.
-// Then are also linked to RRDSET (of course only when the
-// chart is found, via ->rrdset_next and ->rrdset_prev).
-// This double-linked list is maintained sorted at all times
-// having as RRDSET.calculations the RRDCALC to be processed
-// next.
-
-#define RRDCALC_FLAG_DB_ERROR              0x00000001
-#define RRDCALC_FLAG_DB_NAN                0x00000002
-/* #define RRDCALC_FLAG_DB_STALE           0x00000004 */
-#define RRDCALC_FLAG_CALC_ERROR            0x00000008
-#define RRDCALC_FLAG_WARN_ERROR            0x00000010
-#define RRDCALC_FLAG_CRIT_ERROR            0x00000020
-#define RRDCALC_FLAG_RUNNABLE              0x00000040
-#define RRDCALC_FLAG_DISABLED              0x00000080
-#define RRDCALC_FLAG_SILENCED              0x00000100
-#define RRDCALC_FLAG_RUN_ONCE              0x00000200
-#define RRDCALC_FLAG_NO_CLEAR_NOTIFICATION 0x80000000
-
+// These calculations are stored under RRDHOST.
+// Then are also linked to RRDSET (of course only when a
+// matching chart is found).
+
+typedef enum {
+    RRDCALC_FLAG_DB_ERROR                   = (1 << 0),
+    RRDCALC_FLAG_DB_NAN                     = (1 << 1),
+    // RRDCALC_FLAG_DB_STALE                   = (1 << 2),
+    RRDCALC_FLAG_CALC_ERROR                 = (1 << 3),
+    RRDCALC_FLAG_WARN_ERROR                 = (1 << 4),
+    RRDCALC_FLAG_CRIT_ERROR                 = (1 << 5),
+    RRDCALC_FLAG_RUNNABLE                   = (1 << 6),
+    RRDCALC_FLAG_DISABLED                   = (1 << 7),
+    RRDCALC_FLAG_SILENCED                   = (1 << 8),
+    RRDCALC_FLAG_RUN_ONCE                   = (1 << 9),
+    RRDCALC_FLAG_FROM_TEMPLATE              = (1 << 10), // the rrdcalc has been created from a template
+} RRDCALC_FLAGS;
+
+typedef enum {
+    // This list uses several other options from RRDR_OPTIONS for db lookups.
+    // To add an item here, you need to reserve a bit in RRDR_OPTIONS.
+    RRDCALC_OPTION_NO_CLEAR_NOTIFICATION    = 0x80000000,
+} RRDCALC_OPTIONS;
+
+#define RRDCALC_ALL_OPTIONS_EXCLUDING_THE_RRDR_ONES (RRDCALC_OPTION_NO_CLEAR_NOTIFICATION)
 
 struct rrdcalc {
-    avl_t avl;                      // the index, with key the id - this has to be first!
+    STRING *key;                    // the unique key in the host's rrdcalc_root_index
+
     uint32_t id;                    // the unique id of this alarm
     uint32_t next_event_id;         // the next event id that will be used for this alarm
 
-    char *name;                     // the name of this alarm
-    uint32_t hash;                  // the hash of the alarm name
     uuid_t config_hash_id;          // a predictable hash_id based on specific alert configuration
 
-    char *exec;                     // the command to execute when this alarm switches state
-    char *recipient;                // the recipient of the alarm (the first parameter to exec)
+    STRING *name;                   // the name of this alarm
+    STRING *chart;                  // the chart id this should be linked to
 
-    char *classification;           // the class that this alarm belongs
-    char *component;                // the component that this alarm refers to
-    char *type;                     // type of the alarm
+    STRING *exec;                   // the command to execute when this alarm switches state
+    STRING *recipient;              // the recipient of the alarm (the first parameter to exec)
 
-    char *chart;                    // the chart id this should be linked to
-    uint32_t hash_chart;
+    STRING *classification;         // the class that this alarm belongs
+    STRING *component;              // the component that this alarm refers to
+    STRING *type;                   // type of the alarm
 
-    char *plugin_match;             //the plugin name that should be linked to
+    STRING *plugin_match;           // the plugin name that should be linked to
     SIMPLE_PATTERN *plugin_pattern;
 
-    char *module_match;             //the module name that should be linked to
+    STRING *module_match;           // the module name that should be linked to
     SIMPLE_PATTERN *module_pattern;
 
-    char *source;                   // the source of this alarm
-    char *units;                    // the units of the alarm
-    char *info;                     // a short description of the alarm
+    STRING *source;                 // the source of this alarm
+    STRING *units;                  // the units of the alarm
+    STRING *original_info;          // the original info field before any variable replacement
+    STRING *info;                   // a short description of the alarm
 
     int update_every;               // update frequency for the alarm
 
@@ -69,15 +74,13 @@ struct rrdcalc {
     // ------------------------------------------------------------------------
     // database lookup settings
 
-    char *dimensions;               // the chart dimensions
-    char *foreachdim;               // the group of dimensions that the `foreach` will be applied.
-    SIMPLE_PATTERN *spdim;          // used if and only if there is a simple pattern for the chart.
-    int foreachcounter;             // the number of alarms created with foreachdim, this also works as an id of the
-                                    // children
+    STRING *dimensions;             // the chart dimensions
+    STRING *foreach_dimension;      // the group of dimensions that the `foreach` will be applied.
+    SIMPLE_PATTERN *foreach_dimension_pattern; // used if and only if there is a simple pattern for the chart.
     RRDR_GROUPING group;            // grouping method: average, max, etc.
     int before;                     // ending point in time-series
     int after;                      // starting point in time-series
-    uint32_t options;               // calculation options
+    RRDCALC_OPTIONS options;        // configuration options
 
     // ------------------------------------------------------------------------
     // expressions related to the alarm
@@ -98,29 +101,29 @@ struct rrdcalc {
     // ------------------------------------------------------------------------
     // notification repeat settings
 
-    uint32_t warn_repeat_every;     // interval between repeating warning notifications
-    uint32_t crit_repeat_every; // interval between repeating critical notifications
+    uint32_t warn_repeat_every;    // interval between repeating warning notifications
+    uint32_t crit_repeat_every;    // interval between repeating critical notifications
 
     // ------------------------------------------------------------------------
     // Labels settings
-    char *host_labels;                   // the label read from an alarm file
+    STRING *host_labels;                 // the label read from an alarm file
     SIMPLE_PATTERN *host_labels_pattern; // the simple pattern of labels
 
     // ------------------------------------------------------------------------
     // runtime information
 
-    RRDCALC_STATUS old_status; // the old status of the alarm
+    RRDCALC_STATUS old_status;      // the old status of the alarm
     RRDCALC_STATUS status;          // the current status of the alarm
 
-    NETDATA_DOUBLE value;        // the current value of the alarm
-    NETDATA_DOUBLE old_value;    // the previous value of the alarm
+    NETDATA_DOUBLE value;           // the current value of the alarm
+    NETDATA_DOUBLE old_value;       // the previous value of the alarm
 
-    uint32_t rrdcalc_flags;         // check RRDCALC_FLAG_*
+    RRDCALC_FLAGS run_flags;        // check RRDCALC_FLAG_*
 
     time_t last_updated;            // the last update timestamp of the alarm
     time_t next_update;             // the next update timestamp of the alarm
     time_t last_status_change;      // the timestamp of the last time this alarm changed status
-    time_t last_repeat; // the last time the alarm got repeated
+    time_t last_repeat;             // the last time the alarm got repeated
     uint32_t times_repeat;          // number of times the alarm got repeated
 
     time_t db_after;                // the first timestamp evaluated by the db lookup
@@ -134,85 +137,105 @@ struct rrdcalc {
     // ------------------------------------------------------------------------
     // variables this alarm exposes to the rest of the alarms
 
-    RRDVAR *local;
-    RRDVAR *family;
-    RRDVAR *hostid;
-    RRDVAR *hostname;
+    const RRDVAR_ACQUIRED *rrdvar_local;
+    const RRDVAR_ACQUIRED *rrdvar_family;
+    const RRDVAR_ACQUIRED *rrdvar_host_chart_id;
+    const RRDVAR_ACQUIRED *rrdvar_host_chart_name;
 
     // ------------------------------------------------------------------------
     // the chart this alarm it is linked to
 
+    size_t labels_version;
     struct rrdset *rrdset;
 
-    // linking of this alarm on its chart
-    struct rrdcalc *rrdset_next;
-    struct rrdcalc *rrdset_prev;
-
     struct rrdcalc *next;
+    struct rrdcalc *prev;
 };
 
+#define rrdcalc_name(rc) string2str((rc)->name)
+#define rrdcalc_chart_name(rc) string2str((rc)->chart)
+#define rrdcalc_exec(rc) string2str((rc)->exec)
+#define rrdcalc_recipient(rc) string2str((rc)->recipient)
+#define rrdcalc_classification(rc) string2str((rc)->classification)
+#define rrdcalc_component(rc) string2str((rc)->component)
+#define rrdcalc_type(rc) string2str((rc)->type)
+#define rrdcalc_plugin_match(rc) string2str((rc)->plugin_match)
+#define rrdcalc_module_match(rc) string2str((rc)->module_match)
+#define rrdcalc_source(rc) string2str((rc)->source)
+#define rrdcalc_units(rc) string2str((rc)->units)
+#define rrdcalc_original_info(rc) string2str((rc)->original_info)
+#define rrdcalc_info(rc) string2str((rc)->info)
+#define rrdcalc_dimensions(rc) string2str((rc)->dimensions)
+#define rrdcalc_foreachdim(rc) string2str((rc)->foreach_dimension)
+#define rrdcalc_host_labels(rc) string2str((rc)->host_labels)
+
+#define foreach_rrdcalc_in_rrdhost_read(host, rc) \
+    dfe_start_read((host)->rrdcalc_root_index, rc) \
+
+#define foreach_rrdcalc_in_rrdhost_reentrant(host, rc) \
+    dfe_start_reentrant((host)->rrdcalc_root_index, rc)
+
+#define foreach_rrdcalc_in_rrdhost_done(rc) \
+    dfe_done(rc)
+
 struct alert_config {
-    char *alarm;
-    char *template_key;
-    char *os;
-    char *host;
-    char *on;
-    char *families;
-    char *plugin;
-    char *module;
-    char *charts;
-    char *lookup;
-    char *calc;
-    char *warn;
-    char *crit;
-    char *every;
-    char *green;
-    char *red;
-    char *exec;
-    char *to;
-    char *units;
-    char *info;
-    char *classification;
-    char *component;
-    char *type;
-    char *delay;
-    char *options;
-    char *repeat;
-    char *host_labels;
-
-    char *p_db_lookup_dimensions;
-    char *p_db_lookup_method;
+    STRING *alarm;
+    STRING *template_key;
+    STRING *os;
+    STRING *host;
+    STRING *on;
+    STRING *families;
+    STRING *plugin;
+    STRING *module;
+    STRING *charts;
+    STRING *lookup;
+    STRING *calc;
+    STRING *warn;
+    STRING *crit;
+    STRING *every;
+    STRING *green;
+    STRING *red;
+    STRING *exec;
+    STRING *to;
+    STRING *units;
+    STRING *info;
+    STRING *classification;
+    STRING *component;
+    STRING *type;
+    STRING *delay;
+    STRING *options;
+    STRING *repeat;
+    STRING *host_labels;
+
+    STRING *p_db_lookup_dimensions;
+    STRING *p_db_lookup_method;
+
     uint32_t p_db_lookup_options;
     int32_t p_db_lookup_after;
     int32_t p_db_lookup_before;
     int32_t p_update_every;
 };
 
-extern int alarm_isrepeating(RRDHOST *host, uint32_t alarm_id);
-extern int alarm_entry_isrepeating(RRDHOST *host, ALARM_ENTRY *ae);
-extern RRDCALC *alarm_max_last_repeat(RRDHOST *host, char *alarm_name, uint32_t hash);
-
 #define RRDCALC_HAS_DB_LOOKUP(rc) ((rc)->after)
 
-extern void rrdsetcalc_link_matching(RRDSET *st);
-extern void rrdsetcalc_unlink(RRDCALC *rc);
-extern RRDCALC *rrdcalc_find(RRDSET *st, const char *name);
+void rrdcalc_update_info_using_rrdset_labels(RRDCALC *rc);
 
-extern const char *rrdcalc_status2string(RRDCALC_STATUS status);
+void rrdcalc_link_matching_alerts_to_rrdset(RRDSET *st);
 
-extern void rrdcalc_free(RRDCALC *rc);
-extern void rrdcalc_unlink_and_free(RRDHOST *host, RRDCALC *rc);
+const RRDCALC_ACQUIRED *rrdcalc_from_rrdset_get(RRDSET *st, const char *alert_name);
+void rrdcalc_from_rrdset_release(RRDSET *st, const RRDCALC_ACQUIRED *rca);
+RRDCALC *rrdcalc_acquired_to_rrdcalc(const RRDCALC_ACQUIRED *rca);
 
-extern int rrdcalc_exists(RRDHOST *host, const char *chart, const char *name, uint32_t hash_chart, uint32_t hash_name);
-extern uint32_t rrdcalc_get_unique_id(RRDHOST *host, const char *chart, const char *name, uint32_t *next_event_id);
-extern RRDCALC *rrdcalc_create_from_template(RRDHOST *host, RRDCALCTEMPLATE *rt, const char *chart);
-extern RRDCALC *rrdcalc_create_from_rrdcalc(RRDCALC *rc, RRDHOST *host, const char *name, const char *dimension);
-extern void rrdcalc_add_to_host(RRDHOST *host, RRDCALC *rc);
-extern void dimension_remove_pipe_comma(char *str);
-extern char *alarm_name_with_dim(char *name, size_t namelen, const char *dim, size_t dimlen);
+const char *rrdcalc_status2string(RRDCALC_STATUS status);
 
-extern void rrdcalc_labels_unlink();
-extern void rrdcalc_labels_unlink_alarm_from_host(RRDHOST *host);
+void rrdcalc_free_unused_rrdcalc_loaded_from_config(RRDCALC *rc);
+
+uint32_t rrdcalc_get_unique_id(RRDHOST *host, STRING *chart, STRING *name, uint32_t *next_event_id);
+void rrdcalc_add_from_rrdcalctemplate(RRDHOST *host, RRDCALCTEMPLATE *rt, RRDSET *st, const char *overwrite_alert_name, const char *overwrite_dimensions);
+int rrdcalc_add_from_config(RRDHOST *host, RRDCALC *rc);
+
+void rrdcalc_delete_alerts_not_matching_host_labels_from_all_hosts();
+void rrdcalc_delete_alerts_not_matching_host_labels_from_this_host(RRDHOST *host);
 
 static inline int rrdcalc_isrepeating(RRDCALC *rc) {
     if (unlikely(rc->warn_repeat_every > 0 || rc->crit_repeat_every > 0)) {
@@ -221,4 +244,15 @@ static inline int rrdcalc_isrepeating(RRDCALC *rc) {
     return 0;
 }
 
+void rrdcalc_unlink_all_rrdset_alerts(RRDSET *st);
+void rrdcalc_delete_all(RRDHOST *host);
+
+void rrdcalc_rrdhost_index_init(RRDHOST *host);
+void rrdcalc_rrdhost_index_destroy(RRDHOST *host);
+
+#define RRDCALC_VAR_MAX 100
+#define RRDCALC_VAR_FAMILY "$family"
+#define RRDCALC_VAR_LABEL "$label:"
+#define RRDCALC_VAR_LABEL_LEN (sizeof(RRDCALC_VAR_LABEL)-1)
+
 #endif //NETDATA_RRDCALC_H
diff --git a/database/rrdcalctemplate.c b/database/rrdcalctemplate.c
index 3f9804b93..87e085c93 100644
--- a/database/rrdcalctemplate.c
+++ b/database/rrdcalctemplate.c
@@ -1,6 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
-#define NETDATA_HEALTH_INTERNALS
 #include "rrd.h"
 
 // ----------------------------------------------------------------------------
@@ -11,100 +10,232 @@
  * @param rt is the template used to create the chart.
  * @param st is the chart where the alarm will be attached.
  */
-void rrdcalctemplate_check_conditions_and_link(RRDCALCTEMPLATE *rt, RRDSET *st, RRDHOST *host) {
-    if(rt->hash_context != st->hash_context || strcmp(rt->context, st->context) != 0)
-        return;
 
-    if (rt->charts_pattern && !simple_pattern_matches(rt->charts_pattern, st->name))
-        return;
+static char *rrdcalc_alert_name_with_dimension(const char *name, size_t namelen, const char *dim, size_t dimlen) {
+    char *newname,*move;
 
-    if (rt->family_pattern && !simple_pattern_matches(rt->family_pattern, st->family))
-        return;
+    newname = mallocz(namelen + dimlen + 2);
+    move = newname;
+    memcpy(move, name, namelen);
+    move += namelen;
 
-    if (rt->module_pattern && !simple_pattern_matches(rt->module_pattern, st->module_name))
-        return;
+    *move++ = '_';
+    memcpy(move, dim, dimlen);
+    move += dimlen;
+    *move = '\0';
+
+    return newname;
+}
+
+bool rrdcalctemplate_check_rrdset_conditions(RRDCALCTEMPLATE *rt, RRDSET *st, RRDHOST *host) {
+    if(rt->context != st->context)
+        return false;
+
+    if(rt->foreach_dimension_pattern && !rrdset_number_of_dimensions(st))
+        return false;
+
+    if (rt->charts_pattern && !simple_pattern_matches(rt->charts_pattern, rrdset_name(st)) && !simple_pattern_matches(rt->charts_pattern, rrdset_id(st)))
+        return false;
+
+    if (rt->family_pattern && !simple_pattern_matches(rt->family_pattern, rrdset_family(st)))
+        return false;
+
+    if (rt->module_pattern && !simple_pattern_matches(rt->module_pattern, rrdset_module_name(st)))
+        return false;
+
+    if (rt->plugin_pattern && !simple_pattern_matches(rt->plugin_pattern, rrdset_plugin_name(st)))
+        return false;
+
+    if(host->rrdlabels && rt->host_labels_pattern && !rrdlabels_match_simple_pattern_parsed(host->rrdlabels, rt->host_labels_pattern, '='))
+        return false;
 
-    if (rt->plugin_pattern && !simple_pattern_matches(rt->plugin_pattern, st->plugin_name))
+    return true;
+}
+
+void rrdcalctemplate_check_rrddim_conditions_and_link(RRDCALCTEMPLATE *rt, RRDSET *st, RRDDIM *rd, RRDHOST *host) {
+    if (simple_pattern_matches(rt->foreach_dimension_pattern, rrddim_id(rd)) || simple_pattern_matches(rt->foreach_dimension_pattern, rrddim_name(rd))) {
+        char *overwrite_alert_name = rrdcalc_alert_name_with_dimension(
+            rrdcalctemplate_name(rt), string_strlen(rt->name), rrddim_name(rd), string_strlen(rd->name));
+        rrdcalc_add_from_rrdcalctemplate(host, rt, st, overwrite_alert_name, rrddim_name(rd));
+        freez(overwrite_alert_name);
+    }
+}
+
+void rrdcalctemplate_check_conditions_and_link(RRDCALCTEMPLATE *rt, RRDSET *st, RRDHOST *host) {
+    if(!rrdcalctemplate_check_rrdset_conditions(rt, st, host))
         return;
 
-    if(host->host_labels && rt->host_labels_pattern && !rrdlabels_match_simple_pattern_parsed(host->host_labels, rt->host_labels_pattern, '='))
+    if(!rt->foreach_dimension_pattern) {
+        rrdcalc_add_from_rrdcalctemplate(host, rt, st, NULL, NULL);
         return;
+    }
 
-    RRDCALC *rc = rrdcalc_create_from_template(host, rt, st->id);
-    if (unlikely(!rc))
-        info("Health tried to create alarm from template '%s' on chart '%s' of host '%s', but it failed", rt->name, st->id, host->hostname);
-#ifdef NETDATA_INTERNAL_CHECKS
-    else if (rc->rrdset != st && !rc->foreachdim) //When we have a template with foreadhdim, the child will be added to the index late
-        error("Health alarm '%s.%s' should be linked to chart '%s', but it is not", rc->chart ? rc->chart : "NOCHART", rc->name, st->id);
-#endif
+    RRDDIM *rd;
+    rrddim_foreach_read(rd, st) {
+        rrdcalctemplate_check_rrddim_conditions_and_link(rt, st, rd, host);
+    }
+    rrddim_foreach_done(rd);
 }
 
-void rrdcalctemplate_link_matching(RRDSET *st) {
+void rrdcalctemplate_link_matching_templates_to_rrdset(RRDSET *st) {
     RRDHOST *host = st->rrdhost;
-    RRDCALCTEMPLATE *rt;
-
-    for(rt = host->templates; rt ; rt = rt->next)
-        rrdcalctemplate_check_conditions_and_link(rt, st, host);
 
-    for(rt = host->alarms_template_with_foreach; rt ; rt = rt->next)
+    RRDCALCTEMPLATE *rt;
+    foreach_rrdcalctemplate_read(host, rt) {
         rrdcalctemplate_check_conditions_and_link(rt, st, host);
+    }
+    foreach_rrdcalctemplate_done(rt);
 }
 
-inline void rrdcalctemplate_free(RRDCALCTEMPLATE *rt) {
-    if(unlikely(!rt)) return;
-
+static void rrdcalctemplate_free_internals(RRDCALCTEMPLATE *rt) {
     expression_free(rt->calculation);
     expression_free(rt->warning);
     expression_free(rt->critical);
 
-    freez(rt->family_match);
+    string_freez(rt->family_match);
     simple_pattern_free(rt->family_pattern);
 
-    freez(rt->plugin_match);
+    string_freez(rt->plugin_match);
     simple_pattern_free(rt->plugin_pattern);
 
-    freez(rt->module_match);
+    string_freez(rt->module_match);
     simple_pattern_free(rt->module_pattern);
 
-    freez(rt->charts_match);
+    string_freez(rt->charts_match);
     simple_pattern_free(rt->charts_pattern);
 
-    freez(rt->name);
-    freez(rt->exec);
-    freez(rt->recipient);
-    freez(rt->classification);
-    freez(rt->component);
-    freez(rt->type);
-    freez(rt->context);
-    freez(rt->source);
-    freez(rt->units);
-    freez(rt->info);
-    freez(rt->dimensions);
-    freez(rt->foreachdim);
-    freez(rt->host_labels);
-    simple_pattern_free(rt->spdim);
+    string_freez(rt->name);
+    string_freez(rt->exec);
+    string_freez(rt->recipient);
+    string_freez(rt->classification);
+    string_freez(rt->component);
+    string_freez(rt->type);
+    string_freez(rt->context);
+    string_freez(rt->source);
+    string_freez(rt->units);
+    string_freez(rt->info);
+    string_freez(rt->dimensions);
+    string_freez(rt->foreach_dimension);
+    string_freez(rt->host_labels);
+    simple_pattern_free(rt->foreach_dimension_pattern);
     simple_pattern_free(rt->host_labels_pattern);
-    freez(rt);
 }
 
-inline void rrdcalctemplate_unlink_and_free(RRDHOST *host, RRDCALCTEMPLATE *rt) {
+void rrdcalctemplate_free_unused_rrdcalctemplate_loaded_from_config(RRDCALCTEMPLATE *rt) {
     if(unlikely(!rt)) return;
 
-    debug(D_HEALTH, "Health removing template '%s' of host '%s'", rt->name, host->hostname);
+    rrdcalctemplate_free_internals(rt);
+    freez(rt);
+}
+static void rrdcalctemplate_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdcalctemplate, void *added_bool) {
+    RRDCALCTEMPLATE *rt = rrdcalctemplate; (void)rt;
+
+    bool *added = added_bool;
+    *added = true;
+
+    debug(D_HEALTH, "Health configuration adding template '%s'"
+                    ": context '%s'"
+                    ", exec '%s'"
+                    ", recipient '%s'"
+                    ", green " NETDATA_DOUBLE_FORMAT_AUTO
+                    ", red " NETDATA_DOUBLE_FORMAT_AUTO
+                    ", lookup: group %d"
+                    ", after %d"
+                    ", before %d"
+                    ", options %u"
+                    ", dimensions '%s'"
+                    ", for each dimension '%s'"
+                    ", update every %d"
+                    ", calculation '%s'"
+                    ", warning '%s'"
+                    ", critical '%s'"
+                    ", source '%s'"
+                    ", delay up %d"
+                    ", delay down %d"
+                    ", delay max %d"
+                    ", delay_multiplier %f"
+                    ", warn_repeat_every %u"
+                    ", crit_repeat_every %u",
+          rrdcalctemplate_name(rt),
+          (rt->context)?string2str(rt->context):"NONE",
+          (rt->exec)?rrdcalctemplate_exec(rt):"DEFAULT",
+          (rt->recipient)?rrdcalctemplate_recipient(rt):"DEFAULT",
+          rt->green,
+          rt->red,
+          (int)rt->group,
+          rt->after,
+          rt->before,
+          rt->options,
+          (rt->dimensions)?rrdcalctemplate_dimensions(rt):"NONE",
+          (rt->foreach_dimension)?rrdcalctemplate_foreachdim(rt):"NONE",
+          rt->update_every,
+          (rt->calculation)?rt->calculation->parsed_as:"NONE",
+          (rt->warning)?rt->warning->parsed_as:"NONE",
+          (rt->critical)?rt->critical->parsed_as:"NONE",
+          rrdcalctemplate_source(rt),
+          rt->delay_up_duration,
+          rt->delay_down_duration,
+          rt->delay_max_duration,
+          rt->delay_multiplier,
+          rt->warn_repeat_every,
+          rt->crit_repeat_every
+    );
+}
+
+static void rrdcalctemplate_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdcalctemplate, void *rrdhost __maybe_unused) {
+    RRDCALCTEMPLATE *rt = rrdcalctemplate;
+    rrdcalctemplate_free_internals(rt);
+}
+
+void rrdcalctemplate_index_init(RRDHOST *host) {
+    if(!host->rrdcalctemplate_root_index) {
+        host->rrdcalctemplate_root_index = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
 
-    if(host->templates == rt) {
-        host->templates = rt->next;
+        dictionary_register_insert_callback(host->rrdcalctemplate_root_index, rrdcalctemplate_insert_callback, NULL);
+        dictionary_register_delete_callback(host->rrdcalctemplate_root_index, rrdcalctemplate_delete_callback, host);
     }
-    else {
-        RRDCALCTEMPLATE *t;
-        for (t = host->templates; t && t->next != rt; t = t->next ) ;
-        if(t) {
-            t->next = rt->next;
-            rt->next = NULL;
-        }
-        else
-            error("Cannot find RRDCALCTEMPLATE '%s' linked in host '%s'", rt->name, host->hostname);
+}
+
+void rrdcalctemplate_index_destroy(RRDHOST *host) {
+    dictionary_destroy(host->rrdcalctemplate_root_index);
+    host->rrdcalctemplate_root_index = NULL;
+}
+
+inline void rrdcalctemplate_delete_all(RRDHOST *host) {
+    dictionary_flush(host->rrdcalctemplate_root_index);
+}
+
+#define RRDCALCTEMPLATE_MAX_KEY_SIZE 1024
+static size_t rrdcalctemplate_key(char *dst, size_t dst_len, const char *name, const char *family_match) {
+    return snprintfz(dst, dst_len, "%s/%s", name, (family_match && *family_match)?family_match:"*");
+}
+
+void rrdcalctemplate_add_from_config(RRDHOST *host, RRDCALCTEMPLATE *rt) {
+    if(unlikely(!rt->context)) {
+        error("Health configuration for template '%s' does not have a context", rrdcalctemplate_name(rt));
+        return;
+    }
+
+    if(unlikely(!rt->update_every)) {
+        error("Health configuration for template '%s' has no frequency (parameter 'every'). Ignoring it.", rrdcalctemplate_name(rt));
+        return;
     }
 
-    rrdcalctemplate_free(rt);
+    if(unlikely(!RRDCALCTEMPLATE_HAS_DB_LOOKUP(rt) && !rt->calculation && !rt->warning && !rt->critical)) {
+        error("Health configuration for template '%s' is useless (no calculation, no warning and no critical evaluation)", rrdcalctemplate_name(rt));
+        return;
+    }
+
+    char key[RRDCALCTEMPLATE_MAX_KEY_SIZE + 1];
+    size_t key_len = rrdcalctemplate_key(key, RRDCALCTEMPLATE_MAX_KEY_SIZE, rrdcalctemplate_name(rt), rrdcalctemplate_family_match(rt));
+
+    bool added = false;
+    dictionary_set_advanced(host->rrdcalctemplate_root_index, key, (ssize_t)(key_len + 1), rt, sizeof(*rt), &added);
+
+    if(added)
+        freez(rt);
+    else {
+        info("Health configuration template '%s' already exists for host '%s'.", rrdcalctemplate_name(rt), rrdhost_hostname(host));
+        rrdcalctemplate_free_unused_rrdcalctemplate_loaded_from_config(rt);
+    }
 }
diff --git a/database/rrdcalctemplate.h b/database/rrdcalctemplate.h
index 51aa33054..6212a42da 100644
--- a/database/rrdcalctemplate.h
+++ b/database/rrdcalctemplate.h
@@ -9,35 +9,34 @@
 // these are to be applied to charts found dynamically
 // based on their context.
 struct rrdcalctemplate {
-    char *name;
-    uint32_t hash_name;
     uuid_t config_hash_id;
 
-    char *exec;
-    char *recipient;
+    STRING *name;
 
-    char *classification;
-    char *component;
-    char *type;
+    STRING *exec;
+    STRING *recipient;
 
-    char *context;
-    uint32_t hash_context;
+    STRING *classification;
+    STRING *component;
+    STRING *type;
 
-    char *family_match;
+    STRING *context;
+
+    STRING *family_match;
     SIMPLE_PATTERN *family_pattern;
 
-    char *plugin_match;
+    STRING *plugin_match;
     SIMPLE_PATTERN *plugin_pattern;
 
-    char *module_match;
+    STRING *module_match;
     SIMPLE_PATTERN *module_pattern;
 
-    char *charts_match;
+    STRING *charts_match;
     SIMPLE_PATTERN *charts_pattern;
 
-    char *source;                   // the source of this alarm
-    char *units;                    // the units of the alarm
-    char *info;                     // a short description of the alarm
+    STRING *source;                 // the source of this alarm
+    STRING *units;                  // the units of the alarm
+    STRING *info;                   // a short description of the alarm
 
     int update_every;               // update frequency for the alarm
 
@@ -48,15 +47,13 @@ struct rrdcalctemplate {
     // ------------------------------------------------------------------------
     // database lookup settings
 
-    char *dimensions;               // the chart dimensions
-    char *foreachdim;               // the group of dimensions that the lookup will be applied.
-    SIMPLE_PATTERN *spdim;          // used if and only if there is a simple pattern for the chart.
-    int foreachcounter;             // the number of alarms created with foreachdim, this also works as an id of the
-                                    // children
+    STRING *dimensions;             // the chart dimensions
+    STRING *foreach_dimension;      // the group of dimensions that the lookup will be applied.
+    SIMPLE_PATTERN *foreach_dimension_pattern; // used if and only if there is a simple pattern for the chart.
     RRDR_GROUPING group;            // grouping method: average, max, etc.
     int before;                     // ending point in time-series
     int after;                      // starting point in time-series
-    uint32_t options;               // calculation options
+    RRDCALC_OPTIONS options;        // configuration options
 
     // ------------------------------------------------------------------------
     // notification delay settings
@@ -74,7 +71,7 @@ struct rrdcalctemplate {
 
     // ------------------------------------------------------------------------
     // Labels settings
-    char *host_labels;                   // the label read from an alarm file
+    STRING *host_labels;                 // the label read from an alarm file
     SIMPLE_PATTERN *host_labels_pattern; // the simple pattern of labels
 
     // ------------------------------------------------------------------------
@@ -85,13 +82,47 @@ struct rrdcalctemplate {
     EVAL_EXPRESSION *critical;
 
     struct rrdcalctemplate *next;
+    struct rrdcalctemplate *prev;
 };
 
+#define foreach_rrdcalctemplate_read(host, rt) \
+    dfe_start_read((host)->rrdcalctemplate_root_index, rt)
+
+#define foreach_rrdcalctemplate_done(rt) \
+    dfe_done(rt)
+
+#define rrdcalctemplate_name(rt) string2str((rt)->name)
+#define rrdcalctemplate_exec(rt) string2str((rt)->exec)
+#define rrdcalctemplate_recipient(rt) string2str((rt)->recipient)
+#define rrdcalctemplate_classification(rt) string2str((rt)->classification)
+#define rrdcalctemplate_component(rt) string2str((rt)->component)
+#define rrdcalctemplate_type(rt) string2str((rt)->type)
+#define rrdcalctemplate_family_match(rt) string2str((rt)->family_match)
+#define rrdcalctemplate_plugin_match(rt) string2str((rt)->plugin_match)
+#define rrdcalctemplate_module_match(rt) string2str((rt)->module_match)
+#define rrdcalctemplate_charts_match(rt) string2str((rt)->charts_match)
+#define rrdcalctemplate_units(rt) string2str((rt)->units)
+#define rrdcalctemplate_info(rt) string2str((rt)->info)
+#define rrdcalctemplate_source(rt) string2str((rt)->source)
+#define rrdcalctemplate_dimensions(rt) string2str((rt)->dimensions)
+#define rrdcalctemplate_foreachdim(rt) string2str((rt)->foreach_dimension)
+#define rrdcalctemplate_host_labels(rt) string2str((rt)->host_labels)
+
 #define RRDCALCTEMPLATE_HAS_DB_LOOKUP(rt) ((rt)->after)
 
-extern void rrdcalctemplate_link_matching(RRDSET *st);
+void rrdcalctemplate_link_matching_templates_to_rrdset(RRDSET *st);
+
+void rrdcalctemplate_free_unused_rrdcalctemplate_loaded_from_config(RRDCALCTEMPLATE *rt);
+void rrdcalctemplate_delete_all(RRDHOST *host);
+void rrdcalctemplate_add_from_config(RRDHOST *host, RRDCALCTEMPLATE *rt);
+
+void rrdcalctemplate_check_conditions_and_link(RRDCALCTEMPLATE *rt, RRDSET *st, RRDHOST *host);
+
+bool rrdcalctemplate_check_rrdset_conditions(RRDCALCTEMPLATE *rt, RRDSET *st, RRDHOST *host);
+void rrdcalctemplate_check_rrddim_conditions_and_link(RRDCALCTEMPLATE *rt, RRDSET *st, RRDDIM *rd, RRDHOST *host);
+
+
+void rrdcalctemplate_index_init(RRDHOST *host);
+void rrdcalctemplate_index_destroy(RRDHOST *host);
 
-extern void rrdcalctemplate_free(RRDCALCTEMPLATE *rt);
-extern void rrdcalctemplate_unlink_and_free(RRDHOST *host, RRDCALCTEMPLATE *rt);
-extern void rrdcalctemplate_create_alarms(RRDHOST *host, RRDCALCTEMPLATE *rt, RRDSET *st);
 #endif //NETDATA_RRDCALCTEMPLATE_H
diff --git a/database/rrdcontext.c b/database/rrdcontext.c
index 24884dbc0..cfa8af3e0 100644
--- a/database/rrdcontext.c
+++ b/database/rrdcontext.c
@@ -4,17 +4,30 @@
 #include "sqlite/sqlite_context.h"
 #include "aclk/schema-wrappers/context.h"
 #include "aclk/aclk_contexts_api.h"
-#include "aclk/aclk_api.h"
-
-int rrdcontext_enabled = CONFIG_BOOLEAN_YES;
+#include "aclk/aclk.h"
+#include "storage_engine.h"
 
 #define MESSAGES_PER_BUNDLE_TO_SEND_TO_HUB_PER_HOST         5000
 #define FULL_RETENTION_SCAN_DELAY_AFTER_DB_ROTATION_SECS    120
-#define RRDCONTEXT_WORKER_THREAD_HEARTBEAT_SECS             1
+#define RRDCONTEXT_WORKER_THREAD_HEARTBEAT_USEC             (1000 * USEC_PER_MS)
 #define RRDCONTEXT_MINIMUM_ALLOWED_PRIORITY                 10
 
-// #define LOG_TRANSITIONS 1
-// #define LOG_RRDINSTANCES 1
+#define LOG_TRANSITIONS false
+
+#define WORKER_JOB_HOSTS            1
+#define WORKER_JOB_CHECK            2
+#define WORKER_JOB_SEND             3
+#define WORKER_JOB_DEQUEUE          4
+#define WORKER_JOB_RETENTION        5
+#define WORKER_JOB_QUEUED           6
+#define WORKER_JOB_CLEANUP          7
+#define WORKER_JOB_CLEANUP_DELETE   8
+#define WORKER_JOB_PP_METRIC        9 // post-processing metrics
+#define WORKER_JOB_PP_INSTANCE     10 // post-processing instances
+#define WORKER_JOB_PP_CONTEXT      11 // post-processing contexts
+#define WORKER_JOB_HUB_QUEUE_SIZE  12
+#define WORKER_JOB_PP_QUEUE_SIZE   13
+
 
 typedef enum {
     RRD_FLAG_NONE           = 0,
@@ -24,46 +37,36 @@ typedef enum {
     RRD_FLAG_ARCHIVED       = (1 << 3), // this object is not currently being collected
     RRD_FLAG_OWN_LABELS     = (1 << 4), // this instance has its own labels - not linked to an RRDSET
     RRD_FLAG_LIVE_RETENTION = (1 << 5), // we have got live retention from the database
-    RRD_FLAG_QUEUED         = (1 << 6), // this context is currently queued to be dispatched to hub
-    RRD_FLAG_DONT_PROCESS   = (1 << 7), // don't process updates for this object
+    RRD_FLAG_QUEUED_FOR_HUB = (1 << 6), // this context is currently queued to be dispatched to hub
+    RRD_FLAG_QUEUED_FOR_PP  = (1 << 7), // this context is currently queued to be post-processed
     RRD_FLAG_HIDDEN         = (1 << 8), // don't expose this to the hub or the API
 
+    RRD_FLAG_UPDATE_REASON_TRIGGERED               = (1 << 9),  // the update was triggered by the child object
     RRD_FLAG_UPDATE_REASON_LOAD_SQL                = (1 << 10), // this object has just been loaded from SQL
     RRD_FLAG_UPDATE_REASON_NEW_OBJECT              = (1 << 11), // this object has just been created
     RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT          = (1 << 12), // we received an update on this object
     RRD_FLAG_UPDATE_REASON_CHANGED_LINKING         = (1 << 13), // an instance or a metric switched RRDSET or RRDDIM
-    RRD_FLAG_UPDATE_REASON_CHANGED_UUID            = (1 << 14), // an instance or a metric changed UUID
-    RRD_FLAG_UPDATE_REASON_CHANGED_NAME            = (1 << 15), // an instance or a metric changed name
-    RRD_FLAG_UPDATE_REASON_CHANGED_UNITS           = (1 << 16), // this context or instance changed units
-    RRD_FLAG_UPDATE_REASON_CHANGED_TITLE           = (1 << 17), // this context or instance changed title
-    RRD_FLAG_UPDATE_REASON_CHANGED_FAMILY          = (1 << 18), // the context or the instance changed family
-    RRD_FLAG_UPDATE_REASON_CHANGED_CHART_TYPE      = (1 << 19), // this context or instance changed chart type
-    RRD_FLAG_UPDATE_REASON_CHANGED_PRIORITY        = (1 << 20), // this context or instance changed its priority
-    RRD_FLAG_UPDATE_REASON_CHANGED_UPDATE_EVERY    = (1 << 21), // the instance or the metric changed update frequency
-    RRD_FLAG_UPDATE_REASON_ZERO_RETENTION          = (1 << 22), // this object has not retention
-    RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T    = (1 << 23), // this object changed its oldest time in the db
-    RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T     = (1 << 24), // this object change its latest time in the db
-    RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED = (1 << 25), // this object has stopped being collected
-    RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED = (1 << 26), // this object has started being collected
-    RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD      = (1 << 27), // this context belongs to a host that just disconnected
-    RRD_FLAG_UPDATE_REASON_DB_ROTATION             = (1 << 28), // this context changed because of a db rotation
-    RRD_FLAG_UPDATE_REASON_UNUSED                  = (1 << 29), // this context is not used anymore
-    RRD_FLAG_UPDATE_REASON_CHANGED_FLAGS           = (1 << 30), // this context is not used anymore
+    RRD_FLAG_UPDATE_REASON_CHANGED_METADATA        = (1 << 14), // this context or instance changed uuid, name, units, title, family, chart type, priority, update every, rrd changed flags
+    RRD_FLAG_UPDATE_REASON_ZERO_RETENTION          = (1 << 15), // this object has no retention
+    RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T    = (1 << 16), // this object changed its oldest time in the db
+    RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T     = (1 << 17), // this object change its latest time in the db
+    RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED = (1 << 18), // this object has stopped being collected
+    RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED = (1 << 19), // this object has started being collected
+    RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD      = (1 << 20), // this context belongs to a host that just disconnected
+    RRD_FLAG_UPDATE_REASON_UNUSED                  = (1 << 21), // this context is not used anymore
+    RRD_FLAG_UPDATE_REASON_DB_ROTATION             = (1 << 22), // this context changed because of a db rotation
+
+    // action to perform on an object
+    RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION        = (1 << 30), // this object has to update its retention from the db
 } RRD_FLAGS;
 
 #define RRD_FLAG_ALL_UPDATE_REASONS                   ( \
-     RRD_FLAG_UPDATE_REASON_LOAD_SQL                    \
+     RRD_FLAG_UPDATE_REASON_TRIGGERED                   \
+    |RRD_FLAG_UPDATE_REASON_LOAD_SQL                    \
     |RRD_FLAG_UPDATE_REASON_NEW_OBJECT                  \
     |RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT              \
     |RRD_FLAG_UPDATE_REASON_CHANGED_LINKING             \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_UUID                \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_NAME                \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_UNITS               \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_TITLE               \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_FAMILY              \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_CHART_TYPE          \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_PRIORITY            \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_UPDATE_EVERY        \
+    |RRD_FLAG_UPDATE_REASON_CHANGED_METADATA            \
     |RRD_FLAG_UPDATE_REASON_ZERO_RETENTION              \
     |RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T        \
     |RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T         \
@@ -72,60 +75,113 @@ typedef enum {
     |RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD          \
     |RRD_FLAG_UPDATE_REASON_DB_ROTATION                 \
     |RRD_FLAG_UPDATE_REASON_UNUSED                      \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_FLAGS               \
  )
 
 #define RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS   ( \
      RRD_FLAG_ARCHIVED                                  \
-    |RRD_FLAG_DONT_PROCESS                              \
     |RRD_FLAG_HIDDEN                                    \
     |RRD_FLAG_ALL_UPDATE_REASONS                        \
  )
 
+#define RRD_FLAGS_REQUIRED_FOR_DELETIONS              ( \
+     RRD_FLAG_DELETED                                   \
+    |RRD_FLAG_LIVE_RETENTION                            \
+)
+
 #define RRD_FLAGS_PREVENTING_DELETIONS                ( \
-     RRD_FLAG_QUEUED                                    \
+     RRD_FLAG_QUEUED_FOR_HUB                            \
     |RRD_FLAG_COLLECTED                                 \
-    |RRD_FLAG_UPDATE_REASON_LOAD_SQL                    \
-    |RRD_FLAG_UPDATE_REASON_NEW_OBJECT                  \
-    |RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT              \
-    |RRD_FLAG_UPDATE_REASON_CHANGED_LINKING             \
+    |RRD_FLAG_QUEUED_FOR_PP                             \
 )
 
-#define rrd_flag_set_updated(obj, reason) (obj)->flags |=  (RRD_FLAG_UPDATED | (reason))
-#define rrd_flag_unset_updated(obj)       (obj)->flags &= ~(RRD_FLAG_UPDATED | RRD_FLAG_ALL_UPDATE_REASONS)
-
-#define rrd_flag_set_collected(obj)                                                                        do { \
-        if(likely( !((obj)->flags &    RRD_FLAG_COLLECTED)))                                                    \
-                     (obj)->flags |=  (RRD_FLAG_COLLECTED | RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED | RRD_FLAG_UPDATED); \
-        if(likely(  ((obj)->flags &   (RRD_FLAG_ARCHIVED  | RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED))))  \
-                     (obj)->flags &= ~(RRD_FLAG_ARCHIVED  | RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED);    \
-        if(unlikely(((obj)->flags &   (RRD_FLAG_DELETED   | RRD_FLAG_UPDATE_REASON_ZERO_RETENTION))))           \
-                     (obj)->flags &= ~(RRD_FLAG_DELETED   | RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);             \
-        if(unlikely(((obj)->flags &    RRD_FLAG_DONT_PROCESS)))                                                 \
-                     (obj)->flags &=  ~RRD_FLAG_DONT_PROCESS;                                                   \
-} while(0)
-
-#define rrd_flag_set_archived(obj)                                                                         do { \
-        if(likely( !((obj)->flags &    RRD_FLAG_ARCHIVED)))                                                     \
-                     (obj)->flags |=  (RRD_FLAG_ARCHIVED  | RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED | RRD_FLAG_UPDATED); \
-        if(likely(  ((obj)->flags &   (RRD_FLAG_COLLECTED | RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED))))  \
-                     (obj)->flags &= ~(RRD_FLAG_COLLECTED | RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED);    \
-        if(unlikely(((obj)->flags &   (RRD_FLAG_DELETED   | RRD_FLAG_UPDATE_REASON_ZERO_RETENTION))))           \
-                     (obj)->flags &= ~(RRD_FLAG_DELETED   | RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);             \
-} while(0)
-
-#define rrd_flag_set_deleted(obj, reason)                                                                  do { \
-        if(likely( !((obj)->flags &    RRD_FLAG_DELETED)))                                                      \
-                     (obj)->flags |=  (RRD_FLAG_DELETED | RRD_FLAG_UPDATE_REASON_ZERO_RETENTION | RRD_FLAG_UPDATED | (reason)); \
-        if(unlikely(((obj)->flags &    RRD_FLAG_ARCHIVED)))                                                     \
-                     (obj)->flags &=  ~RRD_FLAG_ARCHIVED;                                                       \
-        if(likely(  ((obj)->flags &    RRD_FLAG_COLLECTED)))                                                    \
-                     (obj)->flags &=  ~RRD_FLAG_COLLECTED;                                                      \
-} while(0)
-
-
-#define rrd_flag_is_collected(obj) ((obj)->flags & RRD_FLAG_COLLECTED)
-#define rrd_flag_is_archived(obj) ((obj)->flags & RRD_FLAG_ARCHIVED)
+// get all the flags of an object
+#define rrd_flags_get(obj) __atomic_load_n(&((obj)->flags), __ATOMIC_SEQ_CST)
+
+// check if ANY of the given flags (bits) is set
+#define rrd_flag_check(obj, flag) (rrd_flags_get(obj) & (flag))
+
+// check if ALL the given flags (bits) are set
+#define rrd_flag_check_all(obj, flag) (rrd_flag_check(obj, flag) == (flag))
+
+// set one or more flags (bits)
+#define rrd_flag_set(obj, flag)   __atomic_or_fetch(&((obj)->flags), flag, __ATOMIC_SEQ_CST)
+
+// clear one or more flags (bits)
+#define rrd_flag_clear(obj, flag) __atomic_and_fetch(&((obj)->flags), ~(flag), __ATOMIC_SEQ_CST)
+
+// replace the flags of an object, with the supplied ones
+#define rrd_flags_replace(obj, all_flags) __atomic_store_n(&((obj)->flags), all_flags, __ATOMIC_SEQ_CST)
+
+static inline void
+rrd_flag_add_remove_atomic(RRD_FLAGS *flags, RRD_FLAGS check, RRD_FLAGS conditionally_add, RRD_FLAGS always_remove) {
+    RRD_FLAGS expected, desired;
+    do {
+        expected = *flags;
+
+        desired = expected;
+        desired &= ~(always_remove);
+
+        if(!(expected & check))
+            desired |= (check | conditionally_add);
+
+    } while(!__atomic_compare_exchange_n(flags, &expected, desired, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST));
+}
+
+#define rrd_flag_set_collected(obj)                                                                             \
+        rrd_flag_add_remove_atomic(&((obj)->flags)                                                              \
+                               /* check this flag */                                                            \
+                               , RRD_FLAG_COLLECTED                                                             \
+                                                                                                                \
+                               /* add these flags together with the above, if the above is not already set */   \
+                               , RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED | RRD_FLAG_UPDATED              \
+                                                                                                                \
+                               /* always remove these flags */                                                  \
+                               , RRD_FLAG_ARCHIVED                                                              \
+                               | RRD_FLAG_DELETED                                                               \
+                               | RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED                                 \
+                               | RRD_FLAG_UPDATE_REASON_ZERO_RETENTION                                          \
+                               | RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD                                      \
+        )
+
+#define rrd_flag_set_archived(obj)                                                                              \
+        rrd_flag_add_remove_atomic(&((obj)->flags)                                                              \
+                               /* check this flag */                                                            \
+                               , RRD_FLAG_ARCHIVED                                                              \
+                                                                                                                \
+                               /* add these flags together with the above, if the above is not already set */   \
+                               , RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED | RRD_FLAG_UPDATED              \
+                                                                                                                \
+                               /* always remove these flags */                                                  \
+                               , RRD_FLAG_COLLECTED                                                             \
+                               | RRD_FLAG_DELETED                                                               \
+                               | RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED                                 \
+                               | RRD_FLAG_UPDATE_REASON_ZERO_RETENTION                                          \
+        )
+
+#define rrd_flag_set_deleted(obj, reason)                                                                       \
+        rrd_flag_add_remove_atomic(&((obj)->flags)                                                              \
+                               /* check this flag */                                                            \
+                               , RRD_FLAG_DELETED                                                               \
+                                                                                                                \
+                               /* add these flags together with the above, if the above is not already set */   \
+                               , RRD_FLAG_UPDATE_REASON_ZERO_RETENTION | RRD_FLAG_UPDATED | (reason)            \
+                                                                                                                \
+                               /* always remove these flags */                                                  \
+                               , RRD_FLAG_ARCHIVED                                                              \
+                               | RRD_FLAG_COLLECTED                                                             \
+        )
+
+#define rrd_flag_is_collected(obj) rrd_flag_check(obj, RRD_FLAG_COLLECTED)
+#define rrd_flag_is_archived(obj) rrd_flag_check(obj, RRD_FLAG_ARCHIVED)
+#define rrd_flag_is_deleted(obj) rrd_flag_check(obj, RRD_FLAG_DELETED)
+#define rrd_flag_is_updated(obj) rrd_flag_check(obj, RRD_FLAG_UPDATED)
+
+// mark an object as updated, providing reasons (additional bits)
+#define rrd_flag_set_updated(obj, reason) rrd_flag_set(obj,  RRD_FLAG_UPDATED | (reason))
+
+// clear an object as being updated, clearing also all the reasons
+#define rrd_flag_unset_updated(obj)       rrd_flag_clear(obj, RRD_FLAG_UPDATED | RRD_FLAG_ALL_UPDATE_REASONS)
+
 
 static struct rrdcontext_reason {
     RRD_FLAGS flag;
@@ -133,32 +189,26 @@ static struct rrdcontext_reason {
     usec_t delay_ut;
 } rrdcontext_reasons[] = {
     // context related
-    { RRD_FLAG_UPDATE_REASON_NEW_OBJECT,              "object created",       60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT,          "object updated",       60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_LOAD_SQL,                "loaded from sql",      60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_TITLE,           "changed title",        30 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_UNITS,           "changed units",        30 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_FAMILY,          "changed family",       30 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_PRIORITY,        "changed priority",     30 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_ZERO_RETENTION,          "has no retention",     60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T,    "updated first_time_t", 30 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T,     "updated last_time_t",  60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_CHART_TYPE,      "changed chart type",   30 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED, "stopped collected",    60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED, "started collected",    0 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_UNUSED,                  "unused",               0 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_TRIGGERED,               "triggered transition", 65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_NEW_OBJECT,              "object created",       65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT,          "object updated",       65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_LOAD_SQL,                "loaded from sql",      65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_CHANGED_METADATA,        "changed metadata",     65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_ZERO_RETENTION,          "has no retention",     65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T,    "updated first_time_t", 65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T,     "updated last_time_t",  65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_STOPPED_BEING_COLLECTED, "stopped collected",    65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_STARTED_BEING_COLLECTED, "started collected",    5 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_UNUSED,                  "unused",               5 * USEC_PER_SEC },
 
     // not context related
-    { RRD_FLAG_UPDATE_REASON_CHANGED_UUID,            "changed uuid",         60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_UPDATE_EVERY,    "changed updated every",60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_LINKING,         "changed rrd link",     60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_NAME,            "changed name",         60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD,      "child disconnected",   30 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_DB_ROTATION,             "db rotation",          60 * USEC_PER_SEC },
-    { RRD_FLAG_UPDATE_REASON_CHANGED_FLAGS,           "changed flags",        60 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_CHANGED_LINKING,         "changed rrd link",     65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD,      "child disconnected",   65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_DB_ROTATION,             "db rotation",          65 * USEC_PER_SEC },
+    {RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION,        "updated retention",    65 * USEC_PER_SEC },
 
     // terminator
-    { 0, NULL, 0 },
+    {0, NULL,                                                                0 },
 };
 
 
@@ -175,8 +225,6 @@ typedef struct rrdmetric {
     RRD_FLAGS flags;
 
     struct rrdinstance *ri;
-
-    usec_t created_ut;                  // the time this object was created
 } RRDMETRIC;
 
 typedef struct rrdinstance {
@@ -197,10 +245,16 @@ typedef struct rrdinstance {
     int update_every;                   // data collection frequency
     RRDSET *rrdset;                     // pointer to RRDSET when collected, or NULL
 
-    DICTIONARY *rrdlabels;              // linked to RRDSET->state->chart_labels or own version
+    DICTIONARY *rrdlabels;              // linked to RRDSET->chart_labels or own version
 
     struct rrdcontext *rc;
     DICTIONARY *rrdmetrics;
+
+    struct {
+        uint32_t collected_metrics_count;   // a temporary variable to detect BEGIN/END without SET
+                                            // don't use it for other purposes
+                                            // it goes up and then resets to zero, on every iteration
+    } internal;
 } RRDINSTANCE;
 
 typedef struct rrdcontext {
@@ -223,11 +277,19 @@ typedef struct rrdcontext {
     RRDHOST *rrdhost;
 
     struct {
+        RRD_FLAGS queued_flags;         // the last flags that triggered the post-processing
+        usec_t queued_ut;               // the last time this was queued
+        usec_t dequeued_ut;             // the last time we sent (or deduplicated) this context
+        size_t executions;              // how many times this context has been processed
+    } pp;
+
+    struct {
         RRD_FLAGS queued_flags;         // the last flags that triggered the queueing
         usec_t queued_ut;               // the last time this was queued
         usec_t delay_calc_ut;           // the last time we calculated the scheduled_dispatched_ut
         usec_t scheduled_dispatch_ut;   // the time it was/is scheduled to be sent
-        usec_t dequeued_ut;             // the last time we sent (or deduped) this context
+        usec_t dequeued_ut;             // the last time we sent (or deduplicated) this context
+        size_t dispatches;              // the number of times this has been dispatched to hub
     } queue;
 
     netdata_mutex_t mutex;
@@ -236,28 +298,51 @@ typedef struct rrdcontext {
 // ----------------------------------------------------------------------------
 // helper one-liners for RRDMETRIC
 
+static bool rrdmetric_update_retention(RRDMETRIC *rm);
+
 static inline RRDMETRIC *rrdmetric_acquired_value(RRDMETRIC_ACQUIRED *rma) {
     return dictionary_acquired_item_value((DICTIONARY_ITEM *)rma);
 }
 
+static inline RRDMETRIC_ACQUIRED *rrdmetric_acquired_dup(RRDMETRIC_ACQUIRED *rma) {
+    RRDMETRIC *rm = rrdmetric_acquired_value(rma);
+    return (RRDMETRIC_ACQUIRED *)dictionary_acquired_item_dup(rm->ri->rrdmetrics, (DICTIONARY_ITEM *)rma);
+}
+
 static inline void rrdmetric_release(RRDMETRIC_ACQUIRED *rma) {
     RRDMETRIC *rm = rrdmetric_acquired_value(rma);
     dictionary_acquired_item_release(rm->ri->rrdmetrics, (DICTIONARY_ITEM *)rma);
 }
 
-// ----------------------------------------------------------------------------
-// helper one-liners for RRDINSTANCE
+const char *rrdmetric_acquired_id(RRDMETRIC_ACQUIRED *rma) {
+    RRDMETRIC *rm = rrdmetric_acquired_value(rma);
+    return string2str(rm->id);
+}
+
+const char *rrdmetric_acquired_name(RRDMETRIC_ACQUIRED *rma) {
+    RRDMETRIC *rm = rrdmetric_acquired_value(rma);
+    return string2str(rm->name);
+}
 
-static inline RRDINSTANCE_ACQUIRED *rrdinstance_dup(RRDINSTANCE_ACQUIRED *ria) {
-    return (RRDINSTANCE_ACQUIRED *)dictionary_acquired_item_dup((DICTIONARY_ITEM *)ria);
+NETDATA_DOUBLE rrdmetric_acquired_last_stored_value(RRDMETRIC_ACQUIRED *rma) {
+    RRDMETRIC *rm = rrdmetric_acquired_value(rma);
+
+    if(rm->rrddim)
+        return rm->rrddim->last_stored_value;
+
+    return NAN;
 }
 
+// ----------------------------------------------------------------------------
+// helper one-liners for RRDINSTANCE
+
 static inline RRDINSTANCE *rrdinstance_acquired_value(RRDINSTANCE_ACQUIRED *ria) {
     return dictionary_acquired_item_value((DICTIONARY_ITEM *)ria);
 }
 
-static inline const char *rrdinstance_acquired_name(RRDINSTANCE_ACQUIRED *ria) {
-    return dictionary_acquired_item_name((DICTIONARY_ITEM *)ria);
+static inline RRDINSTANCE_ACQUIRED *rrdinstance_acquired_dup(RRDINSTANCE_ACQUIRED *ria) {
+    RRDINSTANCE *ri = rrdinstance_acquired_value(ria);
+    return (RRDINSTANCE_ACQUIRED *)dictionary_acquired_item_dup(ri->rc->rrdinstances, (DICTIONARY_ITEM *)ria);
 }
 
 static inline void rrdinstance_release(RRDINSTANCE_ACQUIRED *ria) {
@@ -265,23 +350,42 @@ static inline void rrdinstance_release(RRDINSTANCE_ACQUIRED *ria) {
     dictionary_acquired_item_release(ri->rc->rrdinstances, (DICTIONARY_ITEM *)ria);
 }
 
-// ----------------------------------------------------------------------------
-// helper one-liners for RRDCONTEXT
+const char *rrdinstance_acquired_id(RRDINSTANCE_ACQUIRED *ria) {
+    RRDINSTANCE *ri = rrdinstance_acquired_value(ria);
+    return string2str(ri->id);
+}
+
+const char *rrdinstance_acquired_name(RRDINSTANCE_ACQUIRED *ria) {
+    RRDINSTANCE *ri = rrdinstance_acquired_value(ria);
+    return string2str(ri->name);
+}
 
-static inline RRDCONTEXT_ACQUIRED *rrdcontext_dup(RRDCONTEXT_ACQUIRED *rca) {
-    return (RRDCONTEXT_ACQUIRED *)dictionary_acquired_item_dup((DICTIONARY_ITEM *)rca);
+DICTIONARY *rrdinstance_acquired_labels(RRDINSTANCE_ACQUIRED *ria) {
+    RRDINSTANCE *ri = rrdinstance_acquired_value(ria);
+    return ri->rrdlabels;
 }
 
-static inline const char *rrdcontext_acquired_name(RRDCONTEXT_ACQUIRED *rca) {
-    return dictionary_acquired_item_name((DICTIONARY_ITEM *)rca);
+DICTIONARY *rrdinstance_acquired_functions(RRDINSTANCE_ACQUIRED *ria) {
+    RRDINSTANCE *ri = rrdinstance_acquired_value(ria);
+    if(!ri->rrdset) return NULL;
+    return ri->rrdset->functions_view;
 }
 
+// ----------------------------------------------------------------------------
+// helper one-liners for RRDCONTEXT
+
 static inline RRDCONTEXT *rrdcontext_acquired_value(RRDCONTEXT_ACQUIRED *rca) {
     return dictionary_acquired_item_value((DICTIONARY_ITEM *)rca);
 }
 
-static inline RRDCONTEXT_ACQUIRED *rrdcontext_acquire(RRDHOST *host, const char *name) {
-    return (RRDCONTEXT_ACQUIRED *)dictionary_get_and_acquire_item((DICTIONARY *)host->rrdctx, name);
+const char *rrdcontext_acquired_id(RRDCONTEXT_ACQUIRED *rca) {
+    RRDCONTEXT *rc = rrdcontext_acquired_value(rca);
+    return string2str(rc->id);
+}
+
+static inline RRDCONTEXT_ACQUIRED *rrdcontext_acquired_dup(RRDCONTEXT_ACQUIRED *rca) {
+    RRDCONTEXT *rc = rrdcontext_acquired_value(rca);
+    return (RRDCONTEXT_ACQUIRED *)dictionary_acquired_item_dup((DICTIONARY *)rc->rrdhost->rrdctx, (DICTIONARY_ITEM *)rca);
 }
 
 static inline void rrdcontext_release(RRDCONTEXT_ACQUIRED *rca) {
@@ -289,29 +393,40 @@ static inline void rrdcontext_release(RRDCONTEXT_ACQUIRED *rca) {
     dictionary_acquired_item_release((DICTIONARY *)rc->rrdhost->rrdctx, (DICTIONARY_ITEM *)rca);
 }
 
-static void rrdcontext_recalculate_context_retention(RRDCONTEXT *rc, RRD_FLAGS reason, int job_id);
-static void rrdcontext_recalculate_host_retention(RRDHOST *host, RRD_FLAGS reason, int job_id);
+static void rrdcontext_recalculate_context_retention(RRDCONTEXT *rc, RRD_FLAGS reason, bool worker_jobs);
+static void rrdcontext_recalculate_host_retention(RRDHOST *host, RRD_FLAGS reason, bool worker_jobs);
 
 #define rrdcontext_version_hash(host) rrdcontext_version_hash_with_callback(host, NULL, false, NULL)
 static uint64_t rrdcontext_version_hash_with_callback(RRDHOST *host, void (*callback)(RRDCONTEXT *, bool, void *), bool snapshot, void *bundle);
 
-void rrdcontext_delete_from_sql_unsafe(RRDCONTEXT *rc);
+static void rrdcontext_garbage_collect_single_host(RRDHOST *host, bool worker_jobs);
+static void rrdcontext_garbage_collect_for_all_hosts(void);
 
 #define rrdcontext_lock(rc) netdata_mutex_lock(&((rc)->mutex))
 #define rrdcontext_unlock(rc) netdata_mutex_unlock(&((rc)->mutex))
 
 // ----------------------------------------------------------------------------
-// Updates triggers
+// Forward definitions
+
+static uint64_t rrdcontext_get_next_version(RRDCONTEXT *rc);
+static bool check_if_cloud_version_changed_unsafe(RRDCONTEXT *rc, bool sending __maybe_unused);
+static void rrdcontext_message_send_unsafe(RRDCONTEXT *rc, bool snapshot __maybe_unused, void *bundle __maybe_unused);
 
-static void rrdmetric_trigger_updates(RRDMETRIC *rm, bool force, bool escalate);
-static void rrdinstance_trigger_updates(RRDINSTANCE *ri, bool force, bool escalate);
-static void rrdcontext_trigger_updates(RRDCONTEXT *rc, bool force);
+static void rrdcontext_delete_from_sql_unsafe(RRDCONTEXT *rc);
+
+static void rrdcontext_dequeue_from_post_processing(RRDCONTEXT *rc);
+static void rrdcontext_queue_for_post_processing(RRDCONTEXT *rc, const char *function, RRD_FLAGS flags);
+static void rrdcontext_post_process_updates(RRDCONTEXT *rc, bool force, RRD_FLAGS reason, bool worker_jobs);
+
+static void rrdmetric_trigger_updates(RRDMETRIC *rm, const char *function);
+static void rrdinstance_trigger_updates(RRDINSTANCE *ri, const char *function);
+static void rrdcontext_trigger_updates(RRDCONTEXT *rc, const char *function);
 
 // ----------------------------------------------------------------------------
 // visualizing flags
 
 static void rrd_flags_to_buffer(RRD_FLAGS flags, BUFFER *wb) {
-    if(flags & RRD_FLAG_QUEUED)
+    if(flags & RRD_FLAG_QUEUED_FOR_HUB)
         buffer_strcat(wb, "QUEUED ");
 
     if(flags & RRD_FLAG_DELETED)
@@ -332,11 +447,11 @@ static void rrd_flags_to_buffer(RRD_FLAGS flags, BUFFER *wb) {
     if(flags & RRD_FLAG_LIVE_RETENTION)
         buffer_strcat(wb, "LIVE_RETENTION ");
 
-    if(flags & RRD_FLAG_DONT_PROCESS)
-        buffer_strcat(wb, "DONT_PROCESS ");
-
     if(flags & RRD_FLAG_HIDDEN)
         buffer_strcat(wb, "HIDDEN ");
+
+    if(flags & RRD_FLAG_QUEUED_FOR_PP)
+        buffer_strcat(wb, "PENDING_UPDATES ");
 }
 
 static void rrd_reasons_to_buffer(RRD_FLAGS flags, BUFFER *wb) {
@@ -351,117 +466,10 @@ static void rrd_reasons_to_buffer(RRD_FLAGS flags, BUFFER *wb) {
 }
 
 // ----------------------------------------------------------------------------
-// logging of all data collected
-
-#ifdef LOG_TRANSITIONS
-static void log_transition(STRING *metric, STRING *instance, STRING *context, RRD_FLAGS flags, const char *msg) {
-    BUFFER *wb = buffer_create(1000);
-
-    buffer_sprintf(wb, "RRD TRANSITION: context '%s'", string2str(context));
-
-    if(instance)
-        buffer_sprintf(wb, ", instance '%s'", string2str(instance));
-
-    if(metric)
-        buffer_sprintf(wb, ", metric '%s'", string2str(metric));
-
-    buffer_sprintf(wb, ", triggered by %s: ", msg);
-
-    rrd_flags_to_buffer(flags, wb);
-
-    buffer_strcat(wb, ", reasons: ");
-
-    rrd_reasons_to_buffer(flags, wb);
-
-    internal_error(true, "%s", buffer_tostring(wb));
-    buffer_free(wb);
-}
-#else
-#define log_transition(metric, instance, context, flags, msg) debug_dummy()
-#endif
-
-#ifdef LOG_RRDINSTANCES
-static void rrdinstance_log(RRDINSTANCE *ri, const char *msg) {
-    char uuid[UUID_STR_LEN];
-
-    uuid_unparse(ri->uuid, uuid);
-
-    BUFFER *wb = buffer_create(1000);
-
-    buffer_sprintf(wb,
-                   "RRDINSTANCE: %s id '%s' (host '%s'), uuid '%s', name '%s', context '%s', title '%s', units '%s', family '%s', priority %zu, chart type '%s', update every %d, rrdset '%s', flags %s%s%s%s%s%s%s%s, first_time_t %ld, last_time_t %ld",
-                   msg,
-                   string2str(ri->id),
-                   ri->rc->rrdhost->hostname,
-                   uuid,
-                   string2str(ri->name),
-                   string2str(ri->rc->id),
-                   string2str(ri->title),
-                   string2str(ri->units),
-                   string2str(ri->family),
-                   ri->priority,
-                   rrdset_type_name(ri->chart_type),
-                   ri->update_every,
-                   ri->rrdset?ri->rrdset->id:"NONE",
-                   ri->flags & RRD_FLAG_DELETED ?"DELETED ":"",
-                   ri->flags & RRD_FLAG_UPDATED ?"UPDATED ":"",
-                   rrd_flag_is_collected(ri) ?"COLLECTED ":"",
-                   rrd_flag_is_archived(ri) ?"ARCHIVED ":"",
-                   ri->flags & RRD_FLAG_OWNLABELS ?"OWNLABELS ":"",
-                   ri->flags & RRD_FLAG_LIVE_RETENTION ?"LIVE ":"",
-                   ri->flags & RRD_FLAG_QUEUED ?"QUEUED ":"",
-                   ri->flags & RRD_FLAG_DONT_TRIGGER ?"BLOCKED ":"",
-                   ri->first_time_t,
-                   ri->last_time_t
-                   );
-
-    buffer_strcat(wb, ", update reasons: { ");
-    for(int i = 0, added = 0; rrdcontext_reasons[i].name ;i++)
-        if(ri->flags & rrdcontext_reasons[i].flag) {
-            if(added) buffer_strcat(wb, ", ");
-            buffer_strcat(wb, rrdcontext_reasons[i].name);
-            added++;
-        }
-    buffer_strcat(wb, " }");
-
-    buffer_strcat(wb, ", labels: { ");
-    if(ri->rrdlabels) {
-        if(!rrdlabels_to_buffer(ri->rrdlabels, wb, "", "=", "'", ", ", NULL, NULL, NULL, NULL))
-            buffer_strcat(wb, "EMPTY }");
-        else
-            buffer_strcat(wb, " }");
-    }
-    else
-        buffer_strcat(wb, "NONE }");
-
-    buffer_strcat(wb, ", metrics: { ");
-    if(ri->rrdmetrics) {
-        RRDMETRIC *v;
-        int i = 0;
-        dfe_start_read((DICTIONARY *)ri->rrdmetrics, v) {
-            buffer_sprintf(wb, "%s%s", i?",":"", v_name);
-            i++;
-        }
-        dfe_done(v);
-
-        if(!i)
-            buffer_strcat(wb, "EMPTY }");
-        else
-            buffer_strcat(wb, " }");
-    }
-    else
-        buffer_strcat(wb, "NONE }");
-
-    internal_error(true, "%s", buffer_tostring(wb));
-    buffer_free(wb);
-}
-#else
-#define rrdinstance_log(ir, msg) debug_dummy()
-#endif
-
-// ----------------------------------------------------------------------------
 // RRDMETRIC
 
+// free the contents of RRDMETRIC.
+// RRDMETRIC itself is managed by DICTIONARY - no need to free it here.
 static void rrdmetric_free(RRDMETRIC *rm) {
     string_freez(rm->id);
     string_freez(rm->name);
@@ -471,77 +479,24 @@ static void rrdmetric_free(RRDMETRIC *rm) {
     rm->ri = NULL;
 }
 
-static void rrdmetric_update_retention(RRDMETRIC *rm) {
-    time_t min_first_time_t = LONG_MAX, max_last_time_t = 0;
-
-    if(rm->rrddim) {
-        min_first_time_t = rrddim_first_entry_t(rm->rrddim);
-        max_last_time_t = rrddim_last_entry_t(rm->rrddim);
-    }
-#ifdef ENABLE_DBENGINE
-    else {
-        RRDHOST *rrdhost = rm->ri->rc->rrdhost;
-        for (int tier = 0; tier < storage_tiers; tier++) {
-            if(!rrdhost->storage_instance[tier]) continue;
-
-            time_t first_time_t, last_time_t;
-            if (rrdeng_metric_retention_by_uuid(rrdhost->storage_instance[tier], &rm->uuid, &first_time_t, &last_time_t) == 0) {
-                if (first_time_t < min_first_time_t)
-                    min_first_time_t = first_time_t;
-
-                if (last_time_t > max_last_time_t)
-                    max_last_time_t = last_time_t;
-            }
-        }
-    }
-#endif
-
-    if(min_first_time_t == LONG_MAX)
-        min_first_time_t = 0;
-
-    if(min_first_time_t > max_last_time_t) {
-        internal_error(true, "RRDMETRIC: retention of '%s' is flipped", string2str(rm->id));
-        time_t tmp = min_first_time_t;
-        min_first_time_t = max_last_time_t;
-        max_last_time_t = tmp;
-    }
-
-    // check if retention changed
-
-   if (min_first_time_t != rm->first_time_t) {
-        rm->first_time_t = min_first_time_t;
-        rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
-    }
-
-    if (max_last_time_t != rm->last_time_t) {
-        rm->last_time_t = max_last_time_t;
-        rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
-    }
-
-    if(unlikely(!rm->first_time_t && !rm->last_time_t))
-        rrd_flag_set_deleted(rm, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
-
-    rm->flags |= RRD_FLAG_LIVE_RETENTION;
-}
-
 // called when this rrdmetric is inserted to the rrdmetrics dictionary of a rrdinstance
-static void rrdmetric_insert_callback(const char *id __maybe_unused, void *value, void *data) {
+// the constructor of the rrdmetric object
+static void rrdmetric_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdinstance) {
     RRDMETRIC *rm = value;
 
     // link it to its parent
-    rm->ri = data;
+    rm->ri = rrdinstance;
 
     // remove flags that we need to figure out at runtime
-    rm->flags = rm->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS;
-
-    rm->created_ut = now_realtime_usec();
+    rm->flags = rm->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS; // no need for atomics
 
     // signal the react callback to do the job
     rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_NEW_OBJECT);
 }
 
 // called when this rrdmetric is deleted from the rrdmetrics dictionary of a rrdinstance
-static void rrdmetric_delete_callback(const char *id __maybe_unused, void *value, void *data __maybe_unused) {
+// the destructor of the rrdmetric object
+static void rrdmetric_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdinstance __maybe_unused) {
     RRDMETRIC *rm = value;
 
     internal_error(rm->rrddim, "RRDMETRIC: '%s' is freed but there is a RRDDIM linked to it.", string2str(rm->id));
@@ -551,21 +506,49 @@ static void rrdmetric_delete_callback(const char *id __maybe_unused, void *value
 }
 
 // called when the same rrdmetric is inserted again to the rrdmetrics dictionary of a rrdinstance
-static void rrdmetric_conflict_callback(const char *id __maybe_unused, void *oldv, void *newv, void *data __maybe_unused) {
-    RRDMETRIC *rm     = oldv;
-    RRDMETRIC *rm_new = newv;
+// while this is called, the dictionary is write locked, but there may be other users of the object
+static bool rrdmetric_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *old_value, void *new_value, void *rrdinstance __maybe_unused) {
+    RRDMETRIC *rm     = old_value;
+    RRDMETRIC *rm_new = new_value;
 
     internal_error(rm->id != rm_new->id,
                    "RRDMETRIC: '%s' cannot change id to '%s'",
                    string2str(rm->id), string2str(rm_new->id));
 
     if(uuid_compare(rm->uuid, rm_new->uuid) != 0) {
+#ifdef NETDATA_INTERNAL_CHECKS
         char uuid1[UUID_STR_LEN], uuid2[UUID_STR_LEN];
         uuid_unparse(rm->uuid, uuid1);
         uuid_unparse(rm_new->uuid, uuid2);
-        internal_error(true, "RRDMETRIC: '%s' of instance '%s' changed uuid from '%s' to '%s'", string2str(rm->id), string2str(rm->ri->id), uuid1, uuid2);
+
+        time_t old_first_time_t = 0;
+        time_t old_last_time_t = 0;
+        if(rrdmetric_update_retention(rm)) {
+            old_first_time_t = rm->first_time_t;
+            old_last_time_t = rm->last_time_t;
+        }
+
+        uuid_copy(rm->uuid, rm_new->uuid);
+
+        time_t new_first_time_t = 0;
+        time_t new_last_time_t = 0;
+        if(rrdmetric_update_retention(rm)) {
+            new_first_time_t = rm->first_time_t;
+            new_last_time_t = rm->last_time_t;
+        }
+
+        internal_error(true,
+                       "RRDMETRIC: '%s' of instance '%s' of host '%s' changed UUID from '%s' (retention %ld to %ld, %ld secs) to '%s' (retention %ld to %ld, %ld secs)"
+                       , string2str(rm->id)
+                       , string2str(rm->ri->id)
+                       , rrdhost_hostname(rm->ri->rc->rrdhost)
+                       , uuid1, old_first_time_t, old_last_time_t, old_last_time_t - old_first_time_t
+                       , uuid2, new_first_time_t, new_last_time_t, new_last_time_t - new_first_time_t
+                       );
+#else
         uuid_copy(rm->uuid, rm_new->uuid);
-        rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_UUID);
+#endif
+        rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(rm->rrddim && rm_new->rrddim && rm->rrddim != rm_new->rrddim) {
@@ -573,12 +556,14 @@ static void rrdmetric_conflict_callback(const char *id __maybe_unused, void *old
         rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_LINKING);
     }
 
+#ifdef NETDATA_INTERNAL_CHECKS
     if(rm->rrddim && uuid_compare(rm->uuid, rm->rrddim->metric_uuid) != 0) {
         char uuid1[UUID_STR_LEN], uuid2[UUID_STR_LEN];
         uuid_unparse(rm->uuid, uuid1);
         uuid_unparse(rm_new->uuid, uuid2);
-        internal_error(true, "RRDMETRIC: '%s' is linked to RRDDIM '%s' but they have different UUIDs. RRDMETRIC has '%s', RRDDIM has '%s'", string2str(rm->id), rm->rrddim->id, uuid1, uuid2);
+        internal_error(true, "RRDMETRIC: '%s' is linked to RRDDIM '%s' but they have different UUIDs. RRDMETRIC has '%s', RRDDIM has '%s'", string2str(rm->id), rrddim_id(rm->rrddim), uuid1, uuid2);
     }
+#endif
 
     if(rm->rrddim != rm_new->rrddim)
         rm->rrddim = rm_new->rrddim;
@@ -587,7 +572,7 @@ static void rrdmetric_conflict_callback(const char *id __maybe_unused, void *old
         STRING *old = rm->name;
         rm->name = string_dup(rm_new->name);
         string_freez(old);
-        rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_NAME);
+        rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(!rm->first_time_t || (rm_new->first_time_t && rm_new->first_time_t < rm->first_time_t)) {
@@ -600,98 +585,74 @@ static void rrdmetric_conflict_callback(const char *id __maybe_unused, void *old
         rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
     }
 
-    rm->flags |= (rm_new->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS);
+    rrd_flag_set(rm, rm_new->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS); // no needs for atomics on rm_new
 
     if(rrd_flag_is_collected(rm) && rrd_flag_is_archived(rm))
         rrd_flag_set_collected(rm);
 
-    if(rm->flags & RRD_FLAG_UPDATED)
-        rm->flags |= RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT;
+    if(rrd_flag_check(rm, RRD_FLAG_UPDATED))
+        rrd_flag_set(rm, RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT);
 
     rrdmetric_free(rm_new);
 
     // the react callback will continue from here
+    return rrd_flag_is_updated(rm);
 }
 
-static void rrdmetric_react_callback(const char *id __maybe_unused, void *value, void *data __maybe_unused) {
+// this is called after the insert or the conflict callbacks,
+// but the dictionary is now unlocked
+static void rrdmetric_react_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdinstance __maybe_unused) {
     RRDMETRIC *rm = value;
-
-    rrdmetric_trigger_updates(rm, false, true);
+    rrdmetric_trigger_updates(rm, __FUNCTION__ );
 }
 
-static void rrdmetrics_create(RRDINSTANCE *ri) {
+static void rrdmetrics_create_in_rrdinstance(RRDINSTANCE *ri) {
     if(unlikely(!ri)) return;
     if(likely(ri->rrdmetrics)) return;
 
-    ri->rrdmetrics = dictionary_create(DICTIONARY_FLAG_DONT_OVERWRITE_VALUE);
-    dictionary_register_insert_callback(ri->rrdmetrics, rrdmetric_insert_callback, (void *)ri);
-    dictionary_register_delete_callback(ri->rrdmetrics, rrdmetric_delete_callback, (void *)ri);
-    dictionary_register_conflict_callback(ri->rrdmetrics, rrdmetric_conflict_callback, (void *)ri);
-    dictionary_register_react_callback(ri->rrdmetrics, rrdmetric_react_callback, (void *)ri);
+    ri->rrdmetrics = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
+    dictionary_register_insert_callback(ri->rrdmetrics, rrdmetric_insert_callback, ri);
+    dictionary_register_delete_callback(ri->rrdmetrics, rrdmetric_delete_callback, ri);
+    dictionary_register_conflict_callback(ri->rrdmetrics, rrdmetric_conflict_callback, ri);
+    dictionary_register_react_callback(ri->rrdmetrics, rrdmetric_react_callback, ri);
 }
 
-static void rrdmetrics_destroy(RRDINSTANCE *ri) {
+static void rrdmetrics_destroy_from_rrdinstance(RRDINSTANCE *ri) {
     if(unlikely(!ri || !ri->rrdmetrics)) return;
     dictionary_destroy(ri->rrdmetrics);
     ri->rrdmetrics = NULL;
 }
 
-static inline bool rrdmetric_should_be_deleted(RRDMETRIC *rm) {
-    if(likely(!(rm->flags & RRD_FLAG_DELETED)))
-        return false;
-
-    if(likely(!(rm->flags & RRD_FLAG_LIVE_RETENTION)))
-        return false;
-
-    if(unlikely(rm->flags & RRD_FLAGS_PREVENTING_DELETIONS))
-        return false;
-
-    if(likely(rm->rrddim))
-        return false;
-
-    if((now_realtime_usec() - rm->created_ut) < 600 * USEC_PER_SEC)
-        return false;
-
-    rrdmetric_update_retention(rm);
-    if(rm->first_time_t || rm->last_time_t)
-        return false;
-
-    return true;
-}
-
-static void rrdmetric_trigger_updates(RRDMETRIC *rm, bool force, bool escalate) {
-    if(likely(!force && !(rm->flags & RRD_FLAG_UPDATED))) return;
-
-    if(unlikely(rrd_flag_is_collected(rm) && !rm->rrddim))
-        rrd_flag_set_archived(rm);
-
-    if(unlikely((rm->flags & RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD) && rrd_flag_is_collected(rm)))
-        rrd_flag_set_archived(rm);
-
-    rrdmetric_update_retention(rm);
+// trigger post-processing of the rrdmetric, escalating changes to the rrdinstance it belongs
+static void rrdmetric_trigger_updates(RRDMETRIC *rm, const char *function) {
+    if(unlikely(rrd_flag_is_collected(rm)) && (!rm->rrddim || rrd_flag_check(rm, RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD)))
+            rrd_flag_set_archived(rm);
 
-    if(unlikely(escalate && rm->flags & RRD_FLAG_UPDATED && !(rm->ri->flags & RRD_FLAG_DONT_PROCESS))) {
-        log_transition(rm->id, rm->ri->id, rm->ri->rc->id, rm->flags, "RRDMETRIC");
-        rrdinstance_trigger_updates(rm->ri, true, true);
+    if(rrd_flag_is_updated(rm) || !rrd_flag_check(rm, RRD_FLAG_LIVE_RETENTION)) {
+        rrd_flag_set_updated(rm->ri, RRD_FLAG_UPDATE_REASON_TRIGGERED);
+        rrdcontext_queue_for_post_processing(rm->ri->rc, function, rm->flags);
     }
 }
 
+// ----------------------------------------------------------------------------
+// RRDMETRIC HOOKS ON RRDDIM
+
 static inline void rrdmetric_from_rrddim(RRDDIM *rd) {
     if(unlikely(!rd->rrdset))
-        fatal("RRDMETRIC: rrddim '%s' does not have a rrdset.", rd->id);
+        fatal("RRDMETRIC: rrddim '%s' does not have a rrdset.", rrddim_id(rd));
 
     if(unlikely(!rd->rrdset->rrdhost))
-        fatal("RRDMETRIC: rrdset '%s' does not have a rrdhost", rd->rrdset->id);
+        fatal("RRDMETRIC: rrdset '%s' does not have a rrdhost", rrdset_id(rd->rrdset));
 
     if(unlikely(!rd->rrdset->rrdinstance))
-        fatal("RRDMETRIC: rrdset '%s' does not have a rrdinstance", rd->rrdset->id);
+        fatal("RRDMETRIC: rrdset '%s' does not have a rrdinstance", rrdset_id(rd->rrdset));
 
     RRDINSTANCE *ri = rrdinstance_acquired_value(rd->rrdset->rrdinstance);
 
     RRDMETRIC trm = {
-        .id = string_strdupz(rd->id),
-        .name = string_strdupz(rd->name),
-        .flags = RRD_FLAG_NONE,
+        .id = string_dup(rd->id),
+        .name = string_dup(rd->name),
+        .flags = RRD_FLAG_NONE, // no need for atomics
         .rrddim = rd,
     };
     uuid_copy(trm.uuid, rd->metric_uuid);
@@ -707,14 +668,18 @@ static inline void rrdmetric_from_rrddim(RRDDIM *rd) {
 #define rrddim_get_rrdmetric(rd) rrddim_get_rrdmetric_with_trace(rd, __FUNCTION__)
 static inline RRDMETRIC *rrddim_get_rrdmetric_with_trace(RRDDIM *rd, const char *function) {
     if(unlikely(!rd->rrdmetric)) {
-        error("RRDMETRIC: RRDDIM '%s' is not linked to an RRDMETRIC at %s()", rd->id, function);
+        error("RRDMETRIC: RRDDIM '%s' is not linked to an RRDMETRIC at %s()", rrddim_id(rd), function);
         return NULL;
     }
 
     RRDMETRIC *rm = rrdmetric_acquired_value(rd->rrdmetric);
+    if(unlikely(!rm)) {
+        error("RRDMETRIC: RRDDIM '%s' lost the link to its RRDMETRIC at %s()", rrddim_id(rd), function);
+        return NULL;
+    }
 
     if(unlikely(rm->rrddim != rd))
-        fatal("RRDMETRIC: '%s' is not linked to RRDDIM '%s' at %s()", string2str(rm->id), rd->id, function);
+        fatal("RRDMETRIC: '%s' is not linked to RRDDIM '%s' at %s()", string2str(rm->id), rrddim_id(rd), function);
 
     return rm;
 }
@@ -727,7 +692,7 @@ static inline void rrdmetric_rrddim_is_freed(RRDDIM *rd) {
         rrd_flag_set_archived(rm);
 
     rm->rrddim = NULL;
-    rrdmetric_trigger_updates(rm, false, true);
+    rrdmetric_trigger_updates(rm, __FUNCTION__ );
     rrdmetric_release(rd->rrdmetric);
     rd->rrdmetric = NULL;
 }
@@ -736,12 +701,12 @@ static inline void rrdmetric_updated_rrddim_flags(RRDDIM *rd) {
     RRDMETRIC *rm = rrddim_get_rrdmetric(rd);
     if(unlikely(!rm)) return;
 
-    if(unlikely(rd->flags & (RRDDIM_FLAG_ARCHIVED | RRDDIM_FLAG_OBSOLETE))) {
+    if(unlikely(rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED|RRDDIM_FLAG_OBSOLETE))) {
         if(unlikely(rrd_flag_is_collected(rm)))
             rrd_flag_set_archived(rm);
     }
 
-    rrdmetric_trigger_updates(rm, false, true);
+    rrdmetric_trigger_updates(rm, __FUNCTION__ );
 }
 
 static inline void rrdmetric_collected_rrddim(RRDDIM *rd) {
@@ -751,7 +716,10 @@ static inline void rrdmetric_collected_rrddim(RRDDIM *rd) {
     if(unlikely(!rrd_flag_is_collected(rm)))
         rrd_flag_set_collected(rm);
 
-    rrdmetric_trigger_updates(rm, false, true);
+    // we use this variable to detect BEGIN/END without SET
+    rm->ri->internal.collected_metrics_count++;
+
+    rrdmetric_trigger_updates(rm, __FUNCTION__ );
 }
 
 // ----------------------------------------------------------------------------
@@ -759,10 +727,10 @@ static inline void rrdmetric_collected_rrddim(RRDDIM *rd) {
 
 static void rrdinstance_free(RRDINSTANCE *ri) {
 
-    if(ri->flags & RRD_FLAG_OWN_LABELS)
+    if(rrd_flag_check(ri, RRD_FLAG_OWN_LABELS))
         dictionary_destroy(ri->rrdlabels);
 
-    rrdmetrics_destroy(ri);
+    rrdmetrics_destroy_from_rrdinstance(ri);
     string_freez(ri->id);
     string_freez(ri->name);
     string_freez(ri->title);
@@ -780,7 +748,7 @@ static void rrdinstance_free(RRDINSTANCE *ri) {
     ri->rrdset = NULL;
 }
 
-static void rrdinstance_insert_callback(const char *id __maybe_unused, void *value, void *data) {
+static void rrdinstance_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdcontext) {
     static STRING *ml_anomaly_rates_id = NULL;
 
     if(unlikely(!ml_anomaly_rates_id))
@@ -789,64 +757,66 @@ static void rrdinstance_insert_callback(const char *id __maybe_unused, void *val
     RRDINSTANCE *ri = value;
 
     // link it to its parent
-    ri->rc = data;
+    ri->rc = rrdcontext;
 
-    ri->flags = ri->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS;
+    ri->flags = ri->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS; // no need for atomics
 
     if(!ri->name)
         ri->name = string_dup(ri->id);
 
-    if(ri->rrdset && ri->rrdset->state) {
-        ri->rrdlabels = ri->rrdset->state->chart_labels;
-        if(ri->flags & RRD_FLAG_OWN_LABELS)
-            ri->flags &= ~RRD_FLAG_OWN_LABELS;
+    if(ri->rrdset) {
+        ri->rrdlabels = ri->rrdset->rrdlabels;
+        ri->flags &= ~RRD_FLAG_OWN_LABELS; // no need of atomics at the constructor
     }
     else {
         ri->rrdlabels = rrdlabels_create();
-        ri->flags |= RRD_FLAG_OWN_LABELS;
+        ri->flags |= RRD_FLAG_OWN_LABELS; // no need of atomics at the constructor
     }
 
     if(ri->rrdset) {
-        if(unlikely((ri->rrdset->flags & RRDSET_FLAG_HIDDEN) || (ri->rrdset->state && ri->rrdset->state->is_ar_chart)))
-            ri->flags |= RRD_FLAG_HIDDEN;
+        if(unlikely(rrdset_flag_check(ri->rrdset, RRDSET_FLAG_HIDDEN)))
+            ri->flags |= RRD_FLAG_HIDDEN; // no need of atomics at the constructor
         else
-            ri->flags &= ~RRD_FLAG_HIDDEN;
+            ri->flags &= ~RRD_FLAG_HIDDEN; // no need of atomics at the constructor
     }
 
     // we need this when loading from SQL
     if(unlikely(ri->id == ml_anomaly_rates_id))
-        ri->flags |= RRD_FLAG_HIDDEN;
+        ri->flags |= RRD_FLAG_HIDDEN; // no need of atomics at the constructor
 
-    rrdmetrics_create(ri);
-    rrdinstance_log(ri, "INSERT");
+    rrdmetrics_create_in_rrdinstance(ri);
 
     // signal the react callback to do the job
     rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_NEW_OBJECT);
 }
 
-static void rrdinstance_delete_callback(const char *id, void *value, void *data) {
-    (void)id;
-    RRDCONTEXT *rc = data; (void)rc;
+static void rrdinstance_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdcontext __maybe_unused) {
     RRDINSTANCE *ri = (RRDINSTANCE *)value;
 
-    rrdinstance_log(ri, "DELETE");
-
     internal_error(ri->rrdset, "RRDINSTANCE: '%s' is freed but there is a RRDSET linked to it.", string2str(ri->id));
 
     rrdinstance_free(ri);
 }
 
-static void rrdinstance_conflict_callback(const char *id __maybe_unused, void *oldv, void *newv, void *data __maybe_unused) {
-    RRDINSTANCE *ri     = (RRDINSTANCE *)oldv;
-    RRDINSTANCE *ri_new = (RRDINSTANCE *)newv;
+static bool rrdinstance_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *old_value, void *new_value, void *rrdcontext __maybe_unused) {
+    RRDINSTANCE *ri     = (RRDINSTANCE *)old_value;
+    RRDINSTANCE *ri_new = (RRDINSTANCE *)new_value;
 
     internal_error(ri->id != ri_new->id,
                    "RRDINSTANCE: '%s' cannot change id to '%s'",
                    string2str(ri->id), string2str(ri_new->id));
 
     if(uuid_compare(ri->uuid, ri_new->uuid) != 0) {
+#ifdef NETDATA_INTERNAL_CHECKS
+        char uuid1[UUID_STR_LEN], uuid2[UUID_STR_LEN];
+        uuid_unparse(ri->uuid, uuid1);
+        uuid_unparse(ri_new->uuid, uuid2);
+        internal_error(true, "RRDINSTANCE: '%s' of host '%s' changed UUID from '%s' to '%s'",
+                       string2str(ri->id), rrdhost_hostname(ri->rc->rrdhost), uuid1, uuid2);
+#endif
+
         uuid_copy(ri->uuid, ri_new->uuid);
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_UUID);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(ri->rrdset && ri_new->rrdset && ri->rrdset != ri_new->rrdset) {
@@ -854,270 +824,156 @@ static void rrdinstance_conflict_callback(const char *id __maybe_unused, void *o
         rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_LINKING);
     }
 
-    if(ri->rrdset && ri->rrdset->chart_uuid && uuid_compare(ri->uuid, *ri->rrdset->chart_uuid) != 0) {
+#ifdef NETDATA_INTERNAL_CHECKS
+    if(ri->rrdset && uuid_compare(ri->uuid, ri->rrdset->chart_uuid) != 0) {
         char uuid1[UUID_STR_LEN], uuid2[UUID_STR_LEN];
         uuid_unparse(ri->uuid, uuid1);
-        uuid_unparse(*ri->rrdset->chart_uuid, uuid2);
-        internal_error(true, "RRDINSTANCE: '%s' is linked to RRDSET '%s' but they have different UUIDs. RRDINSTANCE has '%s', RRDSET has '%s'", string2str(ri->id), ri->rrdset->id, uuid1, uuid2);
+        uuid_unparse(ri->rrdset->chart_uuid, uuid2);
+        internal_error(true, "RRDINSTANCE: '%s' is linked to RRDSET '%s' but they have different UUIDs. RRDINSTANCE has '%s', RRDSET has '%s'", string2str(ri->id), rrdset_id(ri->rrdset), uuid1, uuid2);
     }
+#endif
 
     if(ri->name != ri_new->name) {
         STRING *old = ri->name;
         ri->name = string_dup(ri_new->name);
         string_freez(old);
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_NAME);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(ri->title != ri_new->title) {
         STRING *old = ri->title;
         ri->title = string_dup(ri_new->title);
         string_freez(old);
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_TITLE);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(ri->units != ri_new->units) {
         STRING *old = ri->units;
         ri->units = string_dup(ri_new->units);
         string_freez(old);
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_UNITS);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(ri->family != ri_new->family) {
         STRING *old = ri->family;
         ri->family = string_dup(ri_new->family);
         string_freez(old);
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FAMILY);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(ri->chart_type != ri_new->chart_type) {
         ri->chart_type = ri_new->chart_type;
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_CHART_TYPE);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(ri->priority != ri_new->priority) {
         ri->priority = ri_new->priority;
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_PRIORITY);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(ri->update_every != ri_new->update_every) {
         ri->update_every = ri_new->update_every;
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_UPDATE_EVERY);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(ri->rrdset != ri_new->rrdset) {
         ri->rrdset = ri_new->rrdset;
 
-        if(ri->rrdset && (ri->flags & RRD_FLAG_OWN_LABELS)) {
+        if(ri->rrdset && rrd_flag_check(ri, RRD_FLAG_OWN_LABELS)) {
             DICTIONARY *old = ri->rrdlabels;
-            ri->rrdlabels = ri->rrdset->state->chart_labels;
-            ri->flags &= ~RRD_FLAG_OWN_LABELS;
+            ri->rrdlabels = ri->rrdset->rrdlabels;
+            rrd_flag_clear(ri, RRD_FLAG_OWN_LABELS);
             rrdlabels_destroy(old);
         }
-        else if(!ri->rrdset && !(ri->flags & RRD_FLAG_OWN_LABELS)) {
+        else if(!ri->rrdset && !rrd_flag_check(ri, RRD_FLAG_OWN_LABELS)) {
             ri->rrdlabels = rrdlabels_create();
-            ri->flags |= RRD_FLAG_OWN_LABELS;
+            rrd_flag_set(ri, RRD_FLAG_OWN_LABELS);
         }
     }
 
     if(ri->rrdset) {
-        if(unlikely((ri->rrdset->flags & RRDSET_FLAG_HIDDEN) || (ri->rrdset->state && ri->rrdset->state->is_ar_chart)))
-            ri->flags |= RRD_FLAG_HIDDEN;
+        if(unlikely(rrdset_flag_check(ri->rrdset, RRDSET_FLAG_HIDDEN)))
+            rrd_flag_set(ri, RRD_FLAG_HIDDEN);
         else
-            ri->flags &= ~RRD_FLAG_HIDDEN;
+            rrd_flag_clear(ri, RRD_FLAG_HIDDEN);
     }
 
-    ri->flags |= (ri_new->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS);
+    rrd_flag_set(ri, ri_new->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS); // no need for atomics on ri_new
 
     if(rrd_flag_is_collected(ri) && rrd_flag_is_archived(ri))
         rrd_flag_set_collected(ri);
 
-    if(ri->flags & RRD_FLAG_UPDATED)
-        ri->flags |= RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT;
-
-    rrdinstance_log(ri, "CONFLICT");
+    if(rrd_flag_is_updated(ri))
+        rrd_flag_set(ri, RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT);
 
     // free the new one
     rrdinstance_free(ri_new);
 
     // the react callback will continue from here
+    return rrd_flag_is_updated(ri);
 }
 
-static void rrdinstance_react_callback(const char *id __maybe_unused, void *value, void *data __maybe_unused) {
+static void rrdinstance_react_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdcontext __maybe_unused) {
     RRDINSTANCE *ri = value;
 
-    rrdinstance_trigger_updates(ri, false, true);
+    rrdinstance_trigger_updates(ri, __FUNCTION__ );
 }
 
-void rrdinstances_create(RRDCONTEXT *rc) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
+void rrdinstances_create_in_rrdcontext(RRDCONTEXT *rc) {
     if(unlikely(!rc || rc->rrdinstances)) return;
 
-    rc->rrdinstances = dictionary_create(DICTIONARY_FLAG_DONT_OVERWRITE_VALUE);
-    dictionary_register_insert_callback(rc->rrdinstances, rrdinstance_insert_callback, (void *)rc);
-    dictionary_register_delete_callback(rc->rrdinstances, rrdinstance_delete_callback, (void *)rc);
-    dictionary_register_conflict_callback(rc->rrdinstances, rrdinstance_conflict_callback, (void *)rc);
-    dictionary_register_react_callback(rc->rrdinstances, rrdinstance_react_callback, (void *)rc);
+    rc->rrdinstances = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
+    dictionary_register_insert_callback(rc->rrdinstances, rrdinstance_insert_callback, rc);
+    dictionary_register_delete_callback(rc->rrdinstances, rrdinstance_delete_callback, rc);
+    dictionary_register_conflict_callback(rc->rrdinstances, rrdinstance_conflict_callback, rc);
+    dictionary_register_react_callback(rc->rrdinstances, rrdinstance_react_callback, rc);
 }
 
-void rrdinstances_destroy(RRDCONTEXT *rc) {
+void rrdinstances_destroy_from_rrdcontext(RRDCONTEXT *rc) {
     if(unlikely(!rc || !rc->rrdinstances)) return;
 
     dictionary_destroy(rc->rrdinstances);
     rc->rrdinstances = NULL;
 }
 
-static inline bool rrdinstance_should_be_deleted(RRDINSTANCE *ri) {
-    if(likely(!(ri->flags & RRD_FLAG_DELETED)))
-        return false;
-
-    if(likely(!(ri->flags & RRD_FLAG_LIVE_RETENTION)))
-        return false;
-
-    if(unlikely(ri->flags & RRD_FLAGS_PREVENTING_DELETIONS))
-        return false;
-
-    if(likely(ri->rrdset))
-        return false;
-
-    if(unlikely(dictionary_stats_referenced_items(ri->rrdmetrics) != 0))
-        return false;
-
-    if(unlikely(dictionary_stats_entries(ri->rrdmetrics) != 0))
-        return false;
-
-    if(ri->first_time_t || ri->last_time_t)
-        return false;
-
-    return true;
-}
-
-static void rrdinstance_trigger_updates(RRDINSTANCE *ri, bool force, bool escalate) {
-    if(unlikely(ri->flags & RRD_FLAG_DONT_PROCESS)) return;
-    if(unlikely(!force && !(ri->flags & RRD_FLAG_UPDATED))) return;
+static void rrdinstance_trigger_updates(RRDINSTANCE *ri, const char *function) {
+    RRDSET *st = ri->rrdset;
 
-    if(likely(ri->rrdset)) {
-        if(unlikely(ri->rrdset->priority != ri->priority)) {
-            ri->priority = ri->rrdset->priority;
-            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_PRIORITY);
+    if(likely(st)) {
+        if(unlikely((unsigned int) st->priority != ri->priority)) {
+            ri->priority = st->priority;
+            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
         }
-        if(unlikely(ri->rrdset->update_every != ri->update_every)) {
-            ri->update_every = ri->rrdset->update_every;
-            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_UPDATE_EVERY);
+        if(unlikely(st->update_every != ri->update_every)) {
+            ri->update_every = st->update_every;
+            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
         }
     }
     else if(unlikely(rrd_flag_is_collected(ri))) {
+        // there is no rrdset, but we have it as collected!
+
         rrd_flag_set_archived(ri);
         rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_LINKING);
     }
 
-    time_t min_first_time_t = LONG_MAX, max_last_time_t = 0;
-    size_t metrics_active = 0, metrics_deleted = 0;
-    bool live_retention = true, currently_collected = false;
-    {
-        RRDMETRIC *rm;
-        dfe_start_read((DICTIONARY *)ri->rrdmetrics, rm) {
-            if(!(rm->flags & RRD_FLAG_LIVE_RETENTION))
-                live_retention = false;
-
-            if (unlikely((rrdmetric_should_be_deleted(rm)))) {
-                metrics_deleted++;
-                rrd_flag_unset_updated(rm);
-                continue;
-            }
-
-            if(rm->flags & RRD_FLAG_COLLECTED)
-                currently_collected = true;
-
-            metrics_active++;
-
-            if (rm->first_time_t && rm->first_time_t < min_first_time_t)
-                min_first_time_t = rm->first_time_t;
-
-            if (rm->last_time_t && rm->last_time_t > max_last_time_t)
-                max_last_time_t = rm->last_time_t;
-
-            rrd_flag_unset_updated(rm);
-        }
-        dfe_done(rm);
-    }
-
-    if(live_retention && !(ri->flags & RRD_FLAG_LIVE_RETENTION))
-        ri->flags |= RRD_FLAG_LIVE_RETENTION;
-    else if(!live_retention && (ri->flags & RRD_FLAG_LIVE_RETENTION))
-        ri->flags &= ~RRD_FLAG_LIVE_RETENTION;
-
-    if(unlikely(!metrics_active)) {
-        // no metrics available
-
-        if(ri->first_time_t) {
-            ri->first_time_t = 0;
-            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
-        }
-
-        if(ri->last_time_t) {
-            ri->last_time_t = 0;
-            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
-        }
-
-        rrd_flag_set_deleted(ri, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
-    }
-    else {
-        // we have active metrics...
-
-        if (unlikely(min_first_time_t == LONG_MAX))
-            min_first_time_t = 0;
-
-        if (unlikely(min_first_time_t == 0 || max_last_time_t == 0)) {
-            if(ri->first_time_t) {
-                ri->first_time_t = 0;
-                rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
-            }
-
-            if(ri->last_time_t) {
-                ri->last_time_t = 0;
-                rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
-            }
-
-            if(unlikely(live_retention))
-                rrd_flag_set_deleted(ri, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
-        }
-        else {
-            ri->flags &= ~RRD_FLAG_UPDATE_REASON_ZERO_RETENTION;
-
-            if (unlikely(ri->first_time_t != min_first_time_t)) {
-                ri->first_time_t = min_first_time_t;
-                rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
-            }
-
-            if (unlikely(ri->last_time_t != max_last_time_t)) {
-                ri->last_time_t = max_last_time_t;
-                rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
-            }
-
-            if(likely(currently_collected))
-                rrd_flag_set_collected(ri);
-            else
-                rrd_flag_set_archived(ri);
-        }
-    }
-
-    if(unlikely(escalate && ri->flags & RRD_FLAG_UPDATED && !(ri->rc->flags & RRD_FLAG_DONT_PROCESS))) {
-        log_transition(NULL, ri->id, ri->rc->id, ri->flags, "RRDINSTANCE");
-        rrdcontext_trigger_updates(ri->rc, true);
+    if(rrd_flag_is_updated(ri) || !rrd_flag_check(ri, RRD_FLAG_LIVE_RETENTION)) {
+        rrd_flag_set_updated(ri->rc, RRD_FLAG_UPDATE_REASON_TRIGGERED);
+        rrdcontext_queue_for_post_processing(ri->rc, function, ri->flags);
     }
 }
 
+// ----------------------------------------------------------------------------
+// RRDINSTANCE HOOKS ON RRDSET
+
 static inline void rrdinstance_from_rrdset(RRDSET *st) {
     RRDCONTEXT trc = {
-        .id = string_strdupz(st->context),
-        .title = string_strdupz(st->title),
-        .units = string_strdupz(st->units),
-        .family = string_strdupz(st->family),
+        .id = string_dup(st->context),
+        .title = string_dup(st->title),
+        .units = string_dup(st->units),
+        .family = string_dup(st->family),
         .priority = st->priority,
         .chart_type = st->chart_type,
-        .flags = RRD_FLAG_NONE,
+        .flags = RRD_FLAG_NONE, // no need for atomics
         .rrdhost = st->rrdhost,
     };
 
@@ -1125,18 +981,18 @@ static inline void rrdinstance_from_rrdset(RRDSET *st) {
     RRDCONTEXT *rc = rrdcontext_acquired_value(rca);
 
     RRDINSTANCE tri = {
-        .id = string_strdupz(st->id),
-        .name = string_strdupz(st->name),
-        .units = string_strdupz(st->units),
-        .family = string_strdupz(st->family),
-        .title = string_strdupz(st->title),
+        .id = string_dup(st->id),
+        .name = string_dup(st->name),
+        .units = string_dup(st->units),
+        .family = string_dup(st->family),
+        .title = string_dup(st->title),
         .chart_type = st->chart_type,
         .priority = st->priority,
         .update_every = st->update_every,
-        .flags = RRD_FLAG_DONT_PROCESS,
+        .flags = RRD_FLAG_NONE, // no need for atomics
         .rrdset = st,
     };
-    uuid_copy(tri.uuid, *st->chart_uuid);
+    uuid_copy(tri.uuid, st->chart_uuid);
 
     RRDINSTANCE_ACQUIRED *ria = (RRDINSTANCE_ACQUIRED *)dictionary_set_and_acquire_item(rc->rrdinstances, string2str(tri.id), &tri, sizeof(tri));
 
@@ -1157,18 +1013,18 @@ static inline void rrdinstance_from_rrdset(RRDSET *st) {
     }
 
     if(rca_old && ria_old) {
-        // the chart changed context
-        RRDCONTEXT *rc_old = rrdcontext_acquired_value(rca_old);
+        // Oops! The chart changed context!
+
+        // RRDCONTEXT *rc_old = rrdcontext_acquired_value(rca_old);
         RRDINSTANCE *ri_old = rrdinstance_acquired_value(ria_old);
 
         // migrate all dimensions to the new metrics
-        rrdset_rdlock(st);
         RRDDIM *rd;
         rrddim_foreach_read(rd, st) {
             if (!rd->rrdmetric) continue;
 
             RRDMETRIC *rm_old = rrdmetric_acquired_value(rd->rrdmetric);
-            rm_old->flags = RRD_FLAG_DELETED|RRD_FLAG_UPDATED|RRD_FLAG_LIVE_RETENTION|RRD_FLAG_UPDATE_REASON_UNUSED|RRD_FLAG_UPDATE_REASON_ZERO_RETENTION;
+            rrd_flags_replace(rm_old, RRD_FLAG_DELETED|RRD_FLAG_UPDATED|RRD_FLAG_LIVE_RETENTION|RRD_FLAG_UPDATE_REASON_UNUSED|RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
             rm_old->rrddim = NULL;
             rm_old->first_time_t = 0;
             rm_old->last_time_t = 0;
@@ -1178,37 +1034,32 @@ static inline void rrdinstance_from_rrdset(RRDSET *st) {
 
             rrdmetric_from_rrddim(rd);
         }
-        rrdset_unlock(st);
+        rrddim_foreach_done(rd);
 
         // mark the old instance, ready to be deleted
-        if(!(ri_old->flags & RRD_FLAG_OWN_LABELS))
+        if(!rrd_flag_check(ri_old, RRD_FLAG_OWN_LABELS))
             ri_old->rrdlabels = rrdlabels_create();
 
-        ri_old->flags = RRD_FLAG_OWN_LABELS|RRD_FLAG_DELETED|RRD_FLAG_UPDATED|RRD_FLAG_LIVE_RETENTION|RRD_FLAG_UPDATE_REASON_UNUSED|RRD_FLAG_UPDATE_REASON_ZERO_RETENTION;
+        rrd_flags_replace(ri_old, RRD_FLAG_OWN_LABELS|RRD_FLAG_DELETED|RRD_FLAG_UPDATED|RRD_FLAG_LIVE_RETENTION|RRD_FLAG_UPDATE_REASON_UNUSED|RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
         ri_old->rrdset = NULL;
         ri_old->first_time_t = 0;
         ri_old->last_time_t = 0;
 
-        ri_old->flags &= ~RRD_FLAG_DONT_PROCESS;
-        rc_old->flags &= ~RRD_FLAG_DONT_PROCESS;
-
-        rrdinstance_trigger_updates(ri_old, true, true);
-
-        ri_old->flags |= RRD_FLAG_DONT_PROCESS;
+        rrdinstance_trigger_updates(ri_old, __FUNCTION__ );
         rrdinstance_release(ria_old);
 
         /*
         // trigger updates on the old context
-        if(!dictionary_stats_entries(rc_old->rrdinstances) && !dictionary_stats_referenced_items(rc_old->rrdinstances)) {
+        if(!dictionary_entries(rc_old->rrdinstances) && !dictionary_stats_referenced_items(rc_old->rrdinstances)) {
             rrdcontext_lock(rc_old);
             rc_old->flags = ((rc_old->flags & RRD_FLAG_QUEUED)?RRD_FLAG_QUEUED:RRD_FLAG_NONE)|RRD_FLAG_DELETED|RRD_FLAG_UPDATED|RRD_FLAG_LIVE_RETENTION|RRD_FLAG_UPDATE_REASON_UNUSED|RRD_FLAG_UPDATE_REASON_ZERO_RETENTION;
             rc_old->first_time_t = 0;
             rc_old->last_time_t = 0;
             rrdcontext_unlock(rc_old);
-            rrdcontext_trigger_updates(rc_old, true);
+            rrdcontext_trigger_updates(rc_old, __FUNCTION__ );
         }
         else
-            rrdcontext_trigger_updates(rc_old, true);
+            rrdcontext_trigger_updates(rc_old, __FUNCTION__ );
         */
 
         rrdcontext_release(rca_old);
@@ -1223,14 +1074,18 @@ static inline void rrdinstance_from_rrdset(RRDSET *st) {
 #define rrdset_get_rrdinstance(st) rrdset_get_rrdinstance_with_trace(st, __FUNCTION__);
 static inline RRDINSTANCE *rrdset_get_rrdinstance_with_trace(RRDSET *st, const char *function) {
     if(unlikely(!st->rrdinstance)) {
-        error("RRDINSTANCE: RRDSET '%s' is not linked to an RRDINSTANCE at %s()", st->id, function);
+        error("RRDINSTANCE: RRDSET '%s' is not linked to an RRDINSTANCE at %s()", rrdset_id(st), function);
         return NULL;
     }
 
     RRDINSTANCE *ri = rrdinstance_acquired_value(st->rrdinstance);
+    if(unlikely(!ri)) {
+        error("RRDINSTANCE: RRDSET '%s' lost its link to an RRDINSTANCE at %s()", rrdset_id(st), function);
+        return NULL;
+    }
 
     if(unlikely(ri->rrdset != st))
-        fatal("RRDINSTANCE: '%s' is not linked to RRDSET '%s' at %s()", string2str(ri->id), st->id, function);
+        fatal("RRDINSTANCE: '%s' is not linked to RRDSET '%s' at %s()", string2str(ri->id), rrdset_id(st), function);
 
     return ri;
 }
@@ -1241,17 +1096,15 @@ static inline void rrdinstance_rrdset_is_freed(RRDSET *st) {
 
     rrd_flag_set_archived(ri);
 
-    if(!(ri->flags & RRD_FLAG_OWN_LABELS)) {
-        ri->flags |= RRD_FLAG_OWN_LABELS;
+    if(!rrd_flag_check(ri, RRD_FLAG_OWN_LABELS)) {
         ri->rrdlabels = rrdlabels_create();
-        rrdlabels_copy(ri->rrdlabels, st->state->chart_labels);
+        rrdlabels_copy(ri->rrdlabels, st->rrdlabels);
+        rrd_flag_set(ri, RRD_FLAG_OWN_LABELS);
     }
 
     ri->rrdset = NULL;
 
-    ri->flags &= ~RRD_FLAG_DONT_PROCESS;
-    rrdinstance_trigger_updates(ri, false, true);
-    ri->flags |= RRD_FLAG_DONT_PROCESS;
+    rrdinstance_trigger_updates(ri, __FUNCTION__ );
 
     rrdinstance_release(st->rrdinstance);
     st->rrdinstance = NULL;
@@ -1260,6 +1113,14 @@ static inline void rrdinstance_rrdset_is_freed(RRDSET *st) {
     st->rrdcontext = NULL;
 }
 
+static inline void rrdinstance_rrdset_has_updated_retention(RRDSET *st) {
+    RRDINSTANCE *ri = rrdset_get_rrdinstance(st);
+    if(unlikely(!ri)) return;
+
+    rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION);
+    rrdinstance_trigger_updates(ri, __FUNCTION__ );
+}
+
 static inline void rrdinstance_updated_rrdset_name(RRDSET *st) {
     // the chart may not be initialized when this is called
     if(unlikely(!st->rrdinstance)) return;
@@ -1267,28 +1128,32 @@ static inline void rrdinstance_updated_rrdset_name(RRDSET *st) {
     RRDINSTANCE *ri = rrdset_get_rrdinstance(st);
     if(unlikely(!ri)) return;
 
-    STRING *old = ri->name;
-    ri->name = string_strdupz(st->name);
-
-    if(ri->name != old)
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_NAME);
-
-    string_freez(old);
+    if(st->name != ri->name) {
+        STRING *old = ri->name;
+        ri->name = string_dup(st->name);
+        string_freez(old);
 
-    rrdinstance_trigger_updates(ri, false, true);
+        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
+        rrdinstance_trigger_updates(ri, __FUNCTION__ );
+    }
 }
 
 static inline void rrdinstance_updated_rrdset_flags_no_action(RRDINSTANCE *ri, RRDSET *st) {
-    if(unlikely(st->flags & (RRDSET_FLAG_ARCHIVED | RRDSET_FLAG_OBSOLETE)))
-        rrd_flag_set_archived(ri);
+    if(unlikely(ri->rrdset != st))
+        fatal("RRDCONTEXT: instance '%s' is not linked to chart '%s' on host '%s'",
+              string2str(ri->id), rrdset_id(st), rrdhost_hostname(st->rrdhost));
 
-    if(unlikely((st->flags & RRDSET_FLAG_HIDDEN) && !(ri->flags & RRD_FLAG_HIDDEN))) {
-        ri->flags |= RRD_FLAG_HIDDEN;
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FLAGS);
-    }
-    else if(unlikely(!(st->flags & RRDSET_FLAG_HIDDEN) && (ri->flags & RRD_FLAG_HIDDEN))) {
-        ri->flags &= ~RRD_FLAG_HIDDEN;
-        rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FLAGS);
+    bool st_is_hidden = rrdset_flag_check(st, RRDSET_FLAG_HIDDEN);
+    bool ri_is_hidden = rrd_flag_check(ri, RRD_FLAG_HIDDEN);
+
+    if(unlikely(st_is_hidden != ri_is_hidden)) {
+        if (unlikely(st_is_hidden && !ri_is_hidden))
+            rrd_flag_set_updated(ri, RRD_FLAG_HIDDEN | RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
+
+        else if (unlikely(!st_is_hidden && ri_is_hidden)) {
+            rrd_flag_clear(ri, RRD_FLAG_HIDDEN);
+            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
+        }
     }
 }
 
@@ -1296,11 +1161,12 @@ static inline void rrdinstance_updated_rrdset_flags(RRDSET *st) {
     RRDINSTANCE *ri = rrdset_get_rrdinstance(st);
     if(unlikely(!ri)) return;
 
+    if(unlikely(rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED|RRDSET_FLAG_OBSOLETE)))
+        rrd_flag_set_archived(ri);
+
     rrdinstance_updated_rrdset_flags_no_action(ri, st);
 
-    ri->flags &= ~RRD_FLAG_DONT_PROCESS;
-    rrdinstance_trigger_updates(ri, false, true);
-    ri->flags |= RRD_FLAG_DONT_PROCESS;
+    rrdinstance_trigger_updates(ri, __FUNCTION__ );
 }
 
 static inline void rrdinstance_collected_rrdset(RRDSET *st) {
@@ -1309,13 +1175,13 @@ static inline void rrdinstance_collected_rrdset(RRDSET *st) {
 
     rrdinstance_updated_rrdset_flags_no_action(ri, st);
 
-    if(unlikely(!rrd_flag_is_collected(ri)))
+    if(unlikely(ri->internal.collected_metrics_count && !rrd_flag_is_collected(ri)))
         rrd_flag_set_collected(ri);
 
-    if(unlikely(ri->flags & RRD_FLAG_DONT_PROCESS))
-        ri->flags &= ~RRD_FLAG_DONT_PROCESS;
+    // we use this variable to detect BEGIN/END without SET
+    ri->internal.collected_metrics_count = 0;
 
-    rrdinstance_trigger_updates(ri, false, true);
+    rrdinstance_trigger_updates(ri, __FUNCTION__ );
 }
 
 // ----------------------------------------------------------------------------
@@ -1328,131 +1194,12 @@ static void rrdcontext_freez(RRDCONTEXT *rc) {
     string_freez(rc->family);
 }
 
-static uint64_t rrdcontext_get_next_version(RRDCONTEXT *rc) {
-    time_t now = now_realtime_sec();
-    uint64_t version = MAX(rc->version, rc->hub.version);
-    version = MAX((uint64_t)now, version);
-    version++;
-    return version;
-}
-
-static void rrdcontext_message_send_unsafe(RRDCONTEXT *rc, bool snapshot __maybe_unused, void *bundle __maybe_unused) {
-
-    // save it, so that we know the last version we sent to hub
-    rc->version = rc->hub.version = rrdcontext_get_next_version(rc);
-    rc->hub.id = string2str(rc->id);
-    rc->hub.title = string2str(rc->title);
-    rc->hub.units = string2str(rc->units);
-    rc->hub.family = string2str(rc->family);
-    rc->hub.chart_type = rrdset_type_name(rc->chart_type);
-    rc->hub.priority = rc->priority;
-    rc->hub.first_time_t = rc->first_time_t;
-    rc->hub.last_time_t = rrd_flag_is_collected(rc) ? 0 : rc->last_time_t;
-    rc->hub.deleted = (rc->flags & RRD_FLAG_DELETED) ? true : false;
-
-#ifdef ENABLE_ACLK
-    struct context_updated message = {
-        .id = rc->hub.id,
-        .version = rc->hub.version,
-        .title = rc->hub.title,
-        .units = rc->hub.units,
-        .family = rc->hub.family,
-        .chart_type = rc->hub.chart_type,
-        .priority = rc->hub.priority,
-        .first_entry = rc->hub.first_time_t,
-        .last_entry = rc->hub.last_time_t,
-        .deleted = rc->hub.deleted,
-    };
-
-    if(likely(!(rc->flags & RRD_FLAG_HIDDEN))) {
-        if (snapshot) {
-            if (!rc->hub.deleted)
-                contexts_snapshot_add_ctx_update(bundle, &message);
-        }
-        else
-            contexts_updated_add_ctx_update(bundle, &message);
-    }
-#endif
-
-    // store it to SQL
-
-    if(rc->flags & RRD_FLAG_DELETED) {
-        rrdcontext_delete_from_sql_unsafe(rc);
-    }
-    else {
-        if (ctx_store_context(&rc->rrdhost->host_uuid, &rc->hub) != 0)
-            error("RRDCONTEXT: failed to save context '%s' version %"PRIu64" to SQL.", rc->hub.id, rc->hub.version);
-    }
-}
-
-static bool check_if_cloud_version_changed_unsafe(RRDCONTEXT *rc, bool sending __maybe_unused) {
-    bool id_changed = false,
-         title_changed = false,
-         units_changed = false,
-         family_changed = false,
-         chart_type_changed = false,
-         priority_changed = false,
-         first_time_changed = false,
-         last_time_changed = false,
-         deleted_changed = false;
-
-    if(unlikely(string2str(rc->id) != rc->hub.id))
-        id_changed = true;
-
-    if(unlikely(string2str(rc->title) != rc->hub.title))
-        title_changed = true;
-
-    if(unlikely(string2str(rc->units) != rc->hub.units))
-        units_changed = true;
-
-    if(unlikely(string2str(rc->family) != rc->hub.family))
-        family_changed = true;
-
-    if(unlikely(rrdset_type_name(rc->chart_type) != rc->hub.chart_type))
-        chart_type_changed = true;
-
-    if(unlikely(rc->priority != rc->hub.priority))
-        priority_changed = true;
-
-    if(unlikely((uint64_t)rc->first_time_t != rc->hub.first_time_t))
-        first_time_changed = true;
-
-    if(unlikely((uint64_t)(rrd_flag_is_collected(rc) ? 0 : rc->last_time_t) != rc->hub.last_time_t))
-        last_time_changed = true;
-
-    if(unlikely(((rc->flags & RRD_FLAG_DELETED) ? true : false) != rc->hub.deleted))
-        deleted_changed = true;
-
-    if(unlikely(id_changed || title_changed || units_changed || family_changed || chart_type_changed || priority_changed || first_time_changed || last_time_changed || deleted_changed)) {
-
-        internal_error(true, "RRDCONTEXT: %s NEW VERSION '%s'%s, version %"PRIu64", title '%s'%s, units '%s'%s, family '%s'%s, chart type '%s'%s, priority %u%s, first_time_t %ld%s, last_time_t %ld%s, deleted '%s'%s, (queued for %llu ms, expected %llu ms)",
-                       sending?"SENDING":"QUEUE",
-                       string2str(rc->id), id_changed ? " (CHANGED)" : "",
-                       rc->version,
-                       string2str(rc->title), title_changed ? " (CHANGED)" : "",
-                       string2str(rc->units), units_changed ? " (CHANGED)" : "",
-                       string2str(rc->family), family_changed ? " (CHANGED)" : "",
-                       rrdset_type_name(rc->chart_type), chart_type_changed ? " (CHANGED)" : "",
-                       rc->priority, priority_changed ? " (CHANGED)" : "",
-                       rc->first_time_t, first_time_changed ? " (CHANGED)" : "",
-                       rrd_flag_is_collected(rc) ? 0 : rc->last_time_t, last_time_changed ? " (CHANGED)" : "",
-                       (rc->flags & RRD_FLAG_DELETED) ? "true" : "false", deleted_changed ? " (CHANGED)" : "",
-                       sending ? (now_realtime_usec() - rc->queue.queued_ut) / USEC_PER_MS : 0,
-                       sending ? (rc->queue.scheduled_dispatch_ut - rc->queue.queued_ut) / USEC_PER_SEC : 0
-                       );
-        return true;
-    }
-
-    return false;
-}
-
-static void rrdcontext_insert_callback(const char *id, void *value, void *data) {
-    (void)id;
-    RRDHOST *host = (RRDHOST *)data;
+static void rrdcontext_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdhost) {
+    RRDHOST *host = (RRDHOST *)rrdhost;
     RRDCONTEXT *rc = (RRDCONTEXT *)value;
 
     rc->rrdhost = host;
-    rc->flags = rc->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS;
+    rc->flags = rc->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS; // no need for atomics at constructor
 
     if(rc->hub.version) {
         // we are loading data from the SQL database
@@ -1485,11 +1232,11 @@ static void rrdcontext_insert_callback(const char *id, void *value, void *data)
 
         rc->version      = rc->hub.version;
         rc->priority     = rc->hub.priority;
-        rc->first_time_t = rc->hub.first_time_t;
-        rc->last_time_t  = rc->hub.last_time_t;
+        rc->first_time_t = (time_t)rc->hub.first_time_t;
+        rc->last_time_t  = (time_t)rc->hub.last_time_t;
 
         if(rc->hub.deleted || !rc->hub.first_time_t)
-            rrd_flag_set_deleted(rc, 0);
+            rrd_flag_set_deleted(rc, RRD_FLAG_NONE);
         else {
             if (rc->last_time_t == 0)
                 rrd_flag_set_collected(rc);
@@ -1497,80 +1244,85 @@ static void rrdcontext_insert_callback(const char *id, void *value, void *data)
                 rrd_flag_set_archived(rc);
         }
 
-        rc->flags |= RRD_FLAG_UPDATE_REASON_LOAD_SQL;
+        rc->flags |= RRD_FLAG_UPDATE_REASON_LOAD_SQL; // no need for atomics at constructor
     }
     else {
         // we are adding this context now for the first time
         rc->version = now_realtime_sec();
     }
 
-    rrdinstances_create(rc);
+    rrdinstances_create_in_rrdcontext(rc);
     netdata_mutex_init(&rc->mutex);
 
     // signal the react callback to do the job
     rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_NEW_OBJECT);
 }
 
-static void rrdcontext_delete_callback(const char *id, void *value, void *data) {
-    (void)id;
-    RRDHOST *host = (RRDHOST *)data;
-    (void)host;
+static void rrdcontext_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdhost __maybe_unused) {
 
     RRDCONTEXT *rc = (RRDCONTEXT *)value;
 
-    rrdinstances_destroy(rc);
+    rrdinstances_destroy_from_rrdcontext(rc);
     netdata_mutex_destroy(&rc->mutex);
     rrdcontext_freez(rc);
 }
 
-static void rrdcontext_conflict_callback(const char *id, void *oldv, void *newv, void *data) {
-    (void)id;
-    RRDHOST *host = (RRDHOST *)data;
-    (void)host;
+static bool rrdcontext_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *old_value, void *new_value, void *rrdhost __maybe_unused) {
+    RRDCONTEXT *rc = (RRDCONTEXT *)old_value;
+    RRDCONTEXT *rc_new = (RRDCONTEXT *)new_value;
 
-    RRDCONTEXT *rc = (RRDCONTEXT *)oldv;
-    RRDCONTEXT *rc_new = (RRDCONTEXT *)newv;
+    //current rc is not archived, new_rc is archived, don't merge
+    if (!rrd_flag_is_archived(rc) && rrd_flag_is_archived(rc_new)) {
+        rrdcontext_freez(rc_new);
+        return false;
+    }
 
     rrdcontext_lock(rc);
 
     if(rc->title != rc_new->title) {
         STRING *old_title = rc->title;
-        rc->title = string_2way_merge(rc->title, rc_new->title);
+        if (rrd_flag_is_archived(rc) && !rrd_flag_is_archived(rc_new))
+            rc->title = string_dup(rc_new->title);
+        else
+            rc->title = string_2way_merge(rc->title, rc_new->title);
         string_freez(old_title);
-        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_TITLE);
+        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(rc->units != rc_new->units) {
         STRING *old_units = rc->units;
         rc->units = string_dup(rc_new->units);
         string_freez(old_units);
-        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_UNITS);
+        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(rc->family != rc_new->family) {
         STRING *old_family = rc->family;
-        rc->family = string_2way_merge(rc->family, rc_new->family);
+        if (rrd_flag_is_archived(rc) && !rrd_flag_is_archived(rc_new))
+            rc->family = string_dup(rc_new->family);
+        else
+            rc->family = string_2way_merge(rc->family, rc_new->family);
         string_freez(old_family);
-        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_FAMILY);
+        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(rc->chart_type != rc_new->chart_type) {
         rc->chart_type = rc_new->chart_type;
-        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_CHART_TYPE);
+        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
     if(rc->priority != rc_new->priority) {
         rc->priority = rc_new->priority;
-        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_PRIORITY);
+        rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
     }
 
-    rc->flags |= (rc_new->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS);
+    rrd_flag_set(rc, rc_new->flags & RRD_FLAGS_ALLOWED_EXTERNALLY_ON_NEW_OBJECTS); // no need for atomics on rc_new
 
     if(rrd_flag_is_collected(rc) && rrd_flag_is_archived(rc))
         rrd_flag_set_collected(rc);
 
-    if(rc->flags & RRD_FLAG_UPDATED)
-        rc->flags |= RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT;
+    if(rrd_flag_is_updated(rc))
+        rrd_flag_set(rc, RRD_FLAG_UPDATE_REASON_UPDATED_OBJECT);
 
     rrdcontext_unlock(rc);
 
@@ -1578,310 +1330,284 @@ static void rrdcontext_conflict_callback(const char *id, void *oldv, void *newv,
     rrdcontext_freez(rc_new);
 
     // the react callback will continue from here
+    return rrd_flag_is_updated(rc);
 }
 
-static void rrdcontext_react_callback(const char *id __maybe_unused, void *value, void *data __maybe_unused) {
+static void rrdcontext_react_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *rrdhost __maybe_unused) {
     RRDCONTEXT *rc = (RRDCONTEXT *)value;
-
-    rrdcontext_trigger_updates(rc, false);
+    rrdcontext_trigger_updates(rc, __FUNCTION__ );
 }
 
-void rrdhost_create_rrdcontexts(RRDHOST *host) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
-    if(unlikely(!host)) return;
-    if(likely(host->rrdctx)) return;
-
-    host->rrdctx = (RRDCONTEXTS *)dictionary_create(DICTIONARY_FLAG_DONT_OVERWRITE_VALUE);
-    dictionary_register_insert_callback((DICTIONARY *)host->rrdctx, rrdcontext_insert_callback, (void *)host);
-    dictionary_register_delete_callback((DICTIONARY *)host->rrdctx, rrdcontext_delete_callback, (void *)host);
-    dictionary_register_conflict_callback((DICTIONARY *)host->rrdctx, rrdcontext_conflict_callback, (void *)host);
-    dictionary_register_react_callback((DICTIONARY *)host->rrdctx, rrdcontext_react_callback, (void *)host);
-
-    host->rrdctx_queue = (RRDCONTEXTS *)dictionary_create(DICTIONARY_FLAG_DONT_OVERWRITE_VALUE | DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE);
+static void rrdcontext_trigger_updates(RRDCONTEXT *rc, const char *function) {
+    if(rrd_flag_is_updated(rc) || !rrd_flag_check(rc, RRD_FLAG_LIVE_RETENTION))
+        rrdcontext_queue_for_post_processing(rc, function, rc->flags);
 }
 
-void rrdhost_destroy_rrdcontexts(RRDHOST *host) {
-    if(unlikely(!host)) return;
-    if(unlikely(!host->rrdctx)) return;
-
-    if(host->rrdctx_queue) {
-        dictionary_destroy((DICTIONARY *)host->rrdctx_queue);
-        host->rrdctx_queue = NULL;
-    }
-
-    dictionary_destroy((DICTIONARY *)host->rrdctx);
-    host->rrdctx = NULL;
+static void rrdcontext_hub_queue_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *context, void *nothing __maybe_unused) {
+    RRDCONTEXT *rc = context;
+    rrd_flag_set(rc, RRD_FLAG_QUEUED_FOR_HUB);
+    rc->queue.queued_ut = now_realtime_usec();
+    rc->queue.queued_flags = rrd_flags_get(rc);
 }
 
-static inline bool rrdcontext_should_be_deleted(RRDCONTEXT *rc) {
-    if(likely(!(rc->flags & RRD_FLAG_DELETED)))
-        return false;
-
-    if(likely(!(rc->flags & RRD_FLAG_LIVE_RETENTION)))
-        return false;
-
-    if(unlikely(rc->flags & RRD_FLAGS_PREVENTING_DELETIONS))
-        return false;
-
-    if(unlikely(dictionary_stats_referenced_items(rc->rrdinstances) != 0))
-        return false;
-
-    if(unlikely(dictionary_stats_entries(rc->rrdinstances) != 0))
-        return false;
+static void rrdcontext_hub_queue_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *context, void *nothing __maybe_unused) {
+    RRDCONTEXT *rc = context;
+    rrd_flag_clear(rc, RRD_FLAG_QUEUED_FOR_HUB);
+}
 
-    if(unlikely(rc->first_time_t || rc->last_time_t))
-        return false;
+static bool rrdcontext_hub_queue_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *context, void *new_context __maybe_unused, void *nothing __maybe_unused) {
+    // context and new_context are the same
+    // we just need to update the timings
+    RRDCONTEXT *rc = context;
+    rrd_flag_set(rc, RRD_FLAG_QUEUED_FOR_HUB);
+    rc->queue.queued_ut = now_realtime_usec();
+    rc->queue.queued_flags |= rrd_flags_get(rc);
 
     return true;
 }
 
-static void rrdcontext_trigger_updates(RRDCONTEXT *rc, bool force) {
-    if(unlikely(rc->flags & RRD_FLAG_DONT_PROCESS)) return;
-    if(unlikely(!force && !(rc->flags & RRD_FLAG_UPDATED))) return;
-
-    rrdcontext_lock(rc);
-
-    size_t min_priority = LONG_MAX;
-    time_t min_first_time_t = LONG_MAX, max_last_time_t = 0;
-    size_t instances_active = 0, instances_deleted = 0;
-    bool live_retention = true, currently_collected = false, hidden = true;
-    {
-        RRDINSTANCE *ri;
-        dfe_start_read(rc->rrdinstances, ri) {
-            if(likely(!(ri->flags & RRD_FLAG_HIDDEN)))
-                hidden = false;
-
-            if(!(ri->flags & RRD_FLAG_LIVE_RETENTION))
-                live_retention = false;
-
-            if (unlikely(rrdinstance_should_be_deleted(ri))) {
-                instances_deleted++;
-                rrd_flag_unset_updated(ri);
-                continue;
-            }
-
-            if(ri->flags & RRD_FLAG_COLLECTED)
-                currently_collected = true;
-
-            internal_error(rc->units != ri->units,
-                           "RRDCONTEXT: '%s' rrdinstance '%s' has different units, context '%s', instance '%s'",
-                           string2str(rc->id), string2str(ri->id),
-                           string2str(rc->units), string2str(ri->units));
-
-            instances_active++;
-
-            if (ri->priority >= RRDCONTEXT_MINIMUM_ALLOWED_PRIORITY && ri->priority < min_priority)
-                min_priority = ri->priority;
+static void rrdcontext_post_processing_queue_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *context, void *nothing __maybe_unused) {
+    RRDCONTEXT *rc = context;
+    rrd_flag_set(rc, RRD_FLAG_QUEUED_FOR_PP);
+    rc->pp.queued_flags = rc->flags;
+    rc->pp.queued_ut = now_realtime_usec();
+}
 
-            if (ri->first_time_t && ri->first_time_t < min_first_time_t)
-                min_first_time_t = ri->first_time_t;
+static void rrdcontext_post_processing_queue_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *context, void *nothing __maybe_unused) {
+    RRDCONTEXT *rc = context;
+    rrd_flag_clear(rc, RRD_FLAG_QUEUED_FOR_PP);
+    rc->pp.dequeued_ut = now_realtime_usec();
+}
 
-            if (ri->last_time_t && ri->last_time_t > max_last_time_t)
-                max_last_time_t = ri->last_time_t;
+static bool rrdcontext_post_processing_queue_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *context, void *new_context __maybe_unused, void *nothing __maybe_unused) {
+    RRDCONTEXT *rc = context;
+    bool changed = false;
 
-            rrd_flag_unset_updated(ri);
-        }
-        dfe_done(ri);
+    if(!(rc->flags & RRD_FLAG_QUEUED_FOR_PP)) {
+        rrd_flag_set(rc, RRD_FLAG_QUEUED_FOR_PP);
+        changed = true;
     }
 
-    if(hidden && !(rc->flags & RRD_FLAG_HIDDEN))
-        rc->flags |= RRD_FLAG_HIDDEN;
-    else if(!hidden && (rc->flags & RRD_FLAG_HIDDEN))
-        rc->flags &= ~RRD_FLAG_HIDDEN;
-
-    if(live_retention && !(rc->flags & RRD_FLAG_LIVE_RETENTION))
-        rc->flags |= RRD_FLAG_LIVE_RETENTION;
-    else if(!live_retention && (rc->flags & RRD_FLAG_LIVE_RETENTION))
-        rc->flags &= ~RRD_FLAG_LIVE_RETENTION;
-
-    if(unlikely(!instances_active)) {
-        // we had some instances, but they are gone now...
-
-        if(rc->first_time_t) {
-            rc->first_time_t = 0;
-            rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
-        }
-
-        if(rc->last_time_t) {
-            rc->last_time_t = 0;
-            rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
-        }
-
-        rrd_flag_set_deleted(rc, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
+    if(rc->pp.queued_flags != rc->flags) {
+        rc->pp.queued_flags |= rc->flags;
+        changed = true;
     }
-    else {
-        // we have some active instances...
 
-        if (unlikely(min_first_time_t == LONG_MAX))
-            min_first_time_t = 0;
+    return changed;
+}
 
-        if (unlikely(min_first_time_t == 0 && max_last_time_t == 0)) {
-            if(rc->first_time_t) {
-                rc->first_time_t = 0;
-                rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
-            }
+void rrdhost_create_rrdcontexts(RRDHOST *host) {
+    if(unlikely(!host)) return;
+    if(likely(host->rrdctx)) return;
 
-            if(rc->last_time_t) {
-                rc->last_time_t = 0;
-                rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
-            }
+    host->rrdctx = (RRDCONTEXTS *)dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
+    dictionary_register_insert_callback((DICTIONARY *)host->rrdctx, rrdcontext_insert_callback, host);
+    dictionary_register_delete_callback((DICTIONARY *)host->rrdctx, rrdcontext_delete_callback, host);
+    dictionary_register_conflict_callback((DICTIONARY *)host->rrdctx, rrdcontext_conflict_callback, host);
+    dictionary_register_react_callback((DICTIONARY *)host->rrdctx, rrdcontext_react_callback, host);
 
-            rrd_flag_set_deleted(rc, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
-        }
-        else {
-            rc->flags &= ~RRD_FLAG_UPDATE_REASON_ZERO_RETENTION;
+    host->rrdctx_hub_queue = (RRDCONTEXTS *)dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE | DICT_OPTION_VALUE_LINK_DONT_CLONE);
+    dictionary_register_insert_callback((DICTIONARY *)host->rrdctx_hub_queue, rrdcontext_hub_queue_insert_callback, NULL);
+    dictionary_register_delete_callback((DICTIONARY *)host->rrdctx_hub_queue, rrdcontext_hub_queue_delete_callback, NULL);
+    dictionary_register_conflict_callback((DICTIONARY *)host->rrdctx_hub_queue, rrdcontext_hub_queue_conflict_callback, NULL);
 
-            if (unlikely(rc->first_time_t != min_first_time_t)) {
-                rc->first_time_t = min_first_time_t;
-                rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
-            }
+    host->rrdctx_post_processing_queue = (RRDCONTEXTS *)dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE | DICT_OPTION_VALUE_LINK_DONT_CLONE);
+    dictionary_register_insert_callback((DICTIONARY *)host->rrdctx_post_processing_queue, rrdcontext_post_processing_queue_insert_callback, NULL);
+    dictionary_register_delete_callback((DICTIONARY *)host->rrdctx_post_processing_queue, rrdcontext_post_processing_queue_delete_callback, NULL);
+    dictionary_register_conflict_callback((DICTIONARY *)host->rrdctx_post_processing_queue, rrdcontext_post_processing_queue_conflict_callback, NULL);
+}
 
-            if (rc->last_time_t != max_last_time_t) {
-                rc->last_time_t = max_last_time_t;
-                rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
-            }
+void rrdhost_destroy_rrdcontexts(RRDHOST *host) {
+    if(unlikely(!host)) return;
+    if(unlikely(!host->rrdctx)) return;
 
-            if(likely(currently_collected))
-                rrd_flag_set_collected(rc);
-            else
-                rrd_flag_set_archived(rc);
-        }
+    DICTIONARY *old;
 
-        if (min_priority != LONG_MAX && rc->priority != min_priority) {
-            rc->priority = min_priority;
-            rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_PRIORITY);
+    if(host->rrdctx_hub_queue) {
+        old = (DICTIONARY *)host->rrdctx_hub_queue;
+        host->rrdctx_hub_queue = NULL;
+
+        RRDCONTEXT *rc;
+        dfe_start_write(old, rc) {
+            dictionary_del(old, string2str(rc->id));
         }
+        dfe_done(rc);
+        dictionary_destroy(old);
     }
 
-    if(unlikely(rc->flags & RRD_FLAG_UPDATED)) {
-        log_transition(NULL, NULL, rc->id, rc->flags, "RRDCONTEXT");
-
-        if(check_if_cloud_version_changed_unsafe(rc, false)) {
-            rc->version = rrdcontext_get_next_version(rc);
-
-            if(rc->flags & RRD_FLAG_QUEUED) {
-                rc->queue.queued_ut = now_realtime_usec();
-                rc->queue.queued_flags |= rc->flags;
-            }
-            else {
-                rc->queue.queued_ut = now_realtime_usec();
-                rc->queue.queued_flags = rc->flags;
+    if(host->rrdctx_post_processing_queue) {
+        old = (DICTIONARY *)host->rrdctx_post_processing_queue;
+        host->rrdctx_post_processing_queue = NULL;
 
-                rc->flags |= RRD_FLAG_QUEUED;
-                dictionary_set((DICTIONARY *)rc->rrdhost->rrdctx_queue, string2str(rc->id), rc, sizeof(*rc));
-            }
+        RRDCONTEXT *rc;
+        dfe_start_write(old, rc) {
+            dictionary_del(old, string2str(rc->id));
         }
-
-        rrd_flag_unset_updated(rc);
+        dfe_done(rc);
+        dictionary_destroy(old);
     }
 
-    rrdcontext_unlock(rc);
+    old = (DICTIONARY *)host->rrdctx;
+    host->rrdctx = NULL;
+    dictionary_destroy(old);
 }
 
 // ----------------------------------------------------------------------------
 // public API
 
 void rrdcontext_updated_rrddim(RRDDIM *rd) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdmetric_from_rrddim(rd);
 }
 
 void rrdcontext_removed_rrddim(RRDDIM *rd) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdmetric_rrddim_is_freed(rd);
 }
 
 void rrdcontext_updated_rrddim_algorithm(RRDDIM *rd) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdmetric_updated_rrddim_flags(rd);
 }
 
 void rrdcontext_updated_rrddim_multiplier(RRDDIM *rd) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdmetric_updated_rrddim_flags(rd);
 }
 
 void rrdcontext_updated_rrddim_divisor(RRDDIM *rd) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdmetric_updated_rrddim_flags(rd);
 }
 
 void rrdcontext_updated_rrddim_flags(RRDDIM *rd) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdmetric_updated_rrddim_flags(rd);
 }
 
 void rrdcontext_collected_rrddim(RRDDIM *rd) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdmetric_collected_rrddim(rd);
 }
 
 void rrdcontext_updated_rrdset(RRDSET *st) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdinstance_from_rrdset(st);
 }
 
 void rrdcontext_removed_rrdset(RRDSET *st) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdinstance_rrdset_is_freed(st);
 }
 
-void rrdcontext_updated_rrdset_name(RRDSET *st) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
+void rrdcontext_updated_retention_rrdset(RRDSET *st) {
+    rrdinstance_rrdset_has_updated_retention(st);
+}
 
+void rrdcontext_updated_rrdset_name(RRDSET *st) {
     rrdinstance_updated_rrdset_name(st);
 }
 
 void rrdcontext_updated_rrdset_flags(RRDSET *st) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdinstance_updated_rrdset_flags(st);
 }
 
 void rrdcontext_collected_rrdset(RRDSET *st) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     rrdinstance_collected_rrdset(st);
 }
 
 void rrdcontext_host_child_connected(RRDHOST *host) {
     (void)host;
 
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     // no need to do anything here
     ;
 }
 
+int rrdcontext_find_dimension_uuid(RRDSET *st, const char *id, uuid_t *store_uuid) {
+    if(!st->rrdhost) return 1;
+    if(!st->context) return 2;
+
+    RRDCONTEXT_ACQUIRED *rca = (RRDCONTEXT_ACQUIRED *)dictionary_get_and_acquire_item((DICTIONARY *)st->rrdhost->rrdctx, string2str(st->context));
+    if(!rca) return 3;
+
+    RRDCONTEXT *rc = rrdcontext_acquired_value(rca);
+
+    RRDINSTANCE_ACQUIRED *ria = (RRDINSTANCE_ACQUIRED *)dictionary_get_and_acquire_item(rc->rrdinstances, string2str(st->id));
+    if(!ria) {
+        rrdcontext_release(rca);
+        return 4;
+    }
+
+    RRDINSTANCE *ri = rrdinstance_acquired_value(ria);
+
+    RRDMETRIC_ACQUIRED *rma = (RRDMETRIC_ACQUIRED *)dictionary_get_and_acquire_item(ri->rrdmetrics, id);
+    if(!rma) {
+        rrdinstance_release(ria);
+        rrdcontext_release(rca);
+        return 5;
+    }
+
+    RRDMETRIC *rm = rrdmetric_acquired_value(rma);
+
+    uuid_copy(*store_uuid, rm->uuid);
+
+    rrdmetric_release(rma);
+    rrdinstance_release(ria);
+    rrdcontext_release(rca);
+    return 0;
+}
+
+int rrdcontext_find_chart_uuid(RRDSET *st, uuid_t *store_uuid) {
+    if(!st->rrdhost) return 1;
+    if(!st->context) return 2;
+
+    RRDCONTEXT_ACQUIRED *rca = (RRDCONTEXT_ACQUIRED *)dictionary_get_and_acquire_item((DICTIONARY *)st->rrdhost->rrdctx, string2str(st->context));
+    if(!rca) return 3;
+
+    RRDCONTEXT *rc = rrdcontext_acquired_value(rca);
+
+    RRDINSTANCE_ACQUIRED *ria = (RRDINSTANCE_ACQUIRED *)dictionary_get_and_acquire_item(rc->rrdinstances, string2str(st->id));
+    if(!ria) {
+        rrdcontext_release(rca);
+        return 4;
+    }
+
+    RRDINSTANCE *ri = rrdinstance_acquired_value(ria);
+    uuid_copy(*store_uuid, ri->uuid);
+
+    rrdinstance_release(ria);
+    rrdcontext_release(rca);
+    return 0;
+}
+
 void rrdcontext_host_child_disconnected(RRDHOST *host) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
+    rrdcontext_recalculate_host_retention(host, RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD, false);
+}
+
+static usec_t rrdcontext_next_db_rotation_ut = 0;
+void rrdcontext_db_rotation(void) {
+    // called when the db rotates its database
+    rrdcontext_next_db_rotation_ut = now_realtime_usec() + FULL_RETENTION_SCAN_DELAY_AFTER_DB_ROTATION_SECS * USEC_PER_SEC;
+}
+
+int rrdcontext_foreach_instance_with_rrdset_in_context(RRDHOST *host, const char *context, int (*callback)(RRDSET *st, void *data), void *data) {
+    if(unlikely(!host || !context || !*context || !callback))
+        return -1;
+
+    RRDCONTEXT_ACQUIRED *rca = (RRDCONTEXT_ACQUIRED *)dictionary_get_and_acquire_item((DICTIONARY *)host->rrdctx, context);
+    if(unlikely(!rca)) return -1;
+
+    RRDCONTEXT *rc = rrdcontext_acquired_value(rca);
+    if(unlikely(!rc)) return -1;
 
-    rrdcontext_recalculate_host_retention(host, RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD, -1);
+    int ret = 0;
+    RRDINSTANCE *ri;
+    dfe_start_read(rc->rrdinstances, ri) {
+        if(ri->rrdset) {
+            int r = callback(ri->rrdset, data);
+            if(r >= 0) ret += r;
+            else {
+                ret = r;
+                break;
+            }
+        }
+    }
+    dfe_done(ri);
+
+    rrdcontext_release(rca);
+
+    return ret;
 }
 
 // ----------------------------------------------------------------------------
@@ -1933,7 +1659,7 @@ void rrdcontext_hub_checkpoint_command(void *ptr) {
 
     if(rrdhost_flag_check(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS)) {
         info("RRDCONTEXT: received checkpoint command for claim id '%s', node id '%s', while node '%s' has an active context streaming.",
-              cmd->claim_id, cmd->node_id, host->hostname);
+              cmd->claim_id, cmd->node_id, rrdhost_hostname(host));
 
         // disable it temporarily, so that our worker will not attempt to send messages in parallel
         rrdhost_flag_clear(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS);
@@ -1943,7 +1669,7 @@ void rrdcontext_hub_checkpoint_command(void *ptr) {
 
     if(cmd->version_hash != our_version_hash) {
         error("RRDCONTEXT: received version hash %"PRIu64" for host '%s', does not match our version hash %"PRIu64". Sending snapshot of all contexts.",
-              cmd->version_hash, host->hostname, our_version_hash);
+              cmd->version_hash, rrdhost_hostname(host), our_version_hash);
 
 #ifdef ENABLE_ACLK
         // prepare the snapshot
@@ -1952,7 +1678,7 @@ void rrdcontext_hub_checkpoint_command(void *ptr) {
         contexts_snapshot_t bundle = contexts_snapshot_new(cmd->claim_id, uuid, our_version_hash);
 
         // do a deep scan on every metric of the host to make sure all our data are updated
-        rrdcontext_recalculate_host_retention(host, RRD_FLAG_NONE, -1);
+        rrdcontext_recalculate_host_retention(host, RRD_FLAG_NONE, false);
 
         // calculate version hash and pack all the messages together in one go
         our_version_hash = rrdcontext_version_hash_with_callback(host, rrdcontext_message_send_unsafe, true, bundle);
@@ -1965,11 +1691,11 @@ void rrdcontext_hub_checkpoint_command(void *ptr) {
 #endif
     }
 
-    internal_error(true, "RRDCONTEXT: host '%s' enabling streaming of contexts", host->hostname);
+    internal_error(true, "RRDCONTEXT: host '%s' enabling streaming of contexts", rrdhost_hostname(host));
     rrdhost_flag_set(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS);
     char node_str[UUID_STR_LEN];
     uuid_unparse_lower(*host->node_id, node_str);
-    log_access("ACLK REQ [%s (%s)]: STREAM CONTEXTS ENABLED", node_str, host->hostname);
+    log_access("ACLK REQ [%s (%s)]: STREAM CONTEXTS ENABLED", node_str, rrdhost_hostname(host));
 }
 
 void rrdcontext_hub_stop_streaming_command(void *ptr) {
@@ -1994,12 +1720,12 @@ void rrdcontext_hub_stop_streaming_command(void *ptr) {
 
     if(!rrdhost_flag_check(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS)) {
         error("RRDCONTEXT: received stop streaming command for claim id '%s', node id '%s', but node '%s' does not have active context streaming. Ignoring command.",
-              cmd->claim_id, cmd->node_id, host->hostname);
+              cmd->claim_id, cmd->node_id, rrdhost_hostname(host));
 
         return;
     }
 
-    internal_error(true, "RRDCONTEXT: host '%s' disabling streaming of contexts", host->hostname);
+    internal_error(true, "RRDCONTEXT: host '%s' disabling streaming of contexts", rrdhost_hostname(host));
     rrdhost_flag_clear(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS);
 }
 
@@ -2021,7 +1747,8 @@ struct rrdcontext_to_json {
     RRD_FLAGS combined_flags;
 };
 
-static inline int rrdmetric_to_json_callback(const char *id, void *value, void *data) {
+static inline int rrdmetric_to_json_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *id = dictionary_acquired_item_name(item);
     struct rrdcontext_to_json * t = data;
     RRDMETRIC *rm = value;
     BUFFER *wb = t->wb;
@@ -2029,7 +1756,7 @@ static inline int rrdmetric_to_json_callback(const char *id, void *value, void *
     time_t after = t->after;
     time_t before = t->before;
 
-    if((rm->flags & RRD_FLAG_DELETED) && !(options & RRDCONTEXT_OPTION_SHOW_DELETED))
+    if(unlikely(rrd_flag_is_deleted(rm) && !(options & RRDCONTEXT_OPTION_SHOW_DELETED)))
         return 0;
 
     if(after && (!rm->last_time_t || after > rm->last_time_t))
@@ -2047,13 +1774,13 @@ static inline int rrdmetric_to_json_callback(const char *id, void *value, void *
         buffer_strcat(wb, ",\n");
         t->combined_first_time_t = MIN(t->combined_first_time_t, rm->first_time_t);
         t->combined_last_time_t = MAX(t->combined_last_time_t, rm->last_time_t);
-        t->combined_flags |= rm->flags;
+        t->combined_flags |= rrd_flags_get(rm);
     }
     else {
         buffer_strcat(wb, "\n");
         t->combined_first_time_t = rm->first_time_t;
         t->combined_last_time_t = rm->last_time_t;
-        t->combined_flags = rm->flags;
+        t->combined_flags = rrd_flags_get(rm);
     }
 
     buffer_sprintf(wb, "\t\t\t\t\t\t\"%s\": {", id);
@@ -2066,25 +1793,25 @@ static inline int rrdmetric_to_json_callback(const char *id, void *value, void *
 
     buffer_sprintf(wb,
                    "\n\t\t\t\t\t\t\t\"name\":\"%s\""
-                   ",\n\t\t\t\t\t\t\t\"first_time_t\":%ld"
-                   ",\n\t\t\t\t\t\t\t\"last_time_t\":%ld"
+                   ",\n\t\t\t\t\t\t\t\"first_time_t\":%lld"
+                   ",\n\t\t\t\t\t\t\t\"last_time_t\":%lld"
                    ",\n\t\t\t\t\t\t\t\"collected\":%s"
                    , string2str(rm->name)
-                   , rm->first_time_t
-                   , rrd_flag_is_collected(rm) ? t->now : rm->last_time_t
-                   , rm->flags & RRD_FLAG_COLLECTED ? "true" : "false"
+                   , (long long)rm->first_time_t
+                   , rrd_flag_is_collected(rm) ? (long long)t->now : (long long)rm->last_time_t
+                   , rrd_flag_is_collected(rm) ? "true" : "false"
                    );
 
     if(options & RRDCONTEXT_OPTION_SHOW_DELETED) {
         buffer_sprintf(wb,
                        ",\n\t\t\t\t\t\t\t\"deleted\":%s"
-                       , rm->flags & RRD_FLAG_DELETED ? "true" : "false"
+                       , rrd_flag_is_deleted(rm) ? "true" : "false"
         );
     }
 
     if(options & RRDCONTEXT_OPTION_SHOW_FLAGS) {
         buffer_strcat(wb, ",\n\t\t\t\t\t\t\t\"flags\":\"");
-        rrd_flags_to_buffer(rm->flags, wb);
+        rrd_flags_to_buffer(rrd_flags_get(rm), wb);
         buffer_strcat(wb, "\"");
     }
 
@@ -2093,7 +1820,9 @@ static inline int rrdmetric_to_json_callback(const char *id, void *value, void *
     return 1;
 }
 
-static inline int rrdinstance_to_json_callback(const char *id, void *value, void *data) {
+static inline int rrdinstance_to_json_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *id = dictionary_acquired_item_name(item);
+
     struct rrdcontext_to_json *t_parent = data;
     RRDINSTANCE *ri = value;
     BUFFER *wb = t_parent->wb;
@@ -2102,7 +1831,7 @@ static inline int rrdinstance_to_json_callback(const char *id, void *value, void
     time_t before = t_parent->before;
     bool has_filter = t_parent->chart_label_key || t_parent->chart_labels_filter || t_parent->chart_dimensions;
 
-    if((ri->flags & RRD_FLAG_DELETED) && !(options & RRDCONTEXT_OPTION_SHOW_DELETED))
+    if(unlikely(rrd_flag_is_deleted(ri) && !(options & RRDCONTEXT_OPTION_SHOW_DELETED)))
         return 0;
 
     if(after && (!ri->last_time_t || after > ri->last_time_t))
@@ -2119,7 +1848,7 @@ static inline int rrdinstance_to_json_callback(const char *id, void *value, void
 
     time_t first_time_t = ri->first_time_t;
     time_t last_time_t = ri->last_time_t;
-    RRD_FLAGS flags = ri->flags;
+    RRD_FLAGS flags = rrd_flags_get(ri);
 
     BUFFER *wb_metrics = NULL;
     if(options & RRDCONTEXT_OPTION_SHOW_METRICS || t_parent->chart_dimensions) {
@@ -2179,8 +1908,8 @@ static inline int rrdinstance_to_json_callback(const char *id, void *value, void
                    ",\n\t\t\t\t\t\"chart_type\":\"%s\""
                    ",\n\t\t\t\t\t\"priority\":%u"
                    ",\n\t\t\t\t\t\"update_every\":%d"
-                   ",\n\t\t\t\t\t\"first_time_t\":%ld"
-                   ",\n\t\t\t\t\t\"last_time_t\":%ld"
+                   ",\n\t\t\t\t\t\"first_time_t\":%lld"
+                   ",\n\t\t\t\t\t\"last_time_t\":%lld"
                    ",\n\t\t\t\t\t\"collected\":%s"
                    , string2str(ri->name)
                    , string2str(ri->rc->id)
@@ -2190,25 +1919,25 @@ static inline int rrdinstance_to_json_callback(const char *id, void *value, void
                    , rrdset_type_name(ri->chart_type)
                    , ri->priority
                    , ri->update_every
-                   , first_time_t
-                   , (flags & RRD_FLAG_COLLECTED) ? t_parent->now : last_time_t
+                   , (long long)first_time_t
+                   , (flags & RRD_FLAG_COLLECTED) ? (long long)t_parent->now : (long long)last_time_t
                    , (flags & RRD_FLAG_COLLECTED) ? "true" : "false"
     );
 
     if(options & RRDCONTEXT_OPTION_SHOW_DELETED) {
         buffer_sprintf(wb,
                        ",\n\t\t\t\t\t\"deleted\":%s"
-                       , (ri->flags & RRD_FLAG_DELETED) ? "true" : "false"
+                       , rrd_flag_is_deleted(ri) ? "true" : "false"
         );
     }
 
     if(options & RRDCONTEXT_OPTION_SHOW_FLAGS) {
         buffer_strcat(wb, ",\n\t\t\t\t\t\"flags\":\"");
-        rrd_flags_to_buffer(ri->flags, wb);
+        rrd_flags_to_buffer(rrd_flags_get(ri), wb);
         buffer_strcat(wb, "\"");
     }
 
-    if(options & RRDCONTEXT_OPTION_SHOW_LABELS && ri->rrdlabels && dictionary_stats_entries(ri->rrdlabels)) {
+    if(options & RRDCONTEXT_OPTION_SHOW_LABELS && ri->rrdlabels && dictionary_entries(ri->rrdlabels)) {
         buffer_sprintf(wb, ",\n\t\t\t\t\t\"labels\": {\n");
         rrdlabels_to_buffer(ri->rrdlabels, wb, "\t\t\t\t\t\t", ":", "\"", ",\n", NULL, NULL, NULL, NULL);
         buffer_strcat(wb, "\n\t\t\t\t\t}");
@@ -2227,7 +1956,8 @@ static inline int rrdinstance_to_json_callback(const char *id, void *value, void
     return 1;
 }
 
-static inline int rrdcontext_to_json_callback(const char *id, void *value, void *data) {
+static inline int rrdcontext_to_json_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *id = dictionary_acquired_item_name(item);
     struct rrdcontext_to_json *t_parent = data;
     RRDCONTEXT *rc = value;
     BUFFER *wb = t_parent->wb;
@@ -2236,14 +1966,14 @@ static inline int rrdcontext_to_json_callback(const char *id, void *value, void
     time_t before = t_parent->before;
     bool has_filter = t_parent->chart_label_key || t_parent->chart_labels_filter || t_parent->chart_dimensions;
 
-    if(unlikely((rc->flags & RRD_FLAG_HIDDEN) && !(options & RRDCONTEXT_OPTION_SHOW_HIDDEN)))
+    if(unlikely(rrd_flag_check(rc, RRD_FLAG_HIDDEN) && !(options & RRDCONTEXT_OPTION_SHOW_HIDDEN)))
         return 0;
 
-    if((rc->flags & RRD_FLAG_DELETED) && !(options & RRDCONTEXT_OPTION_SHOW_DELETED))
+    if(unlikely(rrd_flag_is_deleted(rc) && !(options & RRDCONTEXT_OPTION_SHOW_DELETED)))
         return 0;
 
     if(options & RRDCONTEXT_OPTION_DEEPSCAN)
-        rrdcontext_recalculate_context_retention(rc, RRD_FLAG_NONE, -1);
+        rrdcontext_recalculate_context_retention(rc, RRD_FLAG_NONE, false);
 
     if(after && (!rc->last_time_t || after > rc->last_time_t))
         return 0;
@@ -2253,7 +1983,7 @@ static inline int rrdcontext_to_json_callback(const char *id, void *value, void
 
     time_t first_time_t = rc->first_time_t;
     time_t last_time_t = rc->last_time_t;
-    RRD_FLAGS flags = rc->flags;
+    RRD_FLAGS flags = rrd_flags_get(rc);
 
     BUFFER *wb_instances = NULL;
     if((options & (RRDCONTEXT_OPTION_SHOW_LABELS|RRDCONTEXT_OPTION_SHOW_INSTANCES|RRDCONTEXT_OPTION_SHOW_METRICS))
@@ -2304,29 +2034,29 @@ static inline int rrdcontext_to_json_callback(const char *id, void *value, void
                    ",\n\t\t\t\"family\":\"%s\""
                    ",\n\t\t\t\"chart_type\":\"%s\""
                    ",\n\t\t\t\"priority\":%u"
-                   ",\n\t\t\t\"first_time_t\":%ld"
-                   ",\n\t\t\t\"last_time_t\":%ld"
+                   ",\n\t\t\t\"first_time_t\":%lld"
+                   ",\n\t\t\t\"last_time_t\":%lld"
                    ",\n\t\t\t\"collected\":%s"
                    , string2str(rc->title)
                    , string2str(rc->units)
                    , string2str(rc->family)
                    , rrdset_type_name(rc->chart_type)
                    , rc->priority
-                   , first_time_t
-                   , (flags & RRD_FLAG_COLLECTED) ? t_parent->now : last_time_t
+                   , (long long)first_time_t
+                   , (flags & RRD_FLAG_COLLECTED) ? (long long)t_parent->now : (long long)last_time_t
                    , (flags & RRD_FLAG_COLLECTED) ? "true" : "false"
                    );
 
     if(options & RRDCONTEXT_OPTION_SHOW_DELETED) {
         buffer_sprintf(wb,
                        ",\n\t\t\t\"deleted\":%s"
-                       , (rc->flags & RRD_FLAG_DELETED) ? "true" : "false"
+                       , rrd_flag_is_deleted(rc) ? "true" : "false"
         );
     }
 
     if(options & RRDCONTEXT_OPTION_SHOW_FLAGS) {
         buffer_strcat(wb, ",\n\t\t\t\"flags\":\"");
-        rrd_flags_to_buffer(rc->flags, wb);
+        rrd_flags_to_buffer(rrd_flags_get(rc), wb);
         buffer_strcat(wb, "\"");
     }
 
@@ -2339,14 +2069,29 @@ static inline int rrdcontext_to_json_callback(const char *id, void *value, void
                        ",\n\t\t\t\"last_queued\":%llu"
                        ",\n\t\t\t\"scheduled_dispatch\":%llu"
                        ",\n\t\t\t\"last_dequeued\":%llu"
+                       ",\n\t\t\t\"dispatches\":%zu"
                        ",\n\t\t\t\"hub_version\":%"PRIu64""
                        ",\n\t\t\t\"version\":%"PRIu64""
                        , rc->queue.queued_ut / USEC_PER_SEC
                        , rc->queue.scheduled_dispatch_ut / USEC_PER_SEC
                        , rc->queue.dequeued_ut / USEC_PER_SEC
+                       , rc->queue.dispatches
                        , rc->hub.version
                        , rc->version
                        );
+
+        buffer_strcat(wb, ",\n\t\t\t\"pp_reasons\":\"");
+        rrd_reasons_to_buffer(rc->pp.queued_flags, wb);
+        buffer_strcat(wb, "\"");
+
+        buffer_sprintf(wb,
+                       ",\n\t\t\t\"pp_last_queued\":%llu"
+                       ",\n\t\t\t\"pp_last_dequeued\":%llu"
+                       ",\n\t\t\t\"pp_executed\":%zu"
+                       , rc->pp.queued_ut / USEC_PER_SEC
+                       , rc->pp.dequeued_ut / USEC_PER_SEC
+                       , rc->pp.executions
+        );
     }
 
     rrdcontext_unlock(rc);
@@ -2365,18 +2110,18 @@ static inline int rrdcontext_to_json_callback(const char *id, void *value, void
 }
 
 int rrdcontext_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before, RRDCONTEXT_TO_JSON_OPTIONS options, const char *context, SIMPLE_PATTERN *chart_label_key, SIMPLE_PATTERN *chart_labels_filter, SIMPLE_PATTERN *chart_dimensions) {
+    if(!host->rrdctx) {
+        error("%s(): request for host '%s' that does not have rrdcontexts initialized.", __FUNCTION__, rrdhost_hostname(host));
+        return HTTP_RESP_NOT_FOUND;
+    }
+
     RRDCONTEXT_ACQUIRED *rca = (RRDCONTEXT_ACQUIRED *)dictionary_get_and_acquire_item((DICTIONARY *)host->rrdctx, context);
     if(!rca) return HTTP_RESP_NOT_FOUND;
 
     RRDCONTEXT *rc = rrdcontext_acquired_value(rca);
 
-    if(after != 0 && before != 0) {
-        long long after_wanted = after;
-        long long before_wanted = before;
-        rrdr_relative_window_to_absolute(&after_wanted, &before_wanted);
-        after = after_wanted;
-        before = before_wanted;
-    }
+    if(after != 0 && before != 0)
+        rrdr_relative_window_to_absolute(&after, &before);
 
     struct rrdcontext_to_json t_contexts = {
         .wb = wb,
@@ -2389,7 +2134,7 @@ int rrdcontext_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before, R
         .written = 0,
         .now = now_realtime_sec(),
     };
-    rrdcontext_to_json_callback(context, rc, &t_contexts);
+    rrdcontext_to_json_callback((DICTIONARY_ITEM *)rca, rc, &t_contexts);
 
     rrdcontext_release(rca);
 
@@ -2400,25 +2145,25 @@ int rrdcontext_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before, R
 }
 
 int rrdcontexts_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before, RRDCONTEXT_TO_JSON_OPTIONS options, SIMPLE_PATTERN *chart_label_key, SIMPLE_PATTERN *chart_labels_filter, SIMPLE_PATTERN *chart_dimensions) {
+    if(!host->rrdctx) {
+        error("%s(): request for host '%s' that does not have rrdcontexts initialized.", __FUNCTION__, rrdhost_hostname(host));
+        return HTTP_RESP_NOT_FOUND;
+    }
+
     char node_uuid[UUID_STR_LEN] = "";
 
     if(host->node_id)
         uuid_unparse(*host->node_id, node_uuid);
 
-    if(after != 0 && before != 0) {
-        long long after_wanted = after;
-        long long before_wanted = before;
-        rrdr_relative_window_to_absolute(&after_wanted, &before_wanted);
-        after = after_wanted;
-        before = before_wanted;
-    }
+    if(after != 0 && before != 0)
+        rrdr_relative_window_to_absolute(&after, &before);
 
     buffer_sprintf(wb, "{\n"
                           "\t\"hostname\": \"%s\""
                        ",\n\t\"machine_guid\": \"%s\""
                        ",\n\t\"node_id\": \"%s\""
                        ",\n\t\"claim_id\": \"%s\""
-                   , host->hostname
+                   , rrdhost_hostname(host)
                    , host->machine_guid
                    , node_uuid
                    , host->aclk_state.claimed_id ? host->aclk_state.claimed_id : ""
@@ -2426,7 +2171,7 @@ int rrdcontexts_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before,
 
     if(options & RRDCONTEXT_OPTION_SHOW_LABELS) {
         buffer_sprintf(wb, ",\n\t\"host_labels\": {\n");
-        rrdlabels_to_buffer(host->host_labels, wb, "\t\t", ":", "\"", ",\n", NULL, NULL, NULL, NULL);
+        rrdlabels_to_buffer(host->rrdlabels, wb, "\t\t", ":", "\"", ",\n", NULL, NULL, NULL, NULL);
         buffer_strcat(wb, "\n\t}");
     }
 
@@ -2451,6 +2196,684 @@ int rrdcontexts_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before,
 }
 
 // ----------------------------------------------------------------------------
+// weights API
+
+static void metric_entry_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *data __maybe_unused) {
+    struct metric_entry *t = value;
+    t->rca = rrdcontext_acquired_dup(t->rca);
+    t->ria = rrdinstance_acquired_dup(t->ria);
+    t->rma = rrdmetric_acquired_dup(t->rma);
+}
+static void metric_entry_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *data __maybe_unused) {
+    struct metric_entry *t = value;
+    rrdcontext_release(t->rca);
+    rrdinstance_release(t->ria);
+    rrdmetric_release(t->rma);
+}
+static bool metric_entry_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *old_value __maybe_unused, void *new_value __maybe_unused, void *data __maybe_unused) {
+    fatal("RRDCONTEXT: %s() detected a conflict on a metric pointer!", __FUNCTION__);
+    return false;
+}
+
+DICTIONARY *rrdcontext_all_metrics_to_dict(RRDHOST *host, SIMPLE_PATTERN *contexts) {
+    if(!host || !host->rrdctx)
+        return NULL;
+
+    DICTIONARY *dict = dictionary_create(DICT_OPTION_SINGLE_THREADED|DICT_OPTION_DONT_OVERWRITE_VALUE);
+    dictionary_register_insert_callback(dict, metric_entry_insert_callback, NULL);
+    dictionary_register_delete_callback(dict, metric_entry_delete_callback, NULL);
+    dictionary_register_conflict_callback(dict, metric_entry_conflict_callback, NULL);
+
+    RRDCONTEXT *rc;
+    dfe_start_reentrant((DICTIONARY *)host->rrdctx, rc) {
+        if(rrd_flag_is_deleted(rc))
+            continue;
+
+        if(contexts && !simple_pattern_matches(contexts, string2str(rc->id)))
+            continue;
+
+        RRDINSTANCE *ri;
+        dfe_start_read(rc->rrdinstances, ri) {
+            if(rrd_flag_is_deleted(ri))
+                continue;
+
+            RRDMETRIC *rm;
+            dfe_start_read(ri->rrdmetrics, rm) {
+                if(rrd_flag_is_deleted(rm))
+                    continue;
+
+                struct metric_entry tmp = {
+                    .rca = (RRDCONTEXT_ACQUIRED *)rc_dfe.item,
+                    .ria = (RRDINSTANCE_ACQUIRED *)ri_dfe.item,
+                    .rma = (RRDMETRIC_ACQUIRED *)rm_dfe.item,
+                };
+
+                char buffer[20 + 1];
+                ssize_t len = snprintfz(buffer, 20, "%p", rm);
+                dictionary_set_advanced(dict, buffer, len + 1, &tmp, sizeof(struct metric_entry), NULL);
+            }
+            dfe_done(rm);
+        }
+        dfe_done(ri);
+    }
+    dfe_done(rc);
+
+    return dict;
+}
+
+// ----------------------------------------------------------------------------
+// query API
+
+typedef struct query_target_locals {
+    time_t start_s;
+
+    QUERY_TARGET *qt;
+
+    RRDSET *st;
+
+    const char *hosts;
+    const char *contexts;
+    const char *charts;
+    const char *dimensions;
+    const char *chart_label_key;
+    const char *charts_labels_filter;
+
+    long long after;
+    long long before;
+    bool match_ids;
+    bool match_names;
+
+    RRDHOST *host;
+    RRDCONTEXT_ACQUIRED *rca;
+    RRDINSTANCE_ACQUIRED *ria;
+
+    size_t metrics_skipped_due_to_not_matching_timeframe;
+} QUERY_TARGET_LOCALS;
+
+static __thread QUERY_TARGET thread_query_target = {};
+void query_target_release(QUERY_TARGET *qt) {
+    if(unlikely(!qt)) return;
+    if(unlikely(!qt->used)) return;
+
+    simple_pattern_free(qt->hosts.pattern);
+    qt->hosts.pattern = NULL;
+
+    simple_pattern_free(qt->contexts.pattern);
+    qt->contexts.pattern = NULL;
+
+    simple_pattern_free(qt->instances.pattern);
+    qt->instances.pattern = NULL;
+
+    simple_pattern_free(qt->instances.chart_label_key_pattern);
+    qt->instances.chart_label_key_pattern = NULL;
+
+    simple_pattern_free(qt->instances.charts_labels_filter_pattern);
+    qt->instances.charts_labels_filter_pattern = NULL;
+
+    simple_pattern_free(qt->query.pattern);
+    qt->query.pattern = NULL;
+
+    // release the query
+    for(size_t i = 0, used = qt->query.used; i < used ;i++) {
+        string_freez(qt->query.array[i].dimension.id);
+        qt->query.array[i].dimension.id = NULL;
+
+        string_freez(qt->query.array[i].dimension.name);
+        qt->query.array[i].dimension.name = NULL;
+
+        string_freez(qt->query.array[i].chart.id);
+        qt->query.array[i].chart.id = NULL;
+
+        string_freez(qt->query.array[i].chart.name);
+        qt->query.array[i].chart.name = NULL;
+
+        for(size_t tier = 0; tier < storage_tiers ;tier++) {
+            if(qt->query.array[i].tiers[tier].db_metric_handle) {
+                STORAGE_ENGINE *eng = qt->query.array[i].tiers[tier].eng;
+                eng->api.metric_release(qt->query.array[i].tiers[tier].db_metric_handle);
+                qt->query.array[i].tiers[tier].db_metric_handle = NULL;
+            }
+        }
+    }
+
+    // release the metrics
+    for(size_t i = 0, used = qt->metrics.used; i < used ;i++) {
+        rrdmetric_release(qt->metrics.array[i]);
+        qt->metrics.array[i] = NULL;
+    }
+
+    // release the instances
+    for(size_t i = 0, used = qt->instances.used; i < used ;i++) {
+        rrdinstance_release(qt->instances.array[i]);
+        qt->instances.array[i] = NULL;
+    }
+
+    // release the contexts
+    for(size_t i = 0, used = qt->contexts.used; i < used ;i++) {
+        rrdcontext_release(qt->contexts.array[i]);
+        qt->contexts.array[i] = NULL;
+    }
+
+    // release the hosts
+    for(size_t i = 0, used = qt->hosts.used; i < used ;i++) {
+        qt->hosts.array[i] = NULL;
+    }
+
+    qt->query.used = 0;
+    qt->metrics.used = 0;
+    qt->instances.used = 0;
+    qt->contexts.used = 0;
+    qt->hosts.used = 0;
+
+    qt->db.minimum_latest_update_every = 0;
+    qt->db.first_time_t = 0;
+    qt->db.last_time_t = 0;
+
+    qt->id[0] = '\0';
+
+    qt->used = false;
+}
+void query_target_free(void) {
+    if(thread_query_target.used)
+        query_target_release(&thread_query_target);
+
+    freez(thread_query_target.query.array);
+    thread_query_target.query.array = NULL;
+    thread_query_target.query.size = 0;
+
+    freez(thread_query_target.metrics.array);
+    thread_query_target.metrics.array = NULL;
+    thread_query_target.metrics.size = 0;
+
+    freez(thread_query_target.instances.array);
+    thread_query_target.instances.array = NULL;
+    thread_query_target.instances.size = 0;
+
+    freez(thread_query_target.contexts.array);
+    thread_query_target.contexts.array = NULL;
+    thread_query_target.contexts.size = 0;
+
+    freez(thread_query_target.hosts.array);
+    thread_query_target.hosts.array = NULL;
+    thread_query_target.hosts.size = 0;
+}
+
+static void query_target_add_metric(QUERY_TARGET_LOCALS *qtl, RRDMETRIC_ACQUIRED *rma, RRDINSTANCE *ri,
+                                    bool queryable_instance) {
+    QUERY_TARGET *qt = qtl->qt;
+
+    RRDMETRIC *rm = rrdmetric_acquired_value(rma);
+    if(rrd_flag_is_deleted(rm))
+        return;
+
+    if(qt->metrics.used == qt->metrics.size) {
+        qt->metrics.size = (qt->metrics.size) ? qt->metrics.size * 2 : 1;
+        qt->metrics.array = reallocz(qt->metrics.array, qt->metrics.size * sizeof(RRDMETRIC_ACQUIRED *));
+    }
+    qt->metrics.array[qt->metrics.used++] = rrdmetric_acquired_dup(rma);
+
+    if(!queryable_instance)
+        return;
+
+    time_t common_first_time_t = 0;
+    time_t common_last_time_t = 0;
+    time_t common_update_every = 0;
+    size_t tiers_added = 0;
+    struct {
+        STORAGE_ENGINE *eng;
+        STORAGE_METRIC_HANDLE *db_metric_handle;
+        time_t db_first_time_t;
+        time_t db_last_time_t;
+        time_t db_update_every;
+    } tier_retention[storage_tiers];
+
+    for (size_t tier = 0; tier < storage_tiers; tier++) {
+        STORAGE_ENGINE *eng = qtl->host->db[tier].eng;
+        tier_retention[tier].eng = eng;
+        tier_retention[tier].db_update_every = (time_t) (qtl->host->db[tier].tier_grouping * ri->update_every);
+
+        if(rm->rrddim && rm->rrddim->tiers[tier] && rm->rrddim->tiers[tier]->db_metric_handle)
+            tier_retention[tier].db_metric_handle = eng->api.metric_dup(rm->rrddim->tiers[tier]->db_metric_handle);
+        else
+            tier_retention[tier].db_metric_handle = eng->api.metric_get(qtl->host->db[tier].instance, &rm->uuid, NULL);
+
+        if(tier_retention[tier].db_metric_handle) {
+            tier_retention[tier].db_first_time_t = tier_retention[tier].eng->api.query_ops.oldest_time(tier_retention[tier].db_metric_handle);
+            tier_retention[tier].db_last_time_t = tier_retention[tier].eng->api.query_ops.latest_time(tier_retention[tier].db_metric_handle);
+
+            if(!common_first_time_t)
+                common_first_time_t = tier_retention[tier].db_first_time_t;
+            else if(tier_retention[tier].db_first_time_t)
+                common_first_time_t = MIN(common_first_time_t, tier_retention[tier].db_first_time_t);
+
+            if(!common_last_time_t)
+                common_last_time_t = tier_retention[tier].db_last_time_t;
+            else
+                common_last_time_t = MAX(common_last_time_t, tier_retention[tier].db_last_time_t);
+
+            if(!common_update_every)
+                common_update_every = tier_retention[tier].db_update_every;
+            else if(tier_retention[tier].db_update_every)
+                common_update_every = MIN(common_update_every, tier_retention[tier].db_update_every);
+
+            tiers_added++;
+        }
+        else {
+            tier_retention[tier].db_first_time_t = 0;
+            tier_retention[tier].db_last_time_t = 0;
+            tier_retention[tier].db_update_every = 0;
+        }
+    }
+
+    bool release_retention = true;
+    bool timeframe_matches =
+            (tiers_added
+            && (common_first_time_t - common_update_every * 2) <= qt->window.before
+            && (common_last_time_t + common_update_every * 2) >= qt->window.after
+            ) ? true : false;
+
+    if(timeframe_matches) {
+        RRDR_DIMENSION_FLAGS options = RRDR_DIMENSION_DEFAULT;
+
+        if (rrd_flag_check(rm, RRD_FLAG_HIDDEN)
+            || (rm->rrddim && rrddim_option_check(rm->rrddim, RRDDIM_OPTION_HIDDEN))) {
+            options |= RRDR_DIMENSION_HIDDEN;
+            options &= ~RRDR_DIMENSION_SELECTED;
+        }
+
+        if (qt->query.pattern) {
+            // we have a dimensions pattern
+            // lets see if this dimension is selected
+
+            if ((qtl->match_ids   && simple_pattern_matches(qt->query.pattern, string2str(rm->id)))
+             || (qtl->match_names && simple_pattern_matches(qt->query.pattern, string2str(rm->name)))
+                    ) {
+                // it matches the pattern
+                options |= (RRDR_DIMENSION_SELECTED | RRDR_DIMENSION_NONZERO);
+                options &= ~RRDR_DIMENSION_HIDDEN;
+            }
+            else {
+                // it does not match the pattern
+                options |= RRDR_DIMENSION_HIDDEN;
+                options &= ~RRDR_DIMENSION_SELECTED;
+            }
+        }
+        else {
+            // we don't have a dimensions pattern
+            // so this is a selected dimension
+            // if it is not hidden
+            if(!(options & RRDR_DIMENSION_HIDDEN))
+                options |= RRDR_DIMENSION_SELECTED;
+        }
+
+        if((options & RRDR_DIMENSION_HIDDEN) && (options & RRDR_DIMENSION_SELECTED))
+            options &= ~RRDR_DIMENSION_HIDDEN;
+
+        if(!(options & RRDR_DIMENSION_HIDDEN) || (qt->request.options & RRDR_OPTION_PERCENTAGE)) {
+            // we have a non-hidden dimension
+            // let's add it to the query metrics
+
+            if(ri->rrdset)
+                ri->rrdset->last_accessed_time = qtl->start_s;
+
+            if (qt->query.used == qt->query.size) {
+                qt->query.size = (qt->query.size) ? qt->query.size * 2 : 1;
+                qt->query.array = reallocz(qt->query.array, qt->query.size * sizeof(QUERY_METRIC));
+            }
+            QUERY_METRIC *qm = &qt->query.array[qt->query.used++];
+
+            qm->dimension.options = options;
+
+            qm->link.host = qtl->host;
+            qm->link.rca = qtl->rca;
+            qm->link.ria = qtl->ria;
+            qm->link.rma = rma;
+
+            qm->chart.id = string_dup(ri->id);
+            qm->chart.name = string_dup(ri->name);
+
+            qm->dimension.id = string_dup(rm->id);
+            qm->dimension.name = string_dup(rm->name);
+
+            if (!qt->db.first_time_t || common_first_time_t < qt->db.first_time_t)
+                qt->db.first_time_t = common_first_time_t;
+
+            if (!qt->db.last_time_t || common_last_time_t > qt->db.last_time_t)
+                qt->db.last_time_t = common_last_time_t;
+
+            for (size_t tier = 0; tier < storage_tiers; tier++) {
+                qm->tiers[tier].eng = tier_retention[tier].eng;
+                qm->tiers[tier].db_metric_handle = tier_retention[tier].db_metric_handle;
+                qm->tiers[tier].db_first_time_t = tier_retention[tier].db_first_time_t;
+                qm->tiers[tier].db_last_time_t = tier_retention[tier].db_last_time_t;
+                qm->tiers[tier].db_update_every = tier_retention[tier].db_update_every;
+            }
+            release_retention = false;
+        }
+    }
+    else
+        qtl->metrics_skipped_due_to_not_matching_timeframe++;
+
+    if(release_retention) {
+        // cleanup anything we allocated to the retention we will not use
+        for(size_t tier = 0; tier < storage_tiers ;tier++) {
+            if (tier_retention[tier].db_metric_handle)
+                tier_retention[tier].eng->api.metric_release(tier_retention[tier].db_metric_handle);
+        }
+    }
+}
+
+static void query_target_add_instance(QUERY_TARGET_LOCALS *qtl, RRDINSTANCE_ACQUIRED *ria, bool queryable_instance) {
+    QUERY_TARGET *qt = qtl->qt;
+
+    RRDINSTANCE *ri = rrdinstance_acquired_value(ria);
+    if(rrd_flag_is_deleted(ri))
+        return;
+
+    if(qt->instances.used == qt->instances.size) {
+        qt->instances.size = (qt->instances.size) ? qt->instances.size * 2 : 1;
+        qt->instances.array = reallocz(qt->instances.array, qt->instances.size * sizeof(RRDINSTANCE_ACQUIRED *));
+    }
+
+    qtl->ria = qt->instances.array[qt->instances.used++] = rrdinstance_acquired_dup(ria);
+
+    if(qt->db.minimum_latest_update_every == 0 || ri->update_every < qt->db.minimum_latest_update_every)
+        qt->db.minimum_latest_update_every = ri->update_every;
+
+    if(queryable_instance) {
+        if ((qt->instances.chart_label_key_pattern && !rrdlabels_match_simple_pattern_parsed(ri->rrdlabels, qt->instances.chart_label_key_pattern, ':')) ||
+            (qt->instances.charts_labels_filter_pattern && !rrdlabels_match_simple_pattern_parsed(ri->rrdlabels, qt->instances.charts_labels_filter_pattern, ':')))
+            queryable_instance = false;
+    }
+
+    size_t added = 0;
+
+    if(unlikely(qt->request.rma)) {
+        query_target_add_metric(qtl, qt->request.rma, ri, queryable_instance);
+        added++;
+    }
+    else {
+        RRDMETRIC *rm;
+        dfe_start_read(ri->rrdmetrics, rm) {
+            query_target_add_metric(qtl, (RRDMETRIC_ACQUIRED *) rm_dfe.item, ri, queryable_instance);
+            added++;
+        }
+        dfe_done(rm);
+    }
+
+    if(!added) {
+        qt->instances.used--;
+        rrdinstance_release(ria);
+    }
+}
+
+static void query_target_add_context(QUERY_TARGET_LOCALS *qtl, RRDCONTEXT_ACQUIRED *rca) {
+    QUERY_TARGET *qt = qtl->qt;
+
+    RRDCONTEXT *rc = rrdcontext_acquired_value(rca);
+    if(rrd_flag_is_deleted(rc))
+        return;
+
+    if(qt->contexts.used == qt->contexts.size) {
+        qt->contexts.size = (qt->contexts.size) ? qt->contexts.size * 2 : 1;
+        qt->contexts.array = reallocz(qt->contexts.array, qt->contexts.size * sizeof(RRDCONTEXT_ACQUIRED *));
+    }
+    qtl->rca = qt->contexts.array[qt->contexts.used++] = rrdcontext_acquired_dup(rca);
+
+    size_t added = 0;
+    if(unlikely(qt->request.ria)) {
+        query_target_add_instance(qtl, qt->request.ria, true);
+        added++;
+    }
+    else if(unlikely(qtl->st && qtl->st->rrdcontext == rca && qtl->st->rrdinstance)) {
+        query_target_add_instance(qtl, qtl->st->rrdinstance, true);
+        added++;
+    }
+    else {
+        RRDINSTANCE *ri;
+        dfe_start_read(rc->rrdinstances, ri) {
+            bool queryable_instance = false;
+            if(!qt->instances.pattern
+                || (qtl->match_ids   && simple_pattern_matches(qt->instances.pattern, string2str(ri->id)))
+                || (qtl->match_names && simple_pattern_matches(qt->instances.pattern, string2str(ri->name)))
+                )
+                queryable_instance = true;
+
+            query_target_add_instance(qtl, (RRDINSTANCE_ACQUIRED *)ri_dfe.item, queryable_instance);
+            added++;
+        }
+        dfe_done(ri);
+    }
+
+    if(!added) {
+        qt->contexts.used--;
+        rrdcontext_release(rca);
+    }
+}
+
+static void query_target_add_host(QUERY_TARGET_LOCALS *qtl, RRDHOST *host) {
+    QUERY_TARGET *qt = qtl->qt;
+
+    if(qt->hosts.used == qt->hosts.size) {
+        qt->hosts.size = (qt->hosts.size) ? qt->hosts.size * 2 : 1;
+        qt->hosts.array = reallocz(qt->hosts.array, qt->hosts.size * sizeof(RRDHOST *));
+    }
+    qtl->host = qt->hosts.array[qt->hosts.used++] = host;
+
+    // is the chart given valid?
+    if(unlikely(qtl->st && (!qtl->st->rrdinstance || !qtl->st->rrdcontext))) {
+        error("QUERY TARGET: RRDSET '%s' given, because it is not linked to rrdcontext structures. Switching to context query.", rrdset_name(qtl->st));
+
+        if(!is_valid_sp(qtl->charts))
+            qtl->charts = rrdset_name(qtl->st);
+
+        qtl->st = NULL;
+    }
+
+    size_t added = 0;
+    if(unlikely(qt->request.rca)) {
+        query_target_add_context(qtl, qt->request.rca);
+        added++;
+    }
+    else if(unlikely(qtl->st)) {
+        // single chart data queries
+        query_target_add_context(qtl, qtl->st->rrdcontext);
+        added++;
+    }
+    else {
+        // context pattern queries
+        RRDCONTEXT_ACQUIRED *rca = (RRDCONTEXT_ACQUIRED *)dictionary_get_and_acquire_item((DICTIONARY *)qtl->host->rrdctx, qtl->contexts);
+        if(likely(rca)) {
+            // we found it!
+            query_target_add_context(qtl, rca);
+            rrdcontext_release(rca);
+            added++;
+        }
+        else {
+            // Probably it is a pattern, we need to search for it...
+            RRDCONTEXT *rc;
+            dfe_start_read((DICTIONARY *)qtl->host->rrdctx, rc) {
+                if(qt->contexts.pattern && !simple_pattern_matches(qt->contexts.pattern, string2str(rc->id)))
+                    continue;
+
+                query_target_add_context(qtl, (RRDCONTEXT_ACQUIRED *)rc_dfe.item);
+                added++;
+            }
+            dfe_done(rc);
+        }
+    }
+
+    if(!added) {
+        qt->hosts.used--;
+    }
+}
+
+void query_target_generate_name(QUERY_TARGET *qt) {
+    char options_buffer[100 + 1];
+    web_client_api_request_v1_data_options_to_string(options_buffer, 100, qt->request.options);
+
+    char resampling_buffer[20 + 1] = "";
+    if(qt->request.resampling_time > 1)
+        snprintfz(resampling_buffer, 20, "/resampling:%lld", (long long)qt->request.resampling_time);
+
+    char tier_buffer[20 + 1] = "";
+    if(qt->request.options & RRDR_OPTION_SELECTED_TIER)
+        snprintfz(tier_buffer, 20, "/tier:%zu", qt->request.tier);
+
+    if(qt->request.st)
+        snprintfz(qt->id, MAX_QUERY_TARGET_ID_LENGTH, "chart://host:%s/instance:%s/dimensions:%s/after:%lld/before:%lld/points:%zu/group:%s%s/options:%s%s%s"
+                  , rrdhost_hostname(qt->request.st->rrdhost)
+                  , rrdset_name(qt->request.st)
+                  , (qt->request.dimensions) ? qt->request.dimensions : "*"
+                  , (long long)qt->request.after
+                  , (long long)qt->request.before
+                  , qt->request.points
+                  , web_client_api_request_v1_data_group_to_string(qt->request.group_method)
+                  , qt->request.group_options?qt->request.group_options:""
+                  , options_buffer
+                  , resampling_buffer
+                  , tier_buffer
+                  );
+    else if(qt->request.host && qt->request.rca && qt->request.ria && qt->request.rma)
+        snprintfz(qt->id, MAX_QUERY_TARGET_ID_LENGTH, "metric://host:%s/context:%s/instance:%s/dimension:%s/after:%lld/before:%lld/points:%zu/group:%s%s/options:%s%s%s"
+                , rrdhost_hostname(qt->request.host)
+                , rrdcontext_acquired_id(qt->request.rca)
+                , rrdinstance_acquired_id(qt->request.ria)
+                , rrdmetric_acquired_id(qt->request.rma)
+                , (long long)qt->request.after
+                , (long long)qt->request.before
+                , qt->request.points
+                , web_client_api_request_v1_data_group_to_string(qt->request.group_method)
+                , qt->request.group_options?qt->request.group_options:""
+                , options_buffer
+                , resampling_buffer
+                , tier_buffer
+                );
+    else
+        snprintfz(qt->id, MAX_QUERY_TARGET_ID_LENGTH, "context://host:%s/contexts:%s/instances:%s/dimensions:%s/after:%lld/before:%lld/points:%zu/group:%s%s/options:%s%s%s"
+                , (qt->request.host) ? rrdhost_hostname(qt->request.host) : ((qt->request.hosts) ? qt->request.hosts : "*")
+                , (qt->request.contexts) ? qt->request.contexts : "*"
+                , (qt->request.charts) ? qt->request.charts : "*"
+                , (qt->request.dimensions) ? qt->request.dimensions : "*"
+                , (long long)qt->request.after
+                , (long long)qt->request.before
+                , qt->request.points
+                , web_client_api_request_v1_data_group_to_string(qt->request.group_method)
+                , qt->request.group_options?qt->request.group_options:""
+                , options_buffer
+                , resampling_buffer
+                , tier_buffer
+                );
+
+    json_fix_string(qt->id);
+}
+
+QUERY_TARGET *query_target_create(QUERY_TARGET_REQUEST *qtr) {
+    QUERY_TARGET *qt = &thread_query_target;
+
+    if(qt->used)
+        fatal("QUERY TARGET: this query target is already used (%zu queries made with this QUERY_TARGET so far).", qt->queries);
+
+    qt->used = true;
+    qt->queries++;
+
+    // copy the request into query_thread_target
+    qt->request = *qtr;
+
+    query_target_generate_name(qt);
+    qt->window.after = qt->request.after;
+    qt->window.before = qt->request.before;
+    rrdr_relative_window_to_absolute(&qt->window.after, &qt->window.before);
+
+    // prepare our local variables - we need these across all these functions
+    QUERY_TARGET_LOCALS qtl = {
+        .qt = qt,
+        .start_s = now_realtime_sec(),
+        .host = qt->request.host,
+        .st = qt->request.st,
+        .hosts = qt->request.hosts,
+        .contexts = qt->request.contexts,
+        .charts = qt->request.charts,
+        .dimensions = qt->request.dimensions,
+        .chart_label_key = qt->request.chart_label_key,
+        .charts_labels_filter = qt->request.charts_labels_filter,
+    };
+
+    qt->db.minimum_latest_update_every = 0; // it will be updated by query_target_add_query()
+
+    // prepare all the patterns
+    qt->hosts.pattern = is_valid_sp(qtl.hosts) ? simple_pattern_create(qtl.hosts, ",|\t\r\n\f\v", SIMPLE_PATTERN_EXACT) : NULL;
+    qt->contexts.pattern = is_valid_sp(qtl.contexts) ? simple_pattern_create(qtl.contexts, ",|\t\r\n\f\v", SIMPLE_PATTERN_EXACT) : NULL;
+    qt->instances.pattern = is_valid_sp(qtl.charts) ? simple_pattern_create(qtl.charts, ",|\t\r\n\f\v", SIMPLE_PATTERN_EXACT) : NULL;
+    qt->query.pattern = is_valid_sp(qtl.dimensions) ? simple_pattern_create(qtl.dimensions, ",|\t\r\n\f\v", SIMPLE_PATTERN_EXACT) : NULL;
+    qt->instances.chart_label_key_pattern = is_valid_sp(qtl.chart_label_key) ? simple_pattern_create(qtl.chart_label_key, ",|\t\r\n\f\v", SIMPLE_PATTERN_EXACT) : NULL;
+    qt->instances.charts_labels_filter_pattern = is_valid_sp(qtl.charts_labels_filter) ? simple_pattern_create(qtl.charts_labels_filter, ",|\t\r\n\f\v", SIMPLE_PATTERN_EXACT) : NULL;
+
+    qtl.match_ids = qt->request.options & RRDR_OPTION_MATCH_IDS;
+    qtl.match_names = qt->request.options & RRDR_OPTION_MATCH_NAMES;
+    if(likely(!qtl.match_ids && !qtl.match_names))
+        qtl.match_ids = qtl.match_names = true;
+
+    // verify that the chart belongs to the host we are interested
+    if(qtl.st) {
+        if (!qtl.host) {
+            // It is NULL, set it ourselves.
+            qtl.host = qtl.st->rrdhost;
+        }
+        else if (unlikely(qtl.host != qtl.st->rrdhost)) {
+            // Oops! A different host!
+            error("QUERY TARGET: RRDSET '%s' given does not belong to host '%s'. Switching query host to '%s'",
+                  rrdset_name(qtl.st), rrdhost_hostname(qtl.host), rrdhost_hostname(qtl.st->rrdhost));
+            qtl.host = qtl.st->rrdhost;
+        }
+    }
+
+    if(qtl.host) {
+        // single host query
+        query_target_add_host(&qtl, qtl.host);
+        qtl.hosts = rrdhost_hostname(qtl.host);
+    }
+    else {
+        // multi host query
+        rrd_rdlock();
+        rrdhost_foreach_read(qtl.host) {
+            if(!qt->hosts.pattern || simple_pattern_matches(qt->hosts.pattern, rrdhost_hostname(qtl.host)))
+                query_target_add_host(&qtl, qtl.host);
+        }
+        rrd_unlock();
+    }
+
+    // make sure everything is good
+    if(!qt->query.used || !qt->metrics.used || !qt->instances.used || !qt->contexts.used || !qt->hosts.used) {
+        internal_error(
+                true
+                , "QUERY TARGET: query '%s' does not have all the data required. "
+                  "Matched %u hosts, %u contexts, %u instances, %u dimensions, %u metrics to query, "
+                  "%zu metrics skipped because they don't have data in the desired time-frame. "
+                  "Aborting it."
+                , qt->id
+                , qt->hosts.used
+                , qt->contexts.used
+                , qt->instances.used
+                , qt->metrics.used
+                , qt->query.used
+                , qtl.metrics_skipped_due_to_not_matching_timeframe
+                );
+
+        query_target_release(qt);
+        return NULL;
+    }
+
+    if(!query_target_calculate_window(qt)) {
+        query_target_release(qt);
+        return NULL;
+    }
+
+    return qt;
+}
+
+
+// ----------------------------------------------------------------------------
 // load from SQL
 
 static void rrdinstance_load_clabel(SQL_CLABEL_DATA *sld, void *data) {
@@ -2464,8 +2887,10 @@ static void rrdinstance_load_dimension(SQL_DIMENSION_DATA *sd, void *data) {
     RRDMETRIC trm = {
         .id = string_strdupz(sd->id),
         .name = string_strdupz(sd->name),
-        .flags = RRD_FLAG_ARCHIVED | RRD_FLAG_UPDATE_REASON_LOAD_SQL,
+        .flags = RRD_FLAG_ARCHIVED | RRD_FLAG_UPDATE_REASON_LOAD_SQL, // no need for atomic
     };
+    if(sd->hidden) trm.flags |= RRD_FLAG_HIDDEN;
+
     uuid_copy(trm.uuid, sd->dim_id);
 
     dictionary_set(ri->rrdmetrics, string2str(trm.id), &trm, sizeof(trm));
@@ -2481,7 +2906,7 @@ static void rrdinstance_load_chart_callback(SQL_CHART_DATA *sc, void *data) {
         .family = string_strdupz(sc->family),
         .priority = sc->priority,
         .chart_type = sc->chart_type,
-        .flags = RRD_FLAG_ARCHIVED | RRD_FLAG_DONT_PROCESS | RRD_FLAG_UPDATE_REASON_LOAD_SQL,
+        .flags = RRD_FLAG_ARCHIVED | RRD_FLAG_UPDATE_REASON_LOAD_SQL, // no need for atomics
         .rrdhost = host,
     };
 
@@ -2497,7 +2922,7 @@ static void rrdinstance_load_chart_callback(SQL_CHART_DATA *sc, void *data) {
         .chart_type = sc->chart_type,
         .priority = sc->priority,
         .update_every = sc->update_every,
-        .flags = RRD_FLAG_ARCHIVED | RRD_FLAG_DONT_PROCESS | RRD_FLAG_UPDATE_REASON_LOAD_SQL,
+        .flags = RRD_FLAG_ARCHIVED | RRD_FLAG_UPDATE_REASON_LOAD_SQL, // no need for atomics
     };
     uuid_copy(tri.uuid, sc->chart_id);
 
@@ -2506,13 +2931,7 @@ static void rrdinstance_load_chart_callback(SQL_CHART_DATA *sc, void *data) {
 
     ctx_get_dimension_list(&ri->uuid, rrdinstance_load_dimension, ri);
     ctx_get_label_list(&ri->uuid, rrdinstance_load_clabel, ri);
-    ri->flags &= ~RRD_FLAG_DONT_PROCESS;
-    rrdinstance_trigger_updates(ri, true, true);
-
-    // let the instance be in "don't process" mode
-    // so that we process it once, when it is collected
-    ri->flags |= RRD_FLAG_DONT_PROCESS;
-
+    rrdinstance_trigger_updates(ri, __FUNCTION__ );
     rrdinstance_release(ria);
     rrdcontext_release(rca);
 }
@@ -2523,7 +2942,7 @@ static void rrdcontext_load_context_callback(VERSIONED_CONTEXT_DATA *ctx_data, v
 
     RRDCONTEXT trc = {
         .id = string_strdupz(ctx_data->id),
-        .flags = RRD_FLAG_ARCHIVED | RRD_FLAG_DONT_PROCESS | RRD_FLAG_UPDATE_REASON_LOAD_SQL,
+        .flags = RRD_FLAG_ARCHIVED | RRD_FLAG_UPDATE_REASON_LOAD_SQL, // no need for atomics
 
         // no need to set more data here
         // we only need the hub data
@@ -2534,9 +2953,6 @@ static void rrdcontext_load_context_callback(VERSIONED_CONTEXT_DATA *ctx_data, v
 }
 
 void rrdhost_load_rrdcontext_data(RRDHOST *host) {
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        return;
-
     if(host->rrdctx) return;
 
     rrdhost_create_rrdcontexts(host);
@@ -2545,56 +2961,15 @@ void rrdhost_load_rrdcontext_data(RRDHOST *host) {
 
     RRDCONTEXT *rc;
     dfe_start_read((DICTIONARY *)host->rrdctx, rc) {
-        rc->flags &= ~RRD_FLAG_DONT_PROCESS;
-        rrdcontext_trigger_updates(rc, true);
+        rrdcontext_trigger_updates(rc, __FUNCTION__ );
     }
     dfe_done(rc);
-}
-
-// ----------------------------------------------------------------------------
-// the worker thread
-
-static inline usec_t rrdcontext_calculate_queued_dispatch_time_ut(RRDCONTEXT *rc, usec_t now_ut) {
-
-    if(likely(rc->queue.delay_calc_ut >= rc->queue.queued_ut))
-        return rc->queue.scheduled_dispatch_ut;
-
-    RRD_FLAGS flags = rc->queue.queued_flags;
-
-    usec_t delay = LONG_MAX;
-    int i;
-    struct rrdcontext_reason *reason;
-    for(i = 0, reason = &rrdcontext_reasons[i]; reason->name ; reason = &rrdcontext_reasons[++i]) {
-        if(unlikely(flags & reason->flag)) {
-            if(reason->delay_ut < delay)
-                delay = reason->delay_ut;
-        }
-    }
 
-    if(unlikely(delay == LONG_MAX)) {
-        internal_error(true, "RRDCONTEXT: '%s', cannot find minimum delay of flags %x", string2str(rc->id), (unsigned int)flags);
-        delay = 60 * USEC_PER_SEC;
-    }
-
-    rc->queue.delay_calc_ut = now_ut;
-    usec_t dispatch_ut = rc->queue.scheduled_dispatch_ut = rc->queue.queued_ut + delay;
-    return dispatch_ut;
+    rrdcontext_garbage_collect_single_host(host, false);
 }
 
-#define WORKER_JOB_HOSTS            1
-#define WORKER_JOB_CHECK            2
-#define WORKER_JOB_SEND             3
-#define WORKER_JOB_DEQUEUE          4
-#define WORKER_JOB_RETENTION        5
-#define WORKER_JOB_QUEUED           6
-#define WORKER_JOB_CLEANUP          7
-#define WORKER_JOB_CLEANUP_DELETE   8
-
-static usec_t rrdcontext_next_db_rotation_ut = 0;
-void rrdcontext_db_rotation(void) {
-    // called when the db rotates its database
-    rrdcontext_next_db_rotation_ut = now_realtime_usec() + FULL_RETENTION_SCAN_DELAY_AFTER_DB_ROTATION_SECS * USEC_PER_SEC;
-}
+// ----------------------------------------------------------------------------
+// version hash calculation
 
 static uint64_t rrdcontext_version_hash_with_callback(
     RRDHOST *host,
@@ -2612,7 +2987,7 @@ static uint64_t rrdcontext_version_hash_with_callback(
 
         rrdcontext_lock(rc);
 
-        if(unlikely(rc->flags & RRD_FLAG_HIDDEN)) {
+        if(unlikely(rrd_flag_check(rc, RRD_FLAG_HIDDEN))) {
             rrdcontext_unlock(rc);
             continue;
         }
@@ -2621,7 +2996,7 @@ static uint64_t rrdcontext_version_hash_with_callback(
             callback(rc, snapshot, bundle);
 
         // skip any deleted contexts
-        if(unlikely(rc->flags & RRD_FLAG_DELETED)) {
+        if(unlikely(rrd_flag_is_deleted(rc))) {
             rrdcontext_unlock(rc);
             continue;
         }
@@ -2646,52 +3021,154 @@ static uint64_t rrdcontext_version_hash_with_callback(
     return hash;
 }
 
-static void rrdcontext_recalculate_context_retention(RRDCONTEXT *rc, RRD_FLAGS reason, int job_id) {
-    RRDINSTANCE *ri;
-    dfe_start_read(rc->rrdinstances, ri) {
-        RRDMETRIC *rm;
-        dfe_start_read(ri->rrdmetrics, rm) {
-
-            if(job_id >= 0)
-                worker_is_busy(job_id);
-
-            rrd_flag_set_updated(rm, reason);
-
-            rm->flags &= ~RRD_FLAG_DONT_PROCESS;
-            rrdmetric_trigger_updates(rm, true, false);
-        }
-        dfe_done(rm);
-
-        ri->flags &= ~RRD_FLAG_DONT_PROCESS;
-        rrdinstance_trigger_updates(ri, true, false);
-        ri->flags |= RRD_FLAG_DONT_PROCESS;
-    }
-    dfe_done(ri);
+// ----------------------------------------------------------------------------
+// retention recalculation
 
-    rc->flags &= ~RRD_FLAG_DONT_PROCESS;
-    rrdcontext_trigger_updates(rc, true);
+static void rrdcontext_recalculate_context_retention(RRDCONTEXT *rc, RRD_FLAGS reason, bool worker_jobs) {
+    rrdcontext_post_process_updates(rc, true, reason, worker_jobs);
 }
 
-static void rrdcontext_recalculate_host_retention(RRDHOST *host, RRD_FLAGS reason, int job_id) {
+static void rrdcontext_recalculate_host_retention(RRDHOST *host, RRD_FLAGS reason, bool worker_jobs) {
     if(unlikely(!host || !host->rrdctx)) return;
 
     RRDCONTEXT *rc;
     dfe_start_read((DICTIONARY *)host->rrdctx, rc) {
-        rrdcontext_recalculate_context_retention(rc, reason, job_id);
+        rrdcontext_recalculate_context_retention(rc, reason, worker_jobs);
     }
     dfe_done(rc);
 }
 
-static void rrdcontext_recalculate_retention(int job_id) {
+static void rrdcontext_recalculate_retention_all_hosts(void) {
     rrdcontext_next_db_rotation_ut = 0;
     rrd_rdlock();
     RRDHOST *host;
     rrdhost_foreach_read(host) {
-        rrdcontext_recalculate_host_retention(host, RRD_FLAG_UPDATE_REASON_DB_ROTATION, job_id);
+        worker_is_busy(WORKER_JOB_RETENTION);
+        rrdcontext_recalculate_host_retention(host, RRD_FLAG_UPDATE_REASON_DB_ROTATION, true);
     }
     rrd_unlock();
 }
 
+// ----------------------------------------------------------------------------
+// garbage collector
+
+static bool rrdmetric_update_retention(RRDMETRIC *rm) {
+    time_t min_first_time_t = LONG_MAX, max_last_time_t = 0;
+
+    if(rm->rrddim) {
+        min_first_time_t = rrddim_first_entry_t(rm->rrddim);
+        max_last_time_t = rrddim_last_entry_t(rm->rrddim);
+    }
+#ifdef ENABLE_DBENGINE
+    else if (dbengine_enabled) {
+        RRDHOST *rrdhost = rm->ri->rc->rrdhost;
+        for (size_t tier = 0; tier < storage_tiers; tier++) {
+            if(!rrdhost->db[tier].instance) continue;
+
+            time_t first_time_t, last_time_t;
+            if (rrdeng_metric_retention_by_uuid(rrdhost->db[tier].instance, &rm->uuid, &first_time_t, &last_time_t) == 0) {
+                if (first_time_t < min_first_time_t)
+                    min_first_time_t = first_time_t;
+
+                if (last_time_t > max_last_time_t)
+                    max_last_time_t = last_time_t;
+            }
+        }
+    }
+    else {
+        // cannot get retention
+        return false;
+    }
+#endif
+
+    if(min_first_time_t == LONG_MAX)
+        min_first_time_t = 0;
+
+    if(min_first_time_t > max_last_time_t) {
+        internal_error(true, "RRDMETRIC: retention of '%s' is flipped", string2str(rm->id));
+        time_t tmp = min_first_time_t;
+        min_first_time_t = max_last_time_t;
+        max_last_time_t = tmp;
+    }
+
+    // check if retention changed
+
+    if (min_first_time_t != rm->first_time_t) {
+        rm->first_time_t = min_first_time_t;
+        rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
+    }
+
+    if (max_last_time_t != rm->last_time_t) {
+        rm->last_time_t = max_last_time_t;
+        rrd_flag_set_updated(rm, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
+    }
+
+    if(unlikely(!rm->first_time_t && !rm->last_time_t))
+        rrd_flag_set_deleted(rm, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
+
+    rrd_flag_set(rm, RRD_FLAG_LIVE_RETENTION);
+
+    return true;
+}
+
+static inline bool rrdmetric_should_be_deleted(RRDMETRIC *rm) {
+    if(likely(!rrd_flag_check(rm, RRD_FLAGS_REQUIRED_FOR_DELETIONS)))
+        return false;
+
+    if(likely(rrd_flag_check(rm, RRD_FLAGS_PREVENTING_DELETIONS)))
+        return false;
+
+    if(likely(rm->rrddim))
+        return false;
+
+    rrdmetric_update_retention(rm);
+    if(rm->first_time_t || rm->last_time_t)
+        return false;
+
+    return true;
+}
+
+static inline bool rrdinstance_should_be_deleted(RRDINSTANCE *ri) {
+    if(likely(!rrd_flag_check(ri, RRD_FLAGS_REQUIRED_FOR_DELETIONS)))
+        return false;
+
+    if(likely(rrd_flag_check(ri, RRD_FLAGS_PREVENTING_DELETIONS)))
+        return false;
+
+    if(likely(ri->rrdset))
+        return false;
+
+    if(unlikely(dictionary_referenced_items(ri->rrdmetrics) != 0))
+        return false;
+
+    if(unlikely(dictionary_entries(ri->rrdmetrics) != 0))
+        return false;
+
+    if(ri->first_time_t || ri->last_time_t)
+        return false;
+
+    return true;
+}
+
+static inline bool rrdcontext_should_be_deleted(RRDCONTEXT *rc) {
+    if(likely(!rrd_flag_check(rc, RRD_FLAGS_REQUIRED_FOR_DELETIONS)))
+        return false;
+
+    if(likely(rrd_flag_check(rc, RRD_FLAGS_PREVENTING_DELETIONS)))
+        return false;
+
+    if(unlikely(dictionary_referenced_items(rc->rrdinstances) != 0))
+        return false;
+
+    if(unlikely(dictionary_entries(rc->rrdinstances) != 0))
+        return false;
+
+    if(unlikely(rc->first_time_t || rc->last_time_t))
+        return false;
+
+    return true;
+}
+
 void rrdcontext_delete_from_sql_unsafe(RRDCONTEXT *rc) {
     // we need to refresh the string pointers in rc->hub
     // in case the context changed values
@@ -2705,80 +3182,715 @@ void rrdcontext_delete_from_sql_unsafe(RRDCONTEXT *rc) {
         error("RRDCONTEXT: failed to delete context '%s' version %"PRIu64" from SQL.", rc->hub.id, rc->hub.version);
 }
 
-static void rrdcontext_garbage_collect(void) {
+static void rrdcontext_garbage_collect_single_host(RRDHOST *host, bool worker_jobs) {
+
+    internal_error(true, "RRDCONTEXT: garbage collecting context structures of host '%s'", rrdhost_hostname(host));
+
+    RRDCONTEXT *rc;
+    dfe_start_reentrant((DICTIONARY *)host->rrdctx, rc) {
+        if(unlikely(netdata_exit)) break;
+
+        if(worker_jobs) worker_is_busy(WORKER_JOB_CLEANUP);
+
+        rrdcontext_lock(rc);
+
+        RRDINSTANCE *ri;
+        dfe_start_reentrant(rc->rrdinstances, ri) {
+            if(unlikely(netdata_exit)) break;
+
+            RRDMETRIC *rm;
+            dfe_start_write(ri->rrdmetrics, rm) {
+                if(rrdmetric_should_be_deleted(rm)) {
+                    if(worker_jobs) worker_is_busy(WORKER_JOB_CLEANUP_DELETE);
+                    if(!dictionary_del(ri->rrdmetrics, string2str(rm->id)))
+                        error("RRDCONTEXT: metric '%s' of instance '%s' of context '%s' of host '%s', failed to be deleted from rrdmetrics dictionary.",
+                              string2str(rm->id),
+                              string2str(ri->id),
+                              string2str(rc->id),
+                              rrdhost_hostname(host));
+                    else
+                        internal_error(
+                            true,
+                            "RRDCONTEXT: metric '%s' of instance '%s' of context '%s' of host '%s', deleted from rrdmetrics dictionary.",
+                            string2str(rm->id),
+                            string2str(ri->id),
+                            string2str(rc->id),
+                            rrdhost_hostname(host));
+                }
+            }
+            dfe_done(rm);
+
+            if(rrdinstance_should_be_deleted(ri)) {
+                if(worker_jobs) worker_is_busy(WORKER_JOB_CLEANUP_DELETE);
+                if(!dictionary_del(rc->rrdinstances, string2str(ri->id)))
+                    error("RRDCONTEXT: instance '%s' of context '%s' of host '%s', failed to be deleted from rrdmetrics dictionary.",
+                          string2str(ri->id),
+                          string2str(rc->id),
+                          rrdhost_hostname(host));
+                else
+                    internal_error(
+                        true,
+                        "RRDCONTEXT: instance '%s' of context '%s' of host '%s', deleted from rrdmetrics dictionary.",
+                        string2str(ri->id),
+                        string2str(rc->id),
+                        rrdhost_hostname(host));
+            }
+        }
+        dfe_done(ri);
+
+        if(unlikely(rrdcontext_should_be_deleted(rc))) {
+            if(worker_jobs) worker_is_busy(WORKER_JOB_CLEANUP_DELETE);
+            rrdcontext_dequeue_from_post_processing(rc);
+            rrdcontext_delete_from_sql_unsafe(rc);
+
+            if(!dictionary_del((DICTIONARY *)host->rrdctx, string2str(rc->id)))
+                error("RRDCONTEXT: context '%s' of host '%s', failed to be deleted from rrdmetrics dictionary.",
+                      string2str(rc->id),
+                      rrdhost_hostname(host));
+            else
+                internal_error(
+                    true,
+                    "RRDCONTEXT: context '%s' of host '%s', deleted from rrdmetrics dictionary.",
+                    string2str(rc->id),
+                    rrdhost_hostname(host));
+
+            fprintf(stderr, "RRDCONTEXT: deleted context '%s'", string2str(rc->id));
+        }
+
+        // the item is referenced in the dictionary
+        // so, it is still here to unlock, even if we have deleted it
+        rrdcontext_unlock(rc);
+    }
+    dfe_done(rc);
+}
+
+static void rrdcontext_garbage_collect_for_all_hosts(void) {
     rrd_rdlock();
     RRDHOST *host;
     rrdhost_foreach_read(host) {
-        RRDCONTEXT *rc;
-        dfe_start_write((DICTIONARY *)host->rrdctx, rc) {
-            worker_is_busy(WORKER_JOB_CLEANUP);
+        rrdcontext_garbage_collect_single_host(host, true);
+    }
+    rrd_unlock();
+}
+
+// ----------------------------------------------------------------------------
+// post processing
+
+static void rrdmetric_process_updates(RRDMETRIC *rm, bool force, RRD_FLAGS reason, bool worker_jobs) {
+    if(reason != RRD_FLAG_NONE)
+        rrd_flag_set_updated(rm, reason);
+
+    if(!force && !rrd_flag_is_updated(rm) && rrd_flag_check(rm, RRD_FLAG_LIVE_RETENTION) && !rrd_flag_check(rm, RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION))
+        return;
+
+    if(worker_jobs)
+        worker_is_busy(WORKER_JOB_PP_METRIC);
+
+    if(reason & RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD) {
+        rrd_flag_set_archived(rm);
+        rrd_flag_set(rm, RRD_FLAG_UPDATE_REASON_DISCONNECTED_CHILD);
+    }
+    if(rrd_flag_is_deleted(rm) && (reason & RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION))
+        rrd_flag_set_archived(rm);
+
+    rrdmetric_update_retention(rm);
+
+    rrd_flag_unset_updated(rm);
+}
+
+static void rrdinstance_post_process_updates(RRDINSTANCE *ri, bool force, RRD_FLAGS reason, bool worker_jobs) {
+    if(reason != RRD_FLAG_NONE)
+        rrd_flag_set_updated(ri, reason);
+
+    if(!force && !rrd_flag_is_updated(ri) && rrd_flag_check(ri, RRD_FLAG_LIVE_RETENTION))
+        return;
+
+    if(worker_jobs)
+        worker_is_busy(WORKER_JOB_PP_INSTANCE);
+
+    time_t min_first_time_t = LONG_MAX, max_last_time_t = 0;
+    size_t metrics_active = 0, metrics_deleted = 0;
+    bool live_retention = true, currently_collected = false;
+    if(dictionary_entries(ri->rrdmetrics) > 0) {
+        RRDMETRIC *rm;
+        dfe_start_read((DICTIONARY *)ri->rrdmetrics, rm) {
+            if(unlikely(netdata_exit)) break;
+
+            RRD_FLAGS reason_to_pass = reason;
+            if(rrd_flag_check(ri, RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION))
+                reason_to_pass |= RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION;
+
+            rrdmetric_process_updates(rm, force, reason_to_pass, worker_jobs);
+
+            if(unlikely(!rrd_flag_check(rm, RRD_FLAG_LIVE_RETENTION)))
+                live_retention = false;
+
+            if (unlikely((rrdmetric_should_be_deleted(rm)))) {
+                metrics_deleted++;
+                continue;
+            }
+
+            if(!currently_collected && rrd_flag_check(rm, RRD_FLAG_COLLECTED) && rm->first_time_t)
+                currently_collected = true;
+
+            metrics_active++;
+
+            if (rm->first_time_t && rm->first_time_t < min_first_time_t)
+                min_first_time_t = rm->first_time_t;
+
+            if (rm->last_time_t && rm->last_time_t > max_last_time_t)
+                max_last_time_t = rm->last_time_t;
+        }
+        dfe_done(rm);
+    }
+
+    if(unlikely(live_retention && !rrd_flag_check(ri, RRD_FLAG_LIVE_RETENTION)))
+        rrd_flag_set(ri, RRD_FLAG_LIVE_RETENTION);
+    else if(unlikely(!live_retention && rrd_flag_check(ri, RRD_FLAG_LIVE_RETENTION)))
+        rrd_flag_clear(ri, RRD_FLAG_LIVE_RETENTION);
+
+    if(unlikely(!metrics_active)) {
+        // no metrics available
+
+        if(ri->first_time_t) {
+            ri->first_time_t = 0;
+            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
+        }
+
+        if(ri->last_time_t) {
+            ri->last_time_t = 0;
+            rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
+        }
+
+        rrd_flag_set_deleted(ri, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
+    }
+    else {
+        // we have active metrics...
+
+        if (unlikely(min_first_time_t == LONG_MAX))
+            min_first_time_t = 0;
+
+        if (unlikely(min_first_time_t == 0 || max_last_time_t == 0)) {
+            if(ri->first_time_t) {
+                ri->first_time_t = 0;
+                rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
+            }
+
+            if(ri->last_time_t) {
+                ri->last_time_t = 0;
+                rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
+            }
+
+            if(likely(live_retention))
+                rrd_flag_set_deleted(ri, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
+        }
+        else {
+            rrd_flag_clear(ri, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
+
+            if (unlikely(ri->first_time_t != min_first_time_t)) {
+                ri->first_time_t = min_first_time_t;
+                rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
+            }
+
+            if (unlikely(ri->last_time_t != max_last_time_t)) {
+                ri->last_time_t = max_last_time_t;
+                rrd_flag_set_updated(ri, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
+            }
+
+            if(likely(currently_collected))
+                rrd_flag_set_collected(ri);
+            else
+                rrd_flag_set_archived(ri);
+        }
+    }
+
+    rrd_flag_unset_updated(ri);
+}
+
+static void rrdcontext_post_process_updates(RRDCONTEXT *rc, bool force, RRD_FLAGS reason, bool worker_jobs) {
+    if(reason != RRD_FLAG_NONE)
+        rrd_flag_set_updated(rc, reason);
+
+    if(worker_jobs)
+        worker_is_busy(WORKER_JOB_PP_CONTEXT);
+
+    size_t min_priority = LONG_MAX;
+    time_t min_first_time_t = LONG_MAX, max_last_time_t = 0;
+    size_t instances_active = 0, instances_deleted = 0;
+    bool live_retention = true, currently_collected = false, hidden = true;
+    if(dictionary_entries(rc->rrdinstances) > 0) {
+        RRDINSTANCE *ri;
+        dfe_start_reentrant(rc->rrdinstances, ri) {
+            if(unlikely(netdata_exit)) break;
+
+            RRD_FLAGS reason_to_pass = reason;
+            if(rrd_flag_check(rc, RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION))
+                reason_to_pass |= RRD_FLAG_UPDATE_REASON_UPDATE_RETENTION;
+
+            rrdinstance_post_process_updates(ri, force, reason_to_pass, worker_jobs);
+
+            if(unlikely(hidden && !rrd_flag_check(ri, RRD_FLAG_HIDDEN)))
+                hidden = false;
+
+            if(unlikely(live_retention && !rrd_flag_check(ri, RRD_FLAG_LIVE_RETENTION)))
+                live_retention = false;
+
+            if (unlikely(rrdinstance_should_be_deleted(ri))) {
+                instances_deleted++;
+                continue;
+            }
+
+            if(unlikely(!currently_collected && rrd_flag_is_collected(ri) && ri->first_time_t))
+                currently_collected = true;
+
+            internal_error(rc->units != ri->units,
+                           "RRDCONTEXT: '%s' rrdinstance '%s' has different units, context '%s', instance '%s'",
+                           string2str(rc->id), string2str(ri->id),
+                           string2str(rc->units), string2str(ri->units));
+
+            instances_active++;
+
+            if (ri->priority >= RRDCONTEXT_MINIMUM_ALLOWED_PRIORITY && ri->priority < min_priority)
+                min_priority = ri->priority;
+
+            if (ri->first_time_t && ri->first_time_t < min_first_time_t)
+                min_first_time_t = ri->first_time_t;
+
+            if (ri->last_time_t && ri->last_time_t > max_last_time_t)
+                max_last_time_t = ri->last_time_t;
+        }
+        dfe_done(ri);
+    }
+
+    {
+        bool previous_hidden = rrd_flag_check(rc, RRD_FLAG_HIDDEN);
+        if (hidden != previous_hidden) {
+            if (hidden && !rrd_flag_check(rc, RRD_FLAG_HIDDEN))
+                rrd_flag_set(rc, RRD_FLAG_HIDDEN);
+            else if (!hidden && rrd_flag_check(rc, RRD_FLAG_HIDDEN))
+                rrd_flag_clear(rc, RRD_FLAG_HIDDEN);
+        }
+
+        bool previous_live_retention = rrd_flag_check(rc, RRD_FLAG_LIVE_RETENTION);
+        if (live_retention != previous_live_retention) {
+            if (live_retention && !rrd_flag_check(rc, RRD_FLAG_LIVE_RETENTION))
+                rrd_flag_set(rc, RRD_FLAG_LIVE_RETENTION);
+            else if (!live_retention && rrd_flag_check(rc, RRD_FLAG_LIVE_RETENTION))
+                rrd_flag_clear(rc, RRD_FLAG_LIVE_RETENTION);
+        }
+    }
+
+    rrdcontext_lock(rc);
+    rc->pp.executions++;
+
+    if(unlikely(!instances_active)) {
+        // we had some instances, but they are gone now...
+
+        if(rc->first_time_t) {
+            rc->first_time_t = 0;
+            rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
+        }
+
+        if(rc->last_time_t) {
+            rc->last_time_t = 0;
+            rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
+        }
+
+        rrd_flag_set_deleted(rc, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
+    }
+    else {
+        // we have some active instances...
+
+        if (unlikely(min_first_time_t == LONG_MAX))
+            min_first_time_t = 0;
+
+        if (unlikely(min_first_time_t == 0 && max_last_time_t == 0)) {
+            if(rc->first_time_t) {
+                rc->first_time_t = 0;
+                rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
+            }
+
+            if(rc->last_time_t) {
+                rc->last_time_t = 0;
+                rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
+            }
+
+            rrd_flag_set_deleted(rc, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
+        }
+        else {
+            rrd_flag_clear(rc, RRD_FLAG_UPDATE_REASON_ZERO_RETENTION);
+
+            if (unlikely(rc->first_time_t != min_first_time_t)) {
+                rc->first_time_t = min_first_time_t;
+                rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_FIRST_TIME_T);
+            }
+
+            if (rc->last_time_t != max_last_time_t) {
+                rc->last_time_t = max_last_time_t;
+                rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_LAST_TIME_T);
+            }
+
+            if(likely(currently_collected))
+                rrd_flag_set_collected(rc);
+            else
+                rrd_flag_set_archived(rc);
+        }
+
+        if (min_priority != LONG_MAX && rc->priority != min_priority) {
+            rc->priority = min_priority;
+            rrd_flag_set_updated(rc, RRD_FLAG_UPDATE_REASON_CHANGED_METADATA);
+        }
+    }
+
+    if(unlikely(rrd_flag_is_updated(rc) && rc->rrdhost->rrdctx_hub_queue)) {
+        if(check_if_cloud_version_changed_unsafe(rc, false)) {
+            rc->version = rrdcontext_get_next_version(rc);
+            dictionary_set((DICTIONARY *)rc->rrdhost->rrdctx_hub_queue,
+                           string2str(rc->id), rc, sizeof(*rc));
+        }
+    }
+
+    rrd_flag_unset_updated(rc);
+    rrdcontext_unlock(rc);
+}
+
+static void rrdcontext_queue_for_post_processing(RRDCONTEXT *rc, const char *function __maybe_unused, RRD_FLAGS flags __maybe_unused) {
+    if(unlikely(!rc->rrdhost->rrdctx_post_processing_queue)) return;
+
+    if(!rrd_flag_check(rc, RRD_FLAG_QUEUED_FOR_PP)) {
+        dictionary_set((DICTIONARY *)rc->rrdhost->rrdctx_post_processing_queue,
+                       string2str(rc->id),
+                       rc,
+                       sizeof(*rc));
+
+#if(defined(NETDATA_INTERNAL_CHECKS) && defined(LOG_POST_PROCESSING_QUEUE_INSERTIONS))
+        {
+            BUFFER *wb_flags = buffer_create(1000);
+            rrd_flags_to_buffer(flags, wb_flags);
+
+            BUFFER *wb_reasons = buffer_create(1000);
+            rrd_reasons_to_buffer(flags, wb_reasons);
+
+            internal_error(true, "RRDCONTEXT: '%s' update triggered by function %s(), due to flags: %s, reasons: %s",
+                           string2str(rc->id), function,
+                           buffer_tostring(wb_flags),
+                           buffer_tostring(wb_reasons));
+
+            buffer_free(wb_reasons);
+            buffer_free(wb_flags);
+        }
+#endif
+    }
+}
+
+static void rrdcontext_dequeue_from_post_processing(RRDCONTEXT *rc) {
+    if(unlikely(!rc->rrdhost->rrdctx_post_processing_queue)) return;
+    dictionary_del((DICTIONARY *)rc->rrdhost->rrdctx_post_processing_queue, string2str(rc->id));
+}
+
+static void rrdcontext_post_process_queued_contexts(RRDHOST *host) {
+    if(unlikely(!host->rrdctx_post_processing_queue)) return;
+
+    RRDCONTEXT *rc;
+    dfe_start_reentrant((DICTIONARY *)host->rrdctx_post_processing_queue, rc) {
+        if(unlikely(netdata_exit)) break;
+
+        rrdcontext_dequeue_from_post_processing(rc);
+        rrdcontext_post_process_updates(rc, false, RRD_FLAG_NONE, true);
+    }
+    dfe_done(rc);
+}
+
+// ----------------------------------------------------------------------------
+// dispatching contexts to cloud
+
+static uint64_t rrdcontext_get_next_version(RRDCONTEXT *rc) {
+    time_t now = now_realtime_sec();
+    uint64_t version = MAX(rc->version, rc->hub.version);
+    version = MAX((uint64_t)now, version);
+    version++;
+    return version;
+}
+
+static void rrdcontext_message_send_unsafe(RRDCONTEXT *rc, bool snapshot __maybe_unused, void *bundle __maybe_unused) {
+
+    // save it, so that we know the last version we sent to hub
+    rc->version = rc->hub.version = rrdcontext_get_next_version(rc);
+    rc->hub.id = string2str(rc->id);
+    rc->hub.title = string2str(rc->title);
+    rc->hub.units = string2str(rc->units);
+    rc->hub.family = string2str(rc->family);
+    rc->hub.chart_type = rrdset_type_name(rc->chart_type);
+    rc->hub.priority = rc->priority;
+    rc->hub.first_time_t = rc->first_time_t;
+    rc->hub.last_time_t = rrd_flag_is_collected(rc) ? 0 : rc->last_time_t;
+    rc->hub.deleted = rrd_flag_is_deleted(rc) ? true : false;
+
+#ifdef ENABLE_ACLK
+    struct context_updated message = {
+        .id = rc->hub.id,
+        .version = rc->hub.version,
+        .title = rc->hub.title,
+        .units = rc->hub.units,
+        .family = rc->hub.family,
+        .chart_type = rc->hub.chart_type,
+        .priority = rc->hub.priority,
+        .first_entry = rc->hub.first_time_t,
+        .last_entry = rc->hub.last_time_t,
+        .deleted = rc->hub.deleted,
+    };
+
+    if(likely(!rrd_flag_check(rc, RRD_FLAG_HIDDEN))) {
+        if (snapshot) {
+            if (!rc->hub.deleted)
+                contexts_snapshot_add_ctx_update(bundle, &message);
+        }
+        else
+            contexts_updated_add_ctx_update(bundle, &message);
+    }
+#endif
+
+    // store it to SQL
+
+    if(rrd_flag_is_deleted(rc))
+        rrdcontext_delete_from_sql_unsafe(rc);
+
+    else if (ctx_store_context(&rc->rrdhost->host_uuid, &rc->hub) != 0)
+        error("RRDCONTEXT: failed to save context '%s' version %"PRIu64" to SQL.", rc->hub.id, rc->hub.version);
+}
+
+static bool check_if_cloud_version_changed_unsafe(RRDCONTEXT *rc, bool sending __maybe_unused) {
+    bool id_changed = false,
+         title_changed = false,
+         units_changed = false,
+         family_changed = false,
+         chart_type_changed = false,
+         priority_changed = false,
+         first_time_changed = false,
+         last_time_changed = false,
+         deleted_changed = false;
+
+    RRD_FLAGS flags = rrd_flags_get(rc);
+
+    if(unlikely(string2str(rc->id) != rc->hub.id))
+        id_changed = true;
+
+    if(unlikely(string2str(rc->title) != rc->hub.title))
+        title_changed = true;
+
+    if(unlikely(string2str(rc->units) != rc->hub.units))
+        units_changed = true;
+
+    if(unlikely(string2str(rc->family) != rc->hub.family))
+        family_changed = true;
+
+    if(unlikely(rrdset_type_name(rc->chart_type) != rc->hub.chart_type))
+        chart_type_changed = true;
+
+    if(unlikely(rc->priority != rc->hub.priority))
+        priority_changed = true;
+
+    if(unlikely((uint64_t)rc->first_time_t != rc->hub.first_time_t))
+        first_time_changed = true;
+
+    if(unlikely((uint64_t)((flags & RRD_FLAG_COLLECTED) ? 0 : rc->last_time_t) != rc->hub.last_time_t))
+        last_time_changed = true;
+
+    if(unlikely(((flags & RRD_FLAG_DELETED) ? true : false) != rc->hub.deleted))
+        deleted_changed = true;
+
+    if(unlikely(id_changed || title_changed || units_changed || family_changed || chart_type_changed || priority_changed || first_time_changed || last_time_changed || deleted_changed)) {
+
+        internal_error(LOG_TRANSITIONS,
+                       "RRDCONTEXT: %s NEW VERSION '%s'%s of host '%s', version %"PRIu64", title '%s'%s, units '%s'%s, family '%s'%s, chart type '%s'%s, priority %u%s, first_time_t %ld%s, last_time_t %ld%s, deleted '%s'%s, (queued for %llu ms, expected %llu ms)",
+                       sending?"SENDING":"QUEUE",
+                       string2str(rc->id), id_changed ? " (CHANGED)" : "",
+                       rrdhost_hostname(rc->rrdhost),
+                       rc->version,
+                       string2str(rc->title), title_changed ? " (CHANGED)" : "",
+                       string2str(rc->units), units_changed ? " (CHANGED)" : "",
+                       string2str(rc->family), family_changed ? " (CHANGED)" : "",
+                       rrdset_type_name(rc->chart_type), chart_type_changed ? " (CHANGED)" : "",
+                       rc->priority, priority_changed ? " (CHANGED)" : "",
+                       rc->first_time_t, first_time_changed ? " (CHANGED)" : "",
+                       (flags & RRD_FLAG_COLLECTED) ? 0 : rc->last_time_t, last_time_changed ? " (CHANGED)" : "",
+                       (flags & RRD_FLAG_DELETED) ? "true" : "false", deleted_changed ? " (CHANGED)" : "",
+                       sending ? (now_realtime_usec() - rc->queue.queued_ut) / USEC_PER_MS : 0,
+                       sending ? (rc->queue.scheduled_dispatch_ut - rc->queue.queued_ut) / USEC_PER_MS : 0
+        );
+
+        return true;
+    }
+
+    return false;
+}
+
+static inline usec_t rrdcontext_calculate_queued_dispatch_time_ut(RRDCONTEXT *rc, usec_t now_ut) {
+
+    if(likely(rc->queue.delay_calc_ut >= rc->queue.queued_ut))
+        return rc->queue.scheduled_dispatch_ut;
+
+    RRD_FLAGS flags = rc->queue.queued_flags;
+
+    usec_t delay = LONG_MAX;
+    int i;
+    struct rrdcontext_reason *reason;
+    for(i = 0, reason = &rrdcontext_reasons[i]; reason->name ; reason = &rrdcontext_reasons[++i]) {
+        if(unlikely(flags & reason->flag)) {
+            if(reason->delay_ut < delay)
+                delay = reason->delay_ut;
+        }
+    }
+
+    if(unlikely(delay == LONG_MAX)) {
+        internal_error(true, "RRDCONTEXT: '%s', cannot find minimum delay of flags %x", string2str(rc->id), (unsigned int)flags);
+        delay = 60 * USEC_PER_SEC;
+    }
+
+    rc->queue.delay_calc_ut = now_ut;
+    usec_t dispatch_ut = rc->queue.scheduled_dispatch_ut = rc->queue.queued_ut + delay;
+    return dispatch_ut;
+}
+
+static void rrdcontext_dequeue_from_hub_queue(RRDCONTEXT *rc) {
+    dictionary_del((DICTIONARY *)rc->rrdhost->rrdctx_hub_queue, string2str(rc->id));
+}
+
+static void rrdcontext_dispatch_queued_contexts_to_hub(RRDHOST *host, usec_t now_ut) {
+
+    // check if we have received a streaming command for this host
+    if(!rrdhost_flag_check(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS) || !aclk_connected || !host->rrdctx_hub_queue)
+        return;
+
+    // check if there are queued items to send
+    if(!dictionary_entries((DICTIONARY *)host->rrdctx_hub_queue))
+        return;
+
+    if(!host->node_id)
+        return;
+
+    size_t messages_added = 0;
+    contexts_updated_t bundle = NULL;
+
+    RRDCONTEXT *rc;
+    dfe_start_reentrant((DICTIONARY *)host->rrdctx_hub_queue, rc) {
+        if(unlikely(netdata_exit)) break;
+
+        if(unlikely(messages_added >= MESSAGES_PER_BUNDLE_TO_SEND_TO_HUB_PER_HOST))
+            break;
+
+        worker_is_busy(WORKER_JOB_QUEUED);
+        usec_t dispatch_ut = rrdcontext_calculate_queued_dispatch_time_ut(rc, now_ut);
+        char *claim_id = get_agent_claimid();
+
+        if(unlikely(now_ut >= dispatch_ut) && claim_id) {
+            worker_is_busy(WORKER_JOB_CHECK);
 
             rrdcontext_lock(rc);
 
+            if(check_if_cloud_version_changed_unsafe(rc, true)) {
+                worker_is_busy(WORKER_JOB_SEND);
+
+#ifdef ENABLE_ACLK
+                if(!bundle) {
+                    // prepare the bundle to send the messages
+                    char uuid[UUID_STR_LEN];
+                    uuid_unparse_lower(*host->node_id, uuid);
+
+                    bundle = contexts_updated_new(claim_id, uuid, 0, now_ut);
+                }
+#endif
+                // update the hub data of the context, give a new version, pack the message
+                // and save an update to SQL
+                rrdcontext_message_send_unsafe(rc, false, bundle);
+                messages_added++;
+
+                rc->queue.dispatches++;
+                rc->queue.dequeued_ut = now_ut;
+            }
+            else
+                rc->version = rc->hub.version;
+
+            // remove it from the queue
+            worker_is_busy(WORKER_JOB_DEQUEUE);
+            rrdcontext_dequeue_from_hub_queue(rc);
+
             if(unlikely(rrdcontext_should_be_deleted(rc))) {
+                // this is a deleted context - delete it forever...
+
                 worker_is_busy(WORKER_JOB_CLEANUP_DELETE);
+
+                rrdcontext_dequeue_from_post_processing(rc);
                 rrdcontext_delete_from_sql_unsafe(rc);
 
-                if(dictionary_del_having_write_lock((DICTIONARY *)host->rrdctx, string2str(rc->id)) != 0)
+                STRING *id = string_dup(rc->id);
+                rrdcontext_unlock(rc);
+
+                // delete it from the master dictionary
+                if(!dictionary_del((DICTIONARY *)host->rrdctx, string2str(rc->id)))
                     error("RRDCONTEXT: '%s' of host '%s' failed to be deleted from rrdcontext dictionary.",
-                          string2str(rc->id), host->hostname);
-            }
-            else {
-                RRDINSTANCE *ri;
-                dfe_start_write(rc->rrdinstances, ri) {
-                    if(rrdinstance_should_be_deleted(ri)) {
-                        worker_is_busy(WORKER_JOB_CLEANUP_DELETE);
-                        dictionary_del_having_write_lock(rc->rrdinstances, string2str(ri->id));
-                    }
-                    else {
-                        RRDMETRIC *rm;
-                        dfe_start_write(ri->rrdmetrics, rm) {
-                            if(rrdmetric_should_be_deleted(rm)) {
-                                worker_is_busy(WORKER_JOB_CLEANUP_DELETE);
-                                dictionary_del_having_write_lock(ri->rrdmetrics, string2str(rm->id));
-                            }
-                        }
-                        dfe_done(rm);
-                    }
-                }
-                dfe_done(ri);
-            }
+                          string2str(id), rrdhost_hostname(host));
 
-            // the item is referenced in the dictionary
-            // so, it is still here to unlock, even if we have deleted it
-            rrdcontext_unlock(rc);
+                string_freez(id);
+            }
+            else
+                rrdcontext_unlock(rc);
         }
-        dfe_done(rc);
+        freez(claim_id);
     }
-    rrd_unlock();
+    dfe_done(rc);
+
+#ifdef ENABLE_ACLK
+    if(!netdata_exit && bundle) {
+        // we have a bundle to send messages
+
+        // update the version hash
+        contexts_updated_update_version_hash(bundle, rrdcontext_version_hash(host));
+
+        // send it
+        aclk_send_contexts_updated(bundle);
+    }
+    else if(bundle)
+        contexts_updated_delete(bundle);
+#endif
+
 }
 
+// ----------------------------------------------------------------------------
+// worker thread
+
 static void rrdcontext_main_cleanup(void *ptr) {
     struct netdata_static_thread *static_thread = (struct netdata_static_thread *)ptr;
     static_thread->enabled = NETDATA_MAIN_THREAD_EXITING;
+
     // custom code
+    worker_unregister();
+
     static_thread->enabled = NETDATA_MAIN_THREAD_EXITED;
 }
 
 void *rrdcontext_main(void *ptr) {
     netdata_thread_cleanup_push(rrdcontext_main_cleanup, ptr);
 
-    if(unlikely(rrdcontext_enabled == CONFIG_BOOLEAN_NO))
-        goto exit;
-
     worker_register("RRDCONTEXT");
     worker_register_job_name(WORKER_JOB_HOSTS, "hosts");
     worker_register_job_name(WORKER_JOB_CHECK, "dedup checks");
     worker_register_job_name(WORKER_JOB_SEND, "sent contexts");
-    worker_register_job_name(WORKER_JOB_DEQUEUE, "deduped contexts");
+    worker_register_job_name(WORKER_JOB_DEQUEUE, "deduplicated contexts");
     worker_register_job_name(WORKER_JOB_RETENTION, "metrics retention");
     worker_register_job_name(WORKER_JOB_QUEUED, "queued contexts");
     worker_register_job_name(WORKER_JOB_CLEANUP, "cleanups");
     worker_register_job_name(WORKER_JOB_CLEANUP_DELETE, "deletes");
+    worker_register_job_name(WORKER_JOB_PP_METRIC, "check metrics");
+    worker_register_job_name(WORKER_JOB_PP_INSTANCE, "check instances");
+    worker_register_job_name(WORKER_JOB_PP_CONTEXT, "check contexts");
+
+    worker_register_job_custom_metric(WORKER_JOB_HUB_QUEUE_SIZE, "hub queue size", "contexts", WORKER_METRIC_ABSOLUTE);
+    worker_register_job_custom_metric(WORKER_JOB_PP_QUEUE_SIZE, "post processing queue size", "contexts", WORKER_METRIC_ABSOLUTE);
 
     heartbeat_t hb;
     heartbeat_init(&hb);
-    usec_t step = USEC_PER_SEC * RRDCONTEXT_WORKER_THREAD_HEARTBEAT_SECS;
+    usec_t step = RRDCONTEXT_WORKER_THREAD_HEARTBEAT_USEC;
 
     while (!netdata_exit) {
         worker_is_idle();
@@ -2786,16 +3898,17 @@ void *rrdcontext_main(void *ptr) {
 
         if(unlikely(netdata_exit)) break;
 
-        if(!aclk_connected) continue;
-
         usec_t now_ut = now_realtime_usec();
 
         if(rrdcontext_next_db_rotation_ut && now_ut > rrdcontext_next_db_rotation_ut) {
-            rrdcontext_recalculate_retention(WORKER_JOB_RETENTION);
-            rrdcontext_garbage_collect();
+            rrdcontext_recalculate_retention_all_hosts();
+            rrdcontext_garbage_collect_for_all_hosts();
             rrdcontext_next_db_rotation_ut = 0;
         }
 
+        size_t hub_queued_contexts_for_all_hosts = 0;
+        size_t pp_queued_contexts_for_all_hosts = 0;
+
         rrd_rdlock();
         RRDHOST *host;
         rrdhost_foreach_read(host) {
@@ -2803,106 +3916,23 @@ void *rrdcontext_main(void *ptr) {
 
             worker_is_busy(WORKER_JOB_HOSTS);
 
-            // check if we have received a streaming command for this host
-            if(!rrdhost_flag_check(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS))
-                continue;
-
-            // check if there are queued items to send
-            if(!dictionary_stats_entries((DICTIONARY *)host->rrdctx_queue))
-                continue;
-
-            if(!host->node_id)
-                continue;
-
-            size_t messages_added = 0;
-            contexts_updated_t bundle = NULL;
-
-            RRDCONTEXT *rc;
-            dfe_start_write((DICTIONARY *)host->rrdctx_queue, rc) {
-                if(unlikely(netdata_exit)) break;
-
-                if(unlikely(messages_added >= MESSAGES_PER_BUNDLE_TO_SEND_TO_HUB_PER_HOST))
-                    break;
-
-                worker_is_busy(WORKER_JOB_QUEUED);
-                usec_t dispatch_ut = rrdcontext_calculate_queued_dispatch_time_ut(rc, now_ut);
-                char *claim_id = get_agent_claimid();
-                if(unlikely(now_ut >= dispatch_ut) && claim_id) {
-                    worker_is_busy(WORKER_JOB_CHECK);
-
-                    rrdcontext_lock(rc);
-
-                    if(check_if_cloud_version_changed_unsafe(rc, true)) {
-                        worker_is_busy(WORKER_JOB_SEND);
-
-#ifdef ENABLE_ACLK
-                        if(!bundle) {
-                            // prepare the bundle to send the messages
-                            char uuid[UUID_STR_LEN];
-                            uuid_unparse_lower(*host->node_id, uuid);
-
-                            bundle = contexts_updated_new(claim_id, uuid, 0, now_ut);
-                        }
-#endif
-                        // update the hub data of the context, give a new version, pack the message
-                        // and save an update to SQL
-                        rrdcontext_message_send_unsafe(rc, false, bundle);
-                        messages_added++;
-
-                        rc->queue.dequeued_ut = now_ut;
-                    }
-                    else
-                        rc->version = rc->hub.version;
-                    
-                    // remove the queued flag, so that it can be queued again
-                    rc->flags &= ~RRD_FLAG_QUEUED;
-
-                    // remove it from the queue
-                    worker_is_busy(WORKER_JOB_DEQUEUE);
-                    dictionary_del_having_write_lock((DICTIONARY *)host->rrdctx_queue, string2str(rc->id));
-
-                    if(unlikely(rrdcontext_should_be_deleted(rc))) {
-                        // this is a deleted context - delete it forever...
-
-                        worker_is_busy(WORKER_JOB_CLEANUP_DELETE);
-                        rrdcontext_delete_from_sql_unsafe(rc);
-
-                        STRING *id = string_dup(rc->id);
-                        rrdcontext_unlock(rc);
-
-                        // delete it from the master dictionary
-                        if(dictionary_del((DICTIONARY *)host->rrdctx, string2str(rc->id)) != 0)
-                            error("RRDCONTEXT: '%s' of host '%s' failed to be deleted from rrdcontext dictionary.",
-                                  string2str(id), host->hostname);
-
-                        string_freez(id);
-                    }
-                    else
-                        rrdcontext_unlock(rc);
-                }
-                freez(claim_id);
+            if(host->rrdctx_post_processing_queue) {
+                pp_queued_contexts_for_all_hosts +=
+                    dictionary_entries((DICTIONARY *)host->rrdctx_post_processing_queue);
+                rrdcontext_post_process_queued_contexts(host);
             }
-            dfe_done(rc);
-
-#ifdef ENABLE_ACLK
-            if(!netdata_exit && bundle) {
-                // we have a bundle to send messages
 
-                // update the version hash
-                contexts_updated_update_version_hash(bundle, rrdcontext_version_hash(host));
-
-                // send it
-                aclk_send_contexts_updated(bundle);
+            if(host->rrdctx_hub_queue) {
+                hub_queued_contexts_for_all_hosts += dictionary_entries((DICTIONARY *)host->rrdctx_hub_queue);
+                rrdcontext_dispatch_queued_contexts_to_hub(host, now_ut);
             }
-            else if(bundle)
-                contexts_updated_delete(bundle);
-#endif
         }
         rrd_unlock();
 
+        worker_set_metric(WORKER_JOB_HUB_QUEUE_SIZE, (NETDATA_DOUBLE)hub_queued_contexts_for_all_hosts);
+        worker_set_metric(WORKER_JOB_PP_QUEUE_SIZE, (NETDATA_DOUBLE)pp_queued_contexts_for_all_hosts);
     }
 
-exit:
     netdata_thread_cleanup_pop(1);
     return NULL;
 }
diff --git a/database/rrdcontext.h b/database/rrdcontext.h
index a9e0bd2e3..67e6cf394 100644
--- a/database/rrdcontext.h
+++ b/database/rrdcontext.h
@@ -8,7 +8,6 @@
 
 typedef struct rrdmetric_acquired RRDMETRIC_ACQUIRED;
 
-
 // ----------------------------------------------------------------------------
 // RRDINSTANCE
 
@@ -24,15 +23,26 @@ typedef struct rrdcontext_acquired RRDCONTEXT_ACQUIRED;
 
 #include "rrd.h"
 
+const char *rrdmetric_acquired_id(RRDMETRIC_ACQUIRED *rma);
+const char *rrdmetric_acquired_name(RRDMETRIC_ACQUIRED *rma);
+NETDATA_DOUBLE rrdmetric_acquired_last_stored_value(RRDMETRIC_ACQUIRED *rma);
+
+const char *rrdinstance_acquired_id(RRDINSTANCE_ACQUIRED *ria);
+const char *rrdinstance_acquired_name(RRDINSTANCE_ACQUIRED *ria);
+DICTIONARY *rrdinstance_acquired_labels(RRDINSTANCE_ACQUIRED *ria);
+DICTIONARY *rrdinstance_acquired_functions(RRDINSTANCE_ACQUIRED *ria);
+
 // ----------------------------------------------------------------------------
 // public API for rrdhost
 
-extern void rrdhost_load_rrdcontext_data(RRDHOST *host);
-extern void rrdhost_create_rrdcontexts(RRDHOST *host);
-extern void rrdhost_destroy_rrdcontexts(RRDHOST *host);
+void rrdhost_load_rrdcontext_data(RRDHOST *host);
+void rrdhost_create_rrdcontexts(RRDHOST *host);
+void rrdhost_destroy_rrdcontexts(RRDHOST *host);
 
-extern void rrdcontext_host_child_connected(RRDHOST *host);
-extern void rrdcontext_host_child_disconnected(RRDHOST *host);
+void rrdcontext_host_child_connected(RRDHOST *host);
+void rrdcontext_host_child_disconnected(RRDHOST *host);
+
+int rrdcontext_foreach_instance_with_rrdset_in_context(RRDHOST *host, const char *context, int (*callback)(RRDSET *st, void *data), void *data);
 
 typedef enum {
     RRDCONTEXT_OPTION_NONE               = 0,
@@ -50,43 +60,191 @@ typedef enum {
 
 #define RRDCONTEXT_OPTIONS_ALL (RRDCONTEXT_OPTION_SHOW_METRICS|RRDCONTEXT_OPTION_SHOW_INSTANCES|RRDCONTEXT_OPTION_SHOW_LABELS|RRDCONTEXT_OPTION_SHOW_QUEUED|RRDCONTEXT_OPTION_SHOW_FLAGS|RRDCONTEXT_OPTION_SHOW_DELETED|RRDCONTEXT_OPTION_SHOW_UUIDS|RRDCONTEXT_OPTION_SHOW_HIDDEN)
 
-extern int rrdcontext_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before, RRDCONTEXT_TO_JSON_OPTIONS options, const char *context, SIMPLE_PATTERN *chart_label_key, SIMPLE_PATTERN *chart_labels_filter, SIMPLE_PATTERN *chart_dimensions);
-extern int rrdcontexts_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before, RRDCONTEXT_TO_JSON_OPTIONS options, SIMPLE_PATTERN *chart_label_key, SIMPLE_PATTERN *chart_labels_filter, SIMPLE_PATTERN *chart_dimensions);
+int rrdcontext_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before, RRDCONTEXT_TO_JSON_OPTIONS options, const char *context, SIMPLE_PATTERN *chart_label_key, SIMPLE_PATTERN *chart_labels_filter, SIMPLE_PATTERN *chart_dimensions);
+int rrdcontexts_to_json(RRDHOST *host, BUFFER *wb, time_t after, time_t before, RRDCONTEXT_TO_JSON_OPTIONS options, SIMPLE_PATTERN *chart_label_key, SIMPLE_PATTERN *chart_labels_filter, SIMPLE_PATTERN *chart_dimensions);
+
+// ----------------------------------------------------------------------------
+// public API for rrdcontexts
+
+const char *rrdcontext_acquired_id(RRDCONTEXT_ACQUIRED *rca);
 
 // ----------------------------------------------------------------------------
 // public API for rrddims
 
-extern void rrdcontext_updated_rrddim(RRDDIM *rd);
-extern void rrdcontext_removed_rrddim(RRDDIM *rd);
-extern void rrdcontext_updated_rrddim_algorithm(RRDDIM *rd);
-extern void rrdcontext_updated_rrddim_multiplier(RRDDIM *rd);
-extern void rrdcontext_updated_rrddim_divisor(RRDDIM *rd);
-extern void rrdcontext_updated_rrddim_flags(RRDDIM *rd);
-extern void rrdcontext_collected_rrddim(RRDDIM *rd);
+void rrdcontext_updated_rrddim(RRDDIM *rd);
+void rrdcontext_removed_rrddim(RRDDIM *rd);
+void rrdcontext_updated_rrddim_algorithm(RRDDIM *rd);
+void rrdcontext_updated_rrddim_multiplier(RRDDIM *rd);
+void rrdcontext_updated_rrddim_divisor(RRDDIM *rd);
+void rrdcontext_updated_rrddim_flags(RRDDIM *rd);
+void rrdcontext_collected_rrddim(RRDDIM *rd);
+int rrdcontext_find_dimension_uuid(RRDSET *st, const char *id, uuid_t *store_uuid);
 
 // ----------------------------------------------------------------------------
 // public API for rrdsets
 
-extern void rrdcontext_updated_rrdset(RRDSET *st);
-extern void rrdcontext_removed_rrdset(RRDSET *st);
-extern void rrdcontext_updated_rrdset_name(RRDSET *st);
-extern void rrdcontext_updated_rrdset_flags(RRDSET *st);
-extern void rrdcontext_collected_rrdset(RRDSET *st);
+void rrdcontext_updated_rrdset(RRDSET *st);
+void rrdcontext_removed_rrdset(RRDSET *st);
+void rrdcontext_updated_rrdset_name(RRDSET *st);
+void rrdcontext_updated_rrdset_flags(RRDSET *st);
+void rrdcontext_updated_retention_rrdset(RRDSET *st);
+void rrdcontext_collected_rrdset(RRDSET *st);
+int rrdcontext_find_chart_uuid(RRDSET *st, uuid_t *store_uuid);
 
 // ----------------------------------------------------------------------------
 // public API for ACLK
 
-extern void rrdcontext_hub_checkpoint_command(void *cmd);
-extern void rrdcontext_hub_stop_streaming_command(void *cmd);
+void rrdcontext_hub_checkpoint_command(void *cmd);
+void rrdcontext_hub_stop_streaming_command(void *cmd);
 
 
 // ----------------------------------------------------------------------------
 // public API for threads
 
-extern int rrdcontext_enabled;
+void rrdcontext_db_rotation(void);
+void *rrdcontext_main(void *);
+
+// ----------------------------------------------------------------------------
+// public API for weights
+
+struct metric_entry {
+    RRDCONTEXT_ACQUIRED *rca;
+    RRDINSTANCE_ACQUIRED *ria;
+    RRDMETRIC_ACQUIRED *rma;
+};
+
+DICTIONARY *rrdcontext_all_metrics_to_dict(RRDHOST *host, SIMPLE_PATTERN *contexts);
 
-extern void rrdcontext_db_rotation(void);
-extern void *rrdcontext_main(void *);
+// ----------------------------------------------------------------------------
+// public API for queries
+
+typedef struct query_metric {
+    struct query_metric_tier {
+        struct storage_engine *eng;
+        STORAGE_METRIC_HANDLE *db_metric_handle;
+        time_t db_first_time_t;         // the oldest timestamp available for this tier
+        time_t db_last_time_t;          // the latest timestamp available for this tier
+        time_t db_update_every;         // latest update every for this tier
+    } tiers[RRD_STORAGE_TIERS];
+
+    struct {
+        RRDHOST *host;
+        RRDCONTEXT_ACQUIRED *rca;
+        RRDINSTANCE_ACQUIRED *ria;
+        RRDMETRIC_ACQUIRED *rma;
+    } link;
+
+    struct {
+        STRING *id;
+        STRING *name;
+        RRDR_DIMENSION_FLAGS options;
+    } dimension;
+
+    struct {
+        STRING *id;
+        STRING *name;
+    } chart;
+
+} QUERY_METRIC;
+
+#define MAX_QUERY_TARGET_ID_LENGTH 255
+
+typedef struct query_target_request {
+    RRDHOST *host;                      // the host to be queried (can be NULL, hosts will be used)
+    RRDCONTEXT_ACQUIRED *rca;           // the context to be queried (can be NULL)
+    RRDINSTANCE_ACQUIRED *ria;          // the instance to be queried (can be NULL)
+    RRDMETRIC_ACQUIRED *rma;            // the metric to be queried (can be NULL)
+    RRDSET *st;                         // the chart to be queried (NULL, for context queries)
+    const char *hosts;                  // hosts simple pattern
+    const char *contexts;               // contexts simple pattern (context queries)
+    const char *charts;                 // charts simple pattern (for context queries)
+    const char *dimensions;             // dimensions simple pattern
+    const char *chart_label_key;        // select only the chart having this label key
+    const char *charts_labels_filter;   // select only the charts having this combo of label key:value
+    time_t after;                       // the requested timeframe
+    time_t before;                      // the requested timeframe
+    size_t points;                      // the requested number of points
+    time_t timeout;                     // the timeout of the query in seconds
+    uint32_t format;                    // DATASOURCE_FORMAT
+    RRDR_OPTIONS options;
+    RRDR_GROUPING group_method;
+    const char *group_options;
+    time_t resampling_time;
+    size_t tier;
+    QUERY_SOURCE query_source;
+} QUERY_TARGET_REQUEST;
+
+typedef struct query_target {
+    char id[MAX_QUERY_TARGET_ID_LENGTH + 1]; // query identifier (for logging)
+    QUERY_TARGET_REQUEST request;
+
+    bool used;                              // when true, this query is currently being used
+    size_t queries;                         // how many query we have done so far
+
+    struct {
+        bool relative;                      // true when the request made with relative timestamps, true if it was absolute
+        bool aligned;
+        time_t after;                       // the absolute timestamp this query is about
+        time_t before;                      // the absolute timestamp this query is about
+        time_t query_granularity;
+        size_t points;                        // the number of points the query will return (maybe different from the request)
+        size_t group;
+        RRDR_GROUPING group_method;
+        const char *group_options;
+        size_t resampling_group;
+        NETDATA_DOUBLE resampling_divisor;
+        RRDR_OPTIONS options;
+        size_t tier;
+    } window;
+
+    struct {
+        time_t first_time_t;                // the combined first_time_t of all metrics in the query, across all tiers
+        time_t last_time_t;                 // the combined last_time_T of all metrics in the query, across all tiers
+        time_t minimum_latest_update_every; // the min update every of the metrics in the query
+    } db;
+
+    struct {
+        QUERY_METRIC *array;                // the metrics to be queried (all of them should be queried, no exceptions)
+        uint32_t used;                      // how many items of the array are used
+        uint32_t size;                      // the size of the array
+        SIMPLE_PATTERN *pattern;
+    } query;
+
+    struct {
+        RRDMETRIC_ACQUIRED **array;
+        uint32_t used;                      // how many items of the array are used
+        uint32_t size;                      // the size of the array
+    } metrics;
+
+    struct {
+        RRDINSTANCE_ACQUIRED **array;
+        uint32_t used;                      // how many items of the array are used
+        uint32_t size;                      // the size of the array
+        SIMPLE_PATTERN *pattern;
+        SIMPLE_PATTERN *chart_label_key_pattern;
+        SIMPLE_PATTERN *charts_labels_filter_pattern;
+    } instances;
+
+    struct {
+        RRDCONTEXT_ACQUIRED **array;
+        uint32_t used;                      // how many items of the array are used
+        uint32_t size;                      // the size of the array
+        SIMPLE_PATTERN *pattern;
+    } contexts;
+
+    struct {
+        RRDHOST **array;
+        uint32_t used;                      // how many items of the array are used
+        uint32_t size;                      // the size of the array
+        SIMPLE_PATTERN *pattern;
+    } hosts;
+
+} QUERY_TARGET;
+
+void query_target_free(void);
+void query_target_release(QUERY_TARGET *qt);
+
+QUERY_TARGET *query_target_create(QUERY_TARGET_REQUEST *qtr);
 
 #endif // NETDATA_RRDCONTEXT_H
 
diff --git a/database/rrddim.c b/database/rrddim.c
index 90165a253..1b3d9952c 100644
--- a/database/rrddim.c
+++ b/database/rrddim.c
@@ -2,281 +2,117 @@
 
 #define NETDATA_RRD_INTERNALS
 #include "rrd.h"
-#ifdef ENABLE_DBENGINE
-#include "database/engine/rrdengineapi.h"
-#endif
 #include "storage_engine.h"
 
 // ----------------------------------------------------------------------------
 // RRDDIM index
 
-int rrddim_compare(void* a, void* b) {
-    if(((RRDDIM *)a)->hash < ((RRDDIM *)b)->hash) return -1;
-    else if(((RRDDIM *)a)->hash > ((RRDDIM *)b)->hash) return 1;
-    else return strcmp(((RRDDIM *)a)->id, ((RRDDIM *)b)->id);
-}
-
-#define rrddim_index_add(st, rd) (RRDDIM *)avl_insert_lock(&((st)->dimensions_index), (avl_t *)(rd))
-#define rrddim_index_del(st,rd ) (RRDDIM *)avl_remove_lock(&((st)->dimensions_index), (avl_t *)(rd))
-
-static inline RRDDIM *rrddim_index_find(RRDSET *st, const char *id, uint32_t hash) {
-    RRDDIM tmp = {
-            .id = id,
-            .hash = (hash)?hash:simple_hash(id)
-    };
-    return (RRDDIM *)avl_search_lock(&(st->dimensions_index), (avl_t *) &tmp);
-}
-
-
-// ----------------------------------------------------------------------------
-// RRDDIM - find a dimension
-
-inline RRDDIM *rrddim_find(RRDSET *st, const char *id) {
-    debug(D_RRD_CALLS, "rrddim_find() for chart %s, dimension %s", st->name, id);
-
-    return rrddim_index_find(st, id, 0);
-}
-
-
-// ----------------------------------------------------------------------------
-// RRDDIM rename a dimension
-
-inline int rrddim_set_name(RRDSET *st, RRDDIM *rd, const char *name) {
-    if(unlikely(!name || !*name || (rd->name && !strcmp(rd->name, name))))
-        return 0;
-
-    debug(D_RRD_CALLS, "rrddim_set_name() from %s.%s to %s.%s", st->name, rd->name, st->name, name);
-
-    if (rd->name)
-        freez((void *) rd->name);
-
-    rd->name = strdupz(name);
-    rd->hash_name = simple_hash(rd->name);
-
-    if (!st->state->is_ar_chart)
-        rrddimvar_rename_all(rd);
-
-    rd->exposed = 0;
-    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
-
-    ml_dimension_update_name(st, rd, name);
-
-    return 1;
-}
-
-inline int rrddim_set_algorithm(RRDSET *st, RRDDIM *rd, RRD_ALGORITHM algorithm) {
-    if(unlikely(rd->algorithm == algorithm))
-        return 0;
-
-    debug(D_RRD_CALLS, "Updating algorithm of dimension '%s/%s' from %s to %s", st->id, rd->name, rrd_algorithm_name(rd->algorithm), rrd_algorithm_name(algorithm));
-    rd->algorithm = algorithm;
-    rd->exposed = 0;
-    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
-    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
-    rrdcontext_updated_rrddim_algorithm(rd);
-    return 1;
-}
-
-inline int rrddim_set_multiplier(RRDSET *st, RRDDIM *rd, collected_number multiplier) {
-    if(unlikely(rd->multiplier == multiplier))
-        return 0;
+struct rrddim_constructor {
+    RRDSET *st;
+    const char *id;
+    const char *name;
+    collected_number multiplier;
+    collected_number divisor;
+    RRD_ALGORITHM algorithm;
+    RRD_MEMORY_MODE memory_mode;
+
+    enum {
+        RRDDIM_REACT_NONE    = 0,
+        RRDDIM_REACT_NEW     = (1 << 0),
+        RRDDIM_REACT_UPDATED = (1 << 2),
+    } react_action;
 
-    debug(D_RRD_CALLS, "Updating multiplier of dimension '%s/%s' from " COLLECTED_NUMBER_FORMAT " to " COLLECTED_NUMBER_FORMAT, st->id, rd->name, rd->multiplier, multiplier);
-    rd->multiplier = multiplier;
-    rd->exposed = 0;
-    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
-    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
-    rrdcontext_updated_rrddim_multiplier(rd);
-    return 1;
-}
-
-inline int rrddim_set_divisor(RRDSET *st, RRDDIM *rd, collected_number divisor) {
-    if(unlikely(rd->divisor == divisor))
-        return 0;
-
-    debug(D_RRD_CALLS, "Updating divisor of dimension '%s/%s' from " COLLECTED_NUMBER_FORMAT " to " COLLECTED_NUMBER_FORMAT, st->id, rd->name, rd->divisor, divisor);
-    rd->divisor = divisor;
-    rd->exposed = 0;
-    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
-    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
-    rrdcontext_updated_rrddim_divisor(rd);
-    return 1;
-}
-
-// ----------------------------------------------------------------------------
-// RRDDIM create a dimension
-
-void rrdcalc_link_to_rrddim(RRDDIM *rd, RRDSET *st, RRDHOST *host) {
-    RRDCALC *rrdc;
-    
-    for (rrdc = host->alarms_with_foreach; rrdc ; rrdc = rrdc->next) {
-        if (simple_pattern_matches(rrdc->spdim, rd->id) || simple_pattern_matches(rrdc->spdim, rd->name)) {
-            if (rrdc->hash_chart == st->hash_name || !strcmp(rrdc->chart, st->name) || !strcmp(rrdc->chart, st->id)) {
-                char *name = alarm_name_with_dim(rrdc->name, strlen(rrdc->name), rd->name, strlen(rd->name));
-                if(rrdcalc_exists(host, st->name, name, 0, 0)) {
-                    freez(name);
-                    continue;
-                }
-
-                netdata_rwlock_wrlock(&host->health_log.alarm_log_rwlock);
-                RRDCALC *child = rrdcalc_create_from_rrdcalc(rrdc, host, name, rd->name);
-                netdata_rwlock_unlock(&host->health_log.alarm_log_rwlock);
-
-                if (child) {
-                    rrdcalc_add_to_host(host, child);
-                    RRDCALC *rdcmp  = (RRDCALC *) avl_insert_lock(&(host)->alarms_idx_health_log,(avl_t *)child);
-                    if (rdcmp != child) {
-                        error("Cannot insert the alarm index ID %s",child->name);
-                    }
-                }
-                else {
-                    error("Cannot allocate a new alarm.");
-                    rrdc->foreachcounter--;
-                }
-            }
-        }
-    }
-}
-
-// Return either
-//   0 : Dimension is live
-//   last collected time : Dimension is not live
+};
 
-#ifdef ENABLE_ACLK
-time_t calc_dimension_liveness(RRDDIM *rd, time_t now)
-{
-    time_t last_updated = rd->last_collected_time.tv_sec;
-    int live;
-    if (rd->aclk_live_status == 1)
-        live =
-            ((now - last_updated) <
-             MIN(rrdset_free_obsolete_time, RRDSET_MINIMUM_DIM_OFFLINE_MULTIPLIER * rd->update_every));
-    else
-        live = ((now - last_updated) < RRDSET_MINIMUM_DIM_LIVE_MULTIPLIER * rd->update_every);
-    return live ? 0 : last_updated;
+// isolated call to appear
+// separate in statistics
+static void *rrddim_alloc_db(size_t entries) {
+    return callocz(entries, sizeof(storage_number));
 }
-#endif
 
-RRDDIM *rrddim_add_custom(RRDSET *st, const char *id, const char *name, collected_number multiplier,
-                          collected_number divisor, RRD_ALGORITHM algorithm, RRD_MEMORY_MODE memory_mode)
-{
+static void rrddim_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddim, void *constructor_data) {
+    struct rrddim_constructor *ctr = constructor_data;
+    RRDDIM *rd = rrddim;
+    RRDSET *st = ctr->st;
     RRDHOST *host = st->rrdhost;
-    rrdset_wrlock(st);
 
-    RRDDIM *rd = rrddim_find(st, id);
-    if(unlikely(rd)) {
-        debug(D_RRD_CALLS, "Cannot create rrd dimension '%s/%s', it already exists.", st->id, name?name:"<NONAME>");
-
-        int rc = rrddim_set_name(st, rd, name);
-        rc += rrddim_set_algorithm(st, rd, algorithm);
-        rc += rrddim_set_multiplier(st, rd, multiplier);
-        rc += rrddim_set_divisor(st, rd, divisor);
-
-        if (rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)) {
-            store_active_dimension(&rd->metric_uuid);
-
-            for(int tier = 0; tier < storage_tiers ;tier++) {
-                if (rd->tiers[tier])
-                    rd->tiers[tier]->db_collection_handle =
-                        rd->tiers[tier]->collect_ops.init(rd->tiers[tier]->db_metric_handle);
-            }
-
-            rrddim_flag_clear(rd, RRDDIM_FLAG_ARCHIVED);
-            rrddimvar_create(rd, RRDVAR_TYPE_CALCULATED, NULL, NULL, &rd->last_stored_value, RRDVAR_OPTION_DEFAULT);
-            rrddimvar_create(rd, RRDVAR_TYPE_COLLECTED, NULL, "_raw", &rd->last_collected_value, RRDVAR_OPTION_DEFAULT);
-            rrddimvar_create(rd, RRDVAR_TYPE_TIME_T, NULL, "_last_collected_t", &rd->last_collected_time.tv_sec, RRDVAR_OPTION_DEFAULT);
+    rd->flags = RRDDIM_FLAG_NONE;
 
-            rrddim_flag_set(rd, RRDDIM_FLAG_PENDING_FOREACH_ALARM);
-            rrdset_flag_set(st, RRDSET_FLAG_PENDING_FOREACH_ALARMS);
-            rrdhost_flag_set(host, RRDHOST_FLAG_PENDING_FOREACH_ALARMS);
-        }
+    rd->id = string_strdupz(ctr->id);
+    rd->name = (ctr->name && *ctr->name)?rrd_string_strdupz(ctr->name):string_dup(rd->id);
 
-        if (unlikely(rc)) {
-            debug(D_METADATALOG, "DIMENSION [%s] metadata updated", rd->id);
-            (void)sql_store_dimension(&rd->metric_uuid, rd->rrdset->chart_uuid, rd->id, rd->name, rd->multiplier, rd->divisor,
-                                      rd->algorithm);
-#ifdef ENABLE_ACLK
-            queue_dimension_to_aclk(rd, calc_dimension_liveness(rd, now_realtime_sec()));
-#endif
-            rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
-            rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
-        }
-        rrdset_unlock(st);
-        rrdcontext_updated_rrddim(rd);
-        return rd;
-    }
-
-    rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
-    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
-
-    rd = callocz(1, sizeof(RRDDIM));
-    rd->id = strdupz(id);
-    rd->hash = simple_hash(rd->id);
-
-    rd->name = (name && *name)?strdupz(name):strdupz(rd->id);
-    rd->hash_name = simple_hash(rd->name);
-
-    rd->algorithm = algorithm;
-    rd->multiplier = multiplier;
-    rd->divisor = divisor;
+    rd->algorithm = ctr->algorithm;
+    rd->multiplier = ctr->multiplier;
+    rd->divisor = ctr->divisor;
     if(!rd->divisor) rd->divisor = 1;
 
-    rd->entries = st->entries;
     rd->update_every = st->update_every;
 
+    rd->rrdset = st;
+
     if(rrdset_flag_check(st, RRDSET_FLAG_STORE_FIRST))
         rd->collections_counter = 1;
 
-    rd->rrdset = st;
-
-    if(memory_mode == RRD_MEMORY_MODE_MAP || memory_mode == RRD_MEMORY_MODE_SAVE) {
-        if(!rrddim_memory_load_or_create_map_save(st, rd, memory_mode)) {
-            info("Failed to use memory mode %s for chart '%s', dimension '%s', falling back to ram", (memory_mode == RRD_MEMORY_MODE_MAP)?"map":"save", st->name, rd->name);
-            memory_mode = RRD_MEMORY_MODE_RAM;
+    if(ctr->memory_mode == RRD_MEMORY_MODE_MAP || ctr->memory_mode == RRD_MEMORY_MODE_SAVE) {
+        if(!rrddim_memory_load_or_create_map_save(st, rd, ctr->memory_mode)) {
+            info("Failed to use memory mode %s for chart '%s', dimension '%s', falling back to ram", (ctr->memory_mode == RRD_MEMORY_MODE_MAP)?"map":"save", rrdset_name(st), rrddim_name(rd));
+            ctr->memory_mode = RRD_MEMORY_MODE_RAM;
         }
     }
 
-    if(memory_mode == RRD_MEMORY_MODE_RAM) {
+    if(ctr->memory_mode == RRD_MEMORY_MODE_RAM) {
         size_t entries = st->entries;
         if(!entries) entries = 5;
 
         rd->db = netdata_mmap(NULL, entries * sizeof(storage_number), MAP_PRIVATE, 1);
         if(!rd->db) {
-            info("Failed to use memory mode ram for chart '%s', dimension '%s', falling back to alloc", st->name, rd->name);
-            memory_mode = RRD_MEMORY_MODE_ALLOC;
+            info("Failed to use memory mode ram for chart '%s', dimension '%s', falling back to alloc", rrdset_name(st), rrddim_name(rd));
+            ctr->memory_mode = RRD_MEMORY_MODE_ALLOC;
         }
         else rd->memsize = entries * sizeof(storage_number);
     }
 
-    if(memory_mode == RRD_MEMORY_MODE_ALLOC || memory_mode == RRD_MEMORY_MODE_NONE) {
+    if(ctr->memory_mode == RRD_MEMORY_MODE_ALLOC || ctr->memory_mode == RRD_MEMORY_MODE_NONE) {
         size_t entries = st->entries;
         if(entries < 5) entries = 5;
 
-        rd->db = callocz(entries, sizeof(storage_number));
+        rd->db = rrddim_alloc_db(entries);
         rd->memsize = entries * sizeof(storage_number);
     }
 
-    rd->rrd_memory_mode = memory_mode;
-
-#ifdef ENABLE_ACLK
-    rd->aclk_live_status = -1;
+    rd->rrd_memory_mode = ctr->memory_mode;
+
+    if (unlikely(rrdcontext_find_dimension_uuid(st, rrddim_id(rd), &(rd->metric_uuid)))) {
+        uuid_generate(rd->metric_uuid);
+        bool found_in_sql = false; (void)found_in_sql;
+
+//        bool found_in_sql = true;
+//        if(unlikely(sql_find_dimension_uuid(st, rd, &rd->metric_uuid))) {
+//            found_in_sql = false;
+//            uuid_generate(rd->metric_uuid);
+//        }
+
+#ifdef NETDATA_INTERNAL_CHECKS
+        char uuid_str[UUID_STR_LEN];
+        uuid_unparse_lower(rd->metric_uuid, uuid_str);
+        error_report("Dimension UUID for host %s chart [%s] dimension [%s] not found in context. It is now set to %s (%s)",
+                     string2str(host->hostname),
+                     string2str(st->name),
+                     string2str(rd->name),
+                     uuid_str, found_in_sql ? "found in sqlite" : "newly generated");
 #endif
-    (void) find_dimension_uuid(st, rd, &(rd->metric_uuid));
+    }
 
     // initialize the db tiers
     {
         size_t initialized = 0;
-        RRD_MEMORY_MODE wanted_mode = memory_mode;
-        for(int tier = 0; tier < storage_tiers ; tier++, wanted_mode = RRD_MEMORY_MODE_DBENGINE) {
-            STORAGE_ENGINE *eng = storage_engine_get(wanted_mode);
-            if(!eng) continue;
-
+        for(size_t tier = 0; tier < storage_tiers ; tier++) {
+            STORAGE_ENGINE *eng = host->db[tier].eng;
             rd->tiers[tier] = callocz(1, sizeof(struct rrddim_tier));
-            rd->tiers[tier]->tier_grouping = get_tier_grouping(tier);
-            rd->tiers[tier]->mode = eng->id;
-            rd->tiers[tier]->collect_ops = eng->api.collect_ops;
-            rd->tiers[tier]->query_ops = eng->api.query_ops;
-            rd->tiers[tier]->db_metric_handle = eng->api.init(rd, host->storage_instance[tier]);
+            rd->tiers[tier]->tier_grouping = host->db[tier].tier_grouping;
+            rd->tiers[tier]->collect_ops = &eng->api.collect_ops;
+            rd->tiers[tier]->query_ops = &eng->api.query_ops;
+            rd->tiers[tier]->db_metric_handle = eng->api.metric_get_or_create(rd, host->db[tier].instance, rd->rrdset->storage_metrics_groups[tier]);
             storage_point_unset(rd->tiers[tier]->virtual_point);
             initialized++;
 
@@ -284,138 +120,114 @@ RRDDIM *rrddim_add_custom(RRDSET *st, const char *id, const char *name, collecte
         }
 
         if(!initialized)
-            error("Failed to initialize all db tiers for chart '%s', dimension '%s", st->name, rd->name);
+            error("Failed to initialize all db tiers for chart '%s', dimension '%s", rrdset_name(st), rrddim_name(rd));
 
         if(!rd->tiers[0])
-            error("Failed to initialize the first db tier for chart '%s', dimension '%s", st->name, rd->name);
+            error("Failed to initialize the first db tier for chart '%s', dimension '%s", rrdset_name(st), rrddim_name(rd));
     }
 
-    store_active_dimension(&rd->metric_uuid);
-
     // initialize data collection for all tiers
     {
         size_t initialized = 0;
-        for (int tier = 0; tier < storage_tiers; tier++) {
+        for (size_t tier = 0; tier < storage_tiers; tier++) {
             if (rd->tiers[tier]) {
-                rd->tiers[tier]->db_collection_handle = rd->tiers[tier]->collect_ops.init(rd->tiers[tier]->db_metric_handle);
+                rd->tiers[tier]->db_collection_handle = rd->tiers[tier]->collect_ops->init(rd->tiers[tier]->db_metric_handle, st->rrdhost->db[tier].tier_grouping * st->update_every);
                 initialized++;
             }
         }
 
         if(!initialized)
-            error("Failed to initialize data collection for all db tiers for chart '%s', dimension '%s", st->name, rd->name);
+            error("Failed to initialize data collection for all db tiers for chart '%s', dimension '%s", rrdset_name(st), rrddim_name(rd));
     }
 
-    // append this dimension
-    if(!st->dimensions)
-        st->dimensions = rd;
-    else {
-        RRDDIM *td = st->dimensions;
+    if(rrdset_number_of_dimensions(st) != 0) {
+        RRDDIM *td;
+        dfe_start_write(st->rrddim_root_index, td) {
+            if(!td) break;
+        }
+        dfe_done(td);
 
-        if(td->algorithm != rd->algorithm || ABS(td->multiplier) != ABS(rd->multiplier) || ABS(td->divisor) != ABS(rd->divisor)) {
+        if(td && (td->algorithm != rd->algorithm || ABS(td->multiplier) != ABS(rd->multiplier) || ABS(td->divisor) != ABS(rd->divisor))) {
             if(!rrdset_flag_check(st, RRDSET_FLAG_HETEROGENEOUS)) {
-                #ifdef NETDATA_INTERNAL_CHECKS
+#ifdef NETDATA_INTERNAL_CHECKS
                 info("Dimension '%s' added on chart '%s' of host '%s' is not homogeneous to other dimensions already present (algorithm is '%s' vs '%s', multiplier is " COLLECTED_NUMBER_FORMAT " vs " COLLECTED_NUMBER_FORMAT ", divisor is " COLLECTED_NUMBER_FORMAT " vs " COLLECTED_NUMBER_FORMAT ").",
-                        rd->name,
-                        st->name,
-                        host->hostname,
-                        rrd_algorithm_name(rd->algorithm), rrd_algorithm_name(td->algorithm),
-                        rd->multiplier, td->multiplier,
-                        rd->divisor, td->divisor
+                     rrddim_name(rd),
+                     rrdset_name(st),
+                     rrdhost_hostname(host),
+                     rrd_algorithm_name(rd->algorithm), rrd_algorithm_name(td->algorithm),
+                     rd->multiplier, td->multiplier,
+                     rd->divisor, td->divisor
                 );
-                #endif
+#endif
                 rrdset_flag_set(st, RRDSET_FLAG_HETEROGENEOUS);
             }
         }
-
-        for(; td->next; td = td->next) ;
-        td->next = rd;
-    }
-
-    if(host->health_enabled && !st->state->is_ar_chart) {
-        rrddimvar_create(rd, RRDVAR_TYPE_CALCULATED, NULL, NULL, &rd->last_stored_value, RRDVAR_OPTION_DEFAULT);
-        rrddimvar_create(rd, RRDVAR_TYPE_COLLECTED, NULL, "_raw", &rd->last_collected_value, RRDVAR_OPTION_DEFAULT);
-        rrddimvar_create(rd, RRDVAR_TYPE_TIME_T, NULL, "_last_collected_t", &rd->last_collected_time.tv_sec, RRDVAR_OPTION_DEFAULT);
     }
 
-    if(unlikely(rrddim_index_add(st, rd) != rd))
-        error("RRDDIM: INTERNAL ERROR: attempt to index duplicate dimension '%s' on chart '%s'", rd->id, st->id);
+    rrddim_flag_set(rd, RRDDIM_FLAG_PENDING_HEALTH_INITIALIZATION);
+    rrdset_flag_set(rd->rrdset, RRDSET_FLAG_PENDING_HEALTH_INITIALIZATION);
+    rrdhost_flag_set(rd->rrdset->rrdhost, RRDHOST_FLAG_PENDING_HEALTH_INITIALIZATION);
 
-    rrddim_flag_set(rd, RRDDIM_FLAG_PENDING_FOREACH_ALARM);
-    rrdset_flag_set(st, RRDSET_FLAG_PENDING_FOREACH_ALARMS);
-    rrdhost_flag_set(host, RRDHOST_FLAG_PENDING_FOREACH_ALARMS);
+    // let the chart resync
+    rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
+    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
 
     ml_new_dimension(rd);
 
-    rrdset_unlock(st);
-    rrdcontext_updated_rrddim(rd);
-    return(rd);
+    ctr->react_action = RRDDIM_REACT_NEW;
+
+    internal_error(false, "RRDDIM: inserted dimension '%s' of chart '%s' of host '%s'",
+                   rrddim_name(rd), rrdset_name(st), rrdhost_hostname(st->rrdhost));
+
 }
 
-// ----------------------------------------------------------------------------
-// RRDDIM remove / free a dimension
+static void rrddim_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddim, void *rrdset) {
+    RRDDIM *rd = rrddim;
+    RRDSET *st = rrdset;
+    RRDHOST *host = st->rrdhost;
+
+    internal_error(false, "RRDDIM: deleting dimension '%s' of chart '%s' of host '%s'",
+                   rrddim_name(rd), rrdset_name(st), rrdhost_hostname(host));
 
-void rrddim_free(RRDSET *st, RRDDIM *rd)
-{
     rrdcontext_removed_rrddim(rd);
-    ml_delete_dimension(rd);
-    
-    debug(D_RRD_CALLS, "rrddim_free() %s.%s", st->name, rd->name);
 
-    if (!rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)) {
+    ml_delete_dimension(rd);
 
-        size_t tiers_available = 0, tiers_said_yes = 0;
-        for(int tier = 0; tier < storage_tiers ;tier++) {
-            if(rd->tiers[tier]) {
-                tiers_available++;
+    debug(D_RRD_CALLS, "rrddim_free() %s.%s", rrdset_name(st), rrddim_name(rd));
 
-                if(rd->tiers[tier]->collect_ops.finalize(rd->tiers[tier]->db_collection_handle))
-                    tiers_said_yes++;
+    size_t tiers_available = 0, tiers_said_yes = 0;
+    for(size_t tier = 0; tier < storage_tiers ;tier++) {
+        if(rd->tiers[tier] && rd->tiers[tier]->db_collection_handle) {
+            tiers_available++;
 
-                rd->tiers[tier]->db_collection_handle = NULL;
-            }
-        }
+            if(rd->tiers[tier]->collect_ops->finalize(rd->tiers[tier]->db_collection_handle))
+                tiers_said_yes++;
 
-        if (tiers_available == tiers_said_yes && tiers_said_yes && rd->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE) {
-            /* This metric has no data and no references */
-            delete_dimension_uuid(&rd->metric_uuid);
+            rd->tiers[tier]->db_collection_handle = NULL;
         }
     }
 
-    if(rd == st->dimensions)
-        st->dimensions = rd->next;
-    else {
-        RRDDIM *i;
-        for (i = st->dimensions; i && i->next != rd; i = i->next) ;
-
-        if (i && i->next == rd)
-            i->next = rd->next;
-        else
-            error("Request to free dimension '%s.%s' but it is not linked.", st->id, rd->name);
+    if (tiers_available == tiers_said_yes && tiers_said_yes && rd->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE) {
+        /* This metric has no data and no references */
+        metaqueue_delete_dimension_uuid(&rd->metric_uuid);
     }
-    rd->next = NULL;
 
-    while(rd->variables)
-        rrddimvar_free(rd->variables);
-
-    if(unlikely(rrddim_index_del(st, rd) != rd))
-        error("RRDDIM: INTERNAL ERROR: attempt to remove from index dimension '%s' on chart '%s', removed a different dimension.", rd->id, st->id);
+    rrddimvar_delete_all(rd);
 
     // free(rd->annotations);
-//#ifdef ENABLE_ACLK
-//    if (!netdata_exit)
-//        aclk_send_dimension_update(rd);
-//#endif
+    //#ifdef ENABLE_ACLK
+    //    if (!netdata_exit)
+    //        aclk_send_dimension_update(rd);
+    //#endif
 
     // this will free MEMORY_MODE_SAVE and MEMORY_MODE_MAP structures
     rrddim_memory_file_free(rd);
 
-    for(int tier = 0; tier < storage_tiers ;tier++) {
+    for(size_t tier = 0; tier < storage_tiers ;tier++) {
         if(!rd->tiers[tier]) continue;
 
-        STORAGE_ENGINE* eng = storage_engine_get(rd->tiers[tier]->mode);
-        if(eng)
-            eng->api.free(rd->tiers[tier]->db_metric_handle);
+        STORAGE_ENGINE* eng = host->db[tier].eng;
+        eng->api.metric_release(rd->tiers[tier]->db_metric_handle);
 
         freez(rd->tiers[tier]);
         rd->tiers[tier] = NULL;
@@ -423,14 +235,252 @@ void rrddim_free(RRDSET *st, RRDDIM *rd)
 
     if(rd->db) {
         if(rd->rrd_memory_mode == RRD_MEMORY_MODE_RAM)
-            munmap(rd->db, rd->memsize);
+            netdata_munmap(rd->db, rd->memsize);
         else
             freez(rd->db);
     }
 
-    freez((void *)rd->id);
-    freez((void *)rd->name);
-    freez(rd);
+    string_freez(rd->id);
+    string_freez(rd->name);
+}
+
+static bool rrddim_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddim, void *new_rrddim, void *constructor_data) {
+    (void)new_rrddim; // it is NULL
+
+    struct rrddim_constructor *ctr = constructor_data;
+    RRDDIM *rd = rrddim;
+    RRDSET *st = ctr->st;
+
+    ctr->react_action = RRDDIM_REACT_NONE;
+
+    int rc = rrddim_reset_name(st, rd, ctr->name);
+    rc += rrddim_set_algorithm(st, rd, ctr->algorithm);
+    rc += rrddim_set_multiplier(st, rd, ctr->multiplier);
+    rc += rrddim_set_divisor(st, rd, ctr->divisor);
+
+    for(size_t tier = 0; tier < storage_tiers ;tier++) {
+        if (rd->tiers[tier] && !rd->tiers[tier]->db_collection_handle)
+            rd->tiers[tier]->db_collection_handle =
+                rd->tiers[tier]->collect_ops->init(rd->tiers[tier]->db_metric_handle, st->rrdhost->db[tier].tier_grouping * st->update_every);
+    }
+
+    if(rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)) {
+        rrddim_flag_clear(rd, RRDDIM_FLAG_ARCHIVED);
+
+        rrddim_flag_set(rd, RRDDIM_FLAG_PENDING_HEALTH_INITIALIZATION);
+        rrdset_flag_set(rd->rrdset, RRDSET_FLAG_PENDING_HEALTH_INITIALIZATION);
+        rrdhost_flag_set(rd->rrdset->rrdhost, RRDHOST_FLAG_PENDING_HEALTH_INITIALIZATION);
+    }
+
+    if(unlikely(rc))
+        ctr->react_action = RRDDIM_REACT_UPDATED;
+
+    return ctr->react_action == RRDDIM_REACT_UPDATED;
+}
+
+static void rrddim_react_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddim, void *constructor_data) {
+    struct rrddim_constructor *ctr = constructor_data;
+    RRDDIM *rd = rrddim;
+    RRDSET *st = ctr->st;
+
+    if(ctr->react_action & (RRDDIM_REACT_UPDATED | RRDDIM_REACT_NEW)) {
+        rrddim_flag_set(rd, RRDDIM_FLAG_METADATA_UPDATE);
+        rrdset_flag_set(rd->rrdset, RRDSET_FLAG_METADATA_UPDATE);
+        rrdhost_flag_set(rd->rrdset->rrdhost, RRDHOST_FLAG_METADATA_UPDATE);
+    }
+
+    if(ctr->react_action == RRDDIM_REACT_UPDATED) {
+        // the chart needs to be updated to the parent
+        rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
+        rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
+    }
+
+    rrdcontext_updated_rrddim(rd);
+}
+
+void rrddim_index_init(RRDSET *st) {
+    if(!st->rrddim_root_index) {
+        st->rrddim_root_index = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
+
+        dictionary_register_insert_callback(st->rrddim_root_index, rrddim_insert_callback, NULL);
+        dictionary_register_conflict_callback(st->rrddim_root_index, rrddim_conflict_callback, NULL);
+        dictionary_register_delete_callback(st->rrddim_root_index, rrddim_delete_callback, st);
+        dictionary_register_react_callback(st->rrddim_root_index, rrddim_react_callback, st);
+    }
+}
+
+void rrddim_index_destroy(RRDSET *st) {
+    dictionary_destroy(st->rrddim_root_index);
+    st->rrddim_root_index = NULL;
+}
+
+static inline RRDDIM *rrddim_index_find(RRDSET *st, const char *id) {
+    return dictionary_get(st->rrddim_root_index, id);
+}
+
+// ----------------------------------------------------------------------------
+// RRDDIM - find a dimension
+
+inline RRDDIM *rrddim_find(RRDSET *st, const char *id) {
+    debug(D_RRD_CALLS, "rrddim_find() for chart %s, dimension %s", rrdset_name(st), id);
+
+    return rrddim_index_find(st, id);
+}
+
+inline RRDDIM_ACQUIRED *rrddim_find_and_acquire(RRDSET *st, const char *id) {
+    debug(D_RRD_CALLS, "rrddim_find() for chart %s, dimension %s", rrdset_name(st), id);
+
+    return (RRDDIM_ACQUIRED *)dictionary_get_and_acquire_item(st->rrddim_root_index, id);
+}
+
+RRDDIM *rrddim_acquired_to_rrddim(RRDDIM_ACQUIRED *rda) {
+    if(unlikely(!rda))
+        return NULL;
+
+    return (RRDDIM *) dictionary_acquired_item_value((const DICTIONARY_ITEM *)rda);
+}
+
+void rrddim_acquired_release(RRDDIM_ACQUIRED *rda) {
+    if(unlikely(!rda))
+        return;
+
+    RRDDIM *rd = rrddim_acquired_to_rrddim(rda);
+    dictionary_acquired_item_release(rd->rrdset->rrddim_root_index, (const DICTIONARY_ITEM *)rda);
+}
+
+// This will not return dimensions that are archived
+RRDDIM *rrddim_find_active(RRDSET *st, const char *id) {
+    RRDDIM *rd = rrddim_find(st, id);
+
+    if (unlikely(rd && rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)))
+        return NULL;
+
+    return rd;
+}
+
+// ----------------------------------------------------------------------------
+// RRDDIM rename a dimension
+
+inline int rrddim_reset_name(RRDSET *st, RRDDIM *rd, const char *name) {
+    if(unlikely(!name || !*name || !strcmp(rrddim_name(rd), name)))
+        return 0;
+
+    debug(D_RRD_CALLS, "rrddim_reset_name() from %s.%s to %s.%s", rrdset_name(st), rrddim_name(rd), rrdset_name(st), name);
+
+    STRING *old = rd->name;
+    rd->name = rrd_string_strdupz(name);
+    string_freez(old);
+
+    rrddimvar_rename_all(rd);
+
+    rd->exposed = 0;
+    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
+
+    return 1;
+}
+
+inline int rrddim_set_algorithm(RRDSET *st, RRDDIM *rd, RRD_ALGORITHM algorithm) {
+    if(unlikely(rd->algorithm == algorithm))
+        return 0;
+
+    debug(D_RRD_CALLS, "Updating algorithm of dimension '%s/%s' from %s to %s", rrdset_id(st), rrddim_name(rd), rrd_algorithm_name(rd->algorithm), rrd_algorithm_name(algorithm));
+    rd->algorithm = algorithm;
+    rd->exposed = 0;
+    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
+    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
+    rrdcontext_updated_rrddim_algorithm(rd);
+    return 1;
+}
+
+inline int rrddim_set_multiplier(RRDSET *st, RRDDIM *rd, collected_number multiplier) {
+    if(unlikely(rd->multiplier == multiplier))
+        return 0;
+
+    debug(D_RRD_CALLS, "Updating multiplier of dimension '%s/%s' from " COLLECTED_NUMBER_FORMAT " to " COLLECTED_NUMBER_FORMAT, rrdset_id(st), rrddim_name(rd), rd->multiplier, multiplier);
+    rd->multiplier = multiplier;
+    rd->exposed = 0;
+    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
+    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
+    rrdcontext_updated_rrddim_multiplier(rd);
+    return 1;
+}
+
+inline int rrddim_set_divisor(RRDSET *st, RRDDIM *rd, collected_number divisor) {
+    if(unlikely(rd->divisor == divisor))
+        return 0;
+
+    debug(D_RRD_CALLS, "Updating divisor of dimension '%s/%s' from " COLLECTED_NUMBER_FORMAT " to " COLLECTED_NUMBER_FORMAT, rrdset_id(st), rrddim_name(rd), rd->divisor, divisor);
+    rd->divisor = divisor;
+    rd->exposed = 0;
+    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
+    rrdset_flag_set(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
+    rrdcontext_updated_rrddim_divisor(rd);
+    return 1;
+}
+
+// ----------------------------------------------------------------------------
+
+// get the timestamp of the last entry in the round-robin database
+time_t rrddim_last_entry_t(RRDDIM *rd) {
+    time_t latest = rd->tiers[0]->query_ops->latest_time(rd->tiers[0]->db_metric_handle);
+
+    for(size_t tier = 1; tier < storage_tiers ;tier++) {
+        if(unlikely(!rd->tiers[tier])) continue;
+
+        time_t t = rd->tiers[tier]->query_ops->latest_time(rd->tiers[tier]->db_metric_handle);
+        if(t > latest)
+            latest = t;
+    }
+
+    return latest;
+}
+
+time_t rrddim_first_entry_t_of_tier(RRDDIM *rd, size_t tier) {
+    if(unlikely(tier > storage_tiers || !rd->tiers[tier]))
+        return 0;
+
+    return rd->tiers[tier]->query_ops->oldest_time(rd->tiers[tier]->db_metric_handle);
+}
+
+time_t rrddim_first_entry_t(RRDDIM *rd) {
+    time_t oldest = 0;
+
+    for(size_t tier = 0; tier < storage_tiers ;tier++) {
+        time_t t = rrddim_first_entry_t_of_tier(rd, tier);
+        if(t != 0 && (oldest == 0 || t < oldest))
+            oldest = t;
+    }
+
+    return oldest;
+}
+
+RRDDIM *rrddim_add_custom(RRDSET *st
+                          , const char *id
+                          , const char *name
+                          , collected_number multiplier
+                          , collected_number divisor
+                          , RRD_ALGORITHM algorithm
+                          , RRD_MEMORY_MODE memory_mode
+                          ) {
+    struct rrddim_constructor tmp = {
+        .st = st,
+        .id = id,
+        .name = name,
+        .multiplier = multiplier,
+        .divisor = divisor,
+        .algorithm = algorithm,
+        .memory_mode = memory_mode,
+    };
+
+    RRDDIM *rd = dictionary_set_advanced(st->rrddim_root_index, tmp.id, -1, NULL, sizeof(RRDDIM), &tmp);
+    return(rd);
+}
+
+// ----------------------------------------------------------------------------
+// RRDDIM remove / free a dimension
+
+void rrddim_free(RRDSET *st, RRDDIM *rd) {
+    dictionary_del(st->rrddim_root_index, string2str(rd->id));
 }
 
 
@@ -438,56 +488,59 @@ void rrddim_free(RRDSET *st, RRDDIM *rd)
 // RRDDIM - set dimension options
 
 int rrddim_hide(RRDSET *st, const char *id) {
-    debug(D_RRD_CALLS, "rrddim_hide() for chart %s, dimension %s", st->name, id);
+    debug(D_RRD_CALLS, "rrddim_hide() for chart %s, dimension %s", rrdset_name(st), id);
 
     RRDHOST *host = st->rrdhost;
 
     RRDDIM *rd = rrddim_find(st, id);
     if(unlikely(!rd)) {
-        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, st->name, st->id, host->hostname);
+        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, rrdset_name(st), rrdset_id(st), rrdhost_hostname(host));
         return 1;
     }
-    if (!rrddim_flag_check(rd, RRDDIM_FLAG_META_HIDDEN))
-        (void)sql_set_dimension_option(&rd->metric_uuid, "hidden");
+    if (!rrddim_flag_check(rd, RRDDIM_FLAG_META_HIDDEN)) {
+        rrddim_flag_set(rd, RRDDIM_FLAG_META_HIDDEN);
+        metaqueue_dimension_update_flags(rd);
+    }
 
-    rrddim_flag_set(rd, RRDDIM_FLAG_HIDDEN);
-    rrddim_flag_set(rd, RRDDIM_FLAG_META_HIDDEN);
+    rrddim_option_set(rd, RRDDIM_OPTION_HIDDEN);
     rrdcontext_updated_rrddim_flags(rd);
     return 0;
 }
 
 int rrddim_unhide(RRDSET *st, const char *id) {
-    debug(D_RRD_CALLS, "rrddim_unhide() for chart %s, dimension %s", st->name, id);
+    debug(D_RRD_CALLS, "rrddim_unhide() for chart %s, dimension %s", rrdset_name(st), id);
 
     RRDHOST *host = st->rrdhost;
     RRDDIM *rd = rrddim_find(st, id);
     if(unlikely(!rd)) {
-        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, st->name, st->id, host->hostname);
+        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, rrdset_name(st), rrdset_id(st), rrdhost_hostname(host));
         return 1;
     }
-    if (rrddim_flag_check(rd, RRDDIM_FLAG_META_HIDDEN))
-        (void)sql_set_dimension_option(&rd->metric_uuid, NULL);
+    if (rrddim_flag_check(rd, RRDDIM_FLAG_META_HIDDEN)) {
+        rrddim_flag_clear(rd, RRDDIM_FLAG_META_HIDDEN);
+        metaqueue_dimension_update_flags(rd);
+    }
 
-    rrddim_flag_clear(rd, RRDDIM_FLAG_HIDDEN);
-    rrddim_flag_clear(rd, RRDDIM_FLAG_META_HIDDEN);
+    rrddim_option_clear(rd, RRDDIM_OPTION_HIDDEN);
     rrdcontext_updated_rrddim_flags(rd);
     return 0;
 }
 
 inline void rrddim_is_obsolete(RRDSET *st, RRDDIM *rd) {
-    debug(D_RRD_CALLS, "rrddim_is_obsolete() for chart %s, dimension %s", st->name, rd->name);
+    debug(D_RRD_CALLS, "rrddim_is_obsolete() for chart %s, dimension %s", rrdset_name(st), rrddim_name(rd));
 
     if(unlikely(rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED))) {
-        info("Cannot obsolete already archived dimension %s from chart %s", rd->name, st->name);
+        info("Cannot obsolete already archived dimension %s from chart %s", rrddim_name(rd), rrdset_name(st));
         return;
     }
     rrddim_flag_set(rd, RRDDIM_FLAG_OBSOLETE);
     rrdset_flag_set(st, RRDSET_FLAG_OBSOLETE_DIMENSIONS);
+    rrdhost_flag_set(st->rrdhost, RRDHOST_FLAG_PENDING_OBSOLETE_DIMENSIONS);
     rrdcontext_updated_rrddim_flags(rd);
 }
 
 inline void rrddim_isnot_obsolete(RRDSET *st __maybe_unused, RRDDIM *rd) {
-    debug(D_RRD_CALLS, "rrddim_isnot_obsolete() for chart %s, dimension %s", st->name, rd->name);
+    debug(D_RRD_CALLS, "rrddim_isnot_obsolete() for chart %s, dimension %s", rrdset_name(st), rrddim_name(rd));
 
     rrddim_flag_clear(rd, RRDDIM_FLAG_OBSOLETE);
     rrdcontext_updated_rrddim_flags(rd);
@@ -496,30 +549,34 @@ inline void rrddim_isnot_obsolete(RRDSET *st __maybe_unused, RRDDIM *rd) {
 // ----------------------------------------------------------------------------
 // RRDDIM - collect values for a dimension
 
-inline collected_number rrddim_set_by_pointer(RRDSET *st __maybe_unused, RRDDIM *rd, collected_number value) {
-    debug(D_RRD_CALLS, "rrddim_set_by_pointer() for chart %s, dimension %s, value " COLLECTED_NUMBER_FORMAT, st->name, rd->name, value);
+inline collected_number rrddim_set_by_pointer(RRDSET *st, RRDDIM *rd, collected_number value) {
+    struct timeval now;
+    now_realtime_timeval(&now);
+
+    return rrddim_timed_set_by_pointer(st, rd, now, value);
+}
 
-    rrdcontext_collected_rrddim(rd);
+collected_number rrddim_timed_set_by_pointer(RRDSET *st __maybe_unused, RRDDIM *rd, struct timeval collected_time, collected_number value) {
+    debug(D_RRD_CALLS, "rrddim_set_by_pointer() for chart %s, dimension %s, value " COLLECTED_NUMBER_FORMAT, rrdset_name(st), rrddim_name(rd), value);
 
-    now_realtime_timeval(&rd->last_collected_time);
+    rd->last_collected_time = collected_time;
     rd->collected_value = value;
     rd->updated = 1;
-
     rd->collections_counter++;
 
     collected_number v = (value >= 0) ? value : -value;
-    if(unlikely(v > rd->collected_value_max)) rd->collected_value_max = v;
-
-    // fprintf(stderr, "%s.%s %llu " COLLECTED_NUMBER_FORMAT " dt %0.6f" " rate " NETDATA_DOUBLE_FORMAT "\n", st->name, rd->name, st->usec_since_last_update, value, (float)((double)st->usec_since_last_update / (double)1000000), (NETDATA_DOUBLE)((value - rd->last_collected_value) * (NETDATA_DOUBLE)rd->multiplier / (NETDATA_DOUBLE)rd->divisor * 1000000.0 / (NETDATA_DOUBLE)st->usec_since_last_update));
+    if (unlikely(v > rd->collected_value_max))
+        rd->collected_value_max = v;
 
     return rd->last_collected_value;
 }
 
+
 collected_number rrddim_set(RRDSET *st, const char *id, collected_number value) {
     RRDHOST *host = st->rrdhost;
     RRDDIM *rd = rrddim_find(st, id);
     if(unlikely(!rd)) {
-        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, st->name, st->id, host->hostname);
+        error("Cannot find dimension with id '%s' on stats '%s' (%s) on host '%s'.", id, rrdset_name(st), rrdset_id(st), rrdhost_hostname(host));
         return 0;
     }
 
@@ -560,7 +617,7 @@ struct rrddim_map_save_v019 {
     long double last_calculated_value;              // ignored
     long double last_stored_value;                  // ignored
     long long collected_value;                      // ignored
-    long long last_collected_value;                 // ignored
+    long long last_collected_value;                 // load and save
     long double collected_volume;                   // ignored
     long double stored_volume;                      // ignored
     void *next;                                     // ignored
@@ -578,22 +635,23 @@ size_t rrddim_memory_file_header_size(void) {
 }
 
 void rrddim_memory_file_update(RRDDIM *rd) {
-    if(!rd->rd_on_file) return;
+    if(!rd || !rd->rd_on_file) return;
     struct rrddim_map_save_v019 *rd_on_file = rd->rd_on_file;
 
     rd_on_file->last_collected_time.tv_sec = rd->last_collected_time.tv_sec;
     rd_on_file->last_collected_time.tv_usec = rd->last_collected_time.tv_usec;
+    rd_on_file->last_collected_value = rd->last_collected_value;
 }
 
 void rrddim_memory_file_free(RRDDIM *rd) {
-    if(!rd->rd_on_file) return;
+    if(!rd || !rd->rd_on_file) return;
 
     // needed for memory mode map, to save the latest state
     rrddim_memory_file_update(rd);
 
     struct rrddim_map_save_v019 *rd_on_file = rd->rd_on_file;
     freez(rd_on_file->cache_filename);
-    munmap(rd_on_file, rd_on_file->memsize);
+    netdata_munmap(rd_on_file, rd_on_file->memsize);
 
     // remove the pointers from the RRDDIM
     rd->rd_on_file = NULL;
@@ -601,13 +659,13 @@ void rrddim_memory_file_free(RRDDIM *rd) {
 }
 
 const char *rrddim_cache_filename(RRDDIM *rd) {
-    if(!rd->rd_on_file) return NULL;
+    if(!rd || !rd->rd_on_file) return NULL;
     struct rrddim_map_save_v019 *rd_on_file = rd->rd_on_file;
     return rd_on_file->cache_filename;
 }
 
 void rrddim_memory_file_save(RRDDIM *rd) {
-    if(!rd->rd_on_file) return;
+    if(!rd || !rd->rd_on_file) return;
 
     rrddim_memory_file_update(rd);
 
@@ -627,7 +685,7 @@ bool rrddim_memory_load_or_create_map_save(RRDSET *st, RRDDIM *rd, RRD_MEMORY_MO
 
     char filename[FILENAME_MAX + 1];
     char fullfilename[FILENAME_MAX + 1];
-    rrdset_strncpyz_name(filename, rd->id, FILENAME_MAX);
+    rrdset_strncpyz_name(filename, rrddim_id(rd), FILENAME_MAX);
     snprintfz(fullfilename, FILENAME_MAX, "%s/%s.db", st->cache_dir, filename);
 
     rd_on_file = (struct rrddim_map_save_v019 *)netdata_mmap(fullfilename, size,
@@ -646,7 +704,7 @@ bool rrddim_memory_load_or_create_map_save(RRDSET *st, RRDDIM *rd, RRD_MEMORY_MO
         reset = 1;
     }
     else if(rd_on_file->memsize != size) {
-        error("File %s does not have the desired size, expected %lu but found %lu. Clearing it.", fullfilename, size, rd_on_file->memsize);
+        error("File %s does not have the desired size, expected %lu but found %lu. Clearing it.", fullfilename, size, (unsigned long int) rd_on_file->memsize);
         memset(rd_on_file, 0, size);
         reset = 1;
     }
@@ -662,6 +720,8 @@ bool rrddim_memory_load_or_create_map_save(RRDSET *st, RRDDIM *rd, RRD_MEMORY_MO
     }
 
     if(!reset) {
+        rd->last_collected_value = rd_on_file->last_collected_value;
+
         if(rd_on_file->algorithm != rd->algorithm)
             info("File %s does not have the expected algorithm (expected %u '%s', found %u '%s'). Previous values may be wrong.",
                  fullfilename, rd->algorithm, rrd_algorithm_name(rd->algorithm), rd_on_file->algorithm, rrd_algorithm_name(rd_on_file->algorithm));
diff --git a/database/rrddimvar.c b/database/rrddimvar.c
index 3c2ed75e5..449ceeb93 100644
--- a/database/rrddimvar.c
+++ b/database/rrddimvar.c
@@ -1,84 +1,87 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
-#define NETDATA_HEALTH_INTERNALS
 #include "rrd.h"
 
+typedef struct rrddimvar {
+    struct rrddim *rrddim;
+
+    STRING *prefix;
+    STRING *suffix;
+    void *value;
+
+    const RRDVAR_ACQUIRED *rrdvar_local_dim_id;
+    const RRDVAR_ACQUIRED *rrdvar_local_dim_name;
+
+    const RRDVAR_ACQUIRED *rrdvar_family_id;
+    const RRDVAR_ACQUIRED *rrdvar_family_name;
+    const RRDVAR_ACQUIRED *rrdvar_family_context_dim_id;
+    const RRDVAR_ACQUIRED *rrdvar_family_context_dim_name;
+
+    const RRDVAR_ACQUIRED *rrdvar_host_chart_id_dim_id;
+    const RRDVAR_ACQUIRED *rrdvar_host_chart_id_dim_name;
+    const RRDVAR_ACQUIRED *rrdvar_host_chart_name_dim_id;
+    const RRDVAR_ACQUIRED *rrdvar_host_chart_name_dim_name;
+
+    RRDVAR_FLAGS flags:24;
+    RRDVAR_TYPE type:8;
+} RRDDIMVAR;
+
 // ----------------------------------------------------------------------------
 // RRDDIMVAR management
 // DIMENSION VARIABLES
 
 #define RRDDIMVAR_ID_MAX 1024
 
-static inline void rrddimvar_free_variables(RRDDIMVAR *rs) {
+static inline void rrddimvar_free_variables_unsafe(RRDDIMVAR *rs) {
     RRDDIM *rd = rs->rrddim;
     RRDSET *st = rd->rrdset;
     RRDHOST *host = st->rrdhost;
 
     // CHART VARIABLES FOR THIS DIMENSION
 
-    rrdvar_free(host, &st->rrdvar_root_index, rs->var_local_id);
-    rs->var_local_id = NULL;
+    if(st->rrdvars) {
+        rrdvar_release_and_del(st->rrdvars, rs->rrdvar_local_dim_id);
+        rs->rrdvar_local_dim_id = NULL;
 
-    rrdvar_free(host, &st->rrdvar_root_index, rs->var_local_name);
-    rs->var_local_name = NULL;
+        rrdvar_release_and_del(st->rrdvars, rs->rrdvar_local_dim_name);
+        rs->rrdvar_local_dim_name = NULL;
+    }
 
     // FAMILY VARIABLES FOR THIS DIMENSION
 
-    rrdvar_free(host, &st->rrdfamily->rrdvar_root_index, rs->var_family_id);
-    rs->var_family_id = NULL;
+    if(st->rrdfamily) {
+        rrdvar_release_and_del(rrdfamily_rrdvars_dict(st->rrdfamily), rs->rrdvar_family_id);
+        rs->rrdvar_family_id = NULL;
 
-    rrdvar_free(host, &st->rrdfamily->rrdvar_root_index, rs->var_family_name);
-    rs->var_family_name = NULL;
+        rrdvar_release_and_del(rrdfamily_rrdvars_dict(st->rrdfamily), rs->rrdvar_family_name);
+        rs->rrdvar_family_name = NULL;
 
-    rrdvar_free(host, &st->rrdfamily->rrdvar_root_index, rs->var_family_contextid);
-    rs->var_family_contextid = NULL;
+        rrdvar_release_and_del(rrdfamily_rrdvars_dict(st->rrdfamily), rs->rrdvar_family_context_dim_id);
+        rs->rrdvar_family_context_dim_id = NULL;
 
-    rrdvar_free(host, &st->rrdfamily->rrdvar_root_index, rs->var_family_contextname);
-    rs->var_family_contextname = NULL;
+        rrdvar_release_and_del(rrdfamily_rrdvars_dict(st->rrdfamily), rs->rrdvar_family_context_dim_name);
+        rs->rrdvar_family_context_dim_name = NULL;
+    }
 
     // HOST VARIABLES FOR THIS DIMENSION
 
-    rrdvar_free(host, &host->rrdvar_root_index, rs->var_host_chartidid);
-    rs->var_host_chartidid = NULL;
-
-    rrdvar_free(host, &host->rrdvar_root_index, rs->var_host_chartidname);
-    rs->var_host_chartidname = NULL;
-
-    rrdvar_free(host, &host->rrdvar_root_index, rs->var_host_chartnameid);
-    rs->var_host_chartnameid = NULL;
-
-    rrdvar_free(host, &host->rrdvar_root_index, rs->var_host_chartnamename);
-    rs->var_host_chartnamename = NULL;
+    if(host->rrdvars && host->health_enabled) {
+        rrdvar_release_and_del(host->rrdvars, rs->rrdvar_host_chart_id_dim_id);
+        rs->rrdvar_host_chart_id_dim_id = NULL;
 
-    // KEYS
-
-    freez(rs->key_id);
-    rs->key_id = NULL;
-
-    freez(rs->key_name);
-    rs->key_name = NULL;
-
-    freez(rs->key_fullidid);
-    rs->key_fullidid = NULL;
-
-    freez(rs->key_fullidname);
-    rs->key_fullidname = NULL;
-
-    freez(rs->key_contextid);
-    rs->key_contextid = NULL;
+        rrdvar_release_and_del(host->rrdvars, rs->rrdvar_host_chart_id_dim_name);
+        rs->rrdvar_host_chart_id_dim_name = NULL;
 
-    freez(rs->key_contextname);
-    rs->key_contextname = NULL;
+        rrdvar_release_and_del(host->rrdvars, rs->rrdvar_host_chart_name_dim_id);
+        rs->rrdvar_host_chart_name_dim_id = NULL;
 
-    freez(rs->key_fullnameid);
-    rs->key_fullnameid = NULL;
-
-    freez(rs->key_fullnamename);
-    rs->key_fullnamename = NULL;
+        rrdvar_release_and_del(host->rrdvars, rs->rrdvar_host_chart_name_dim_name);
+        rs->rrdvar_host_chart_name_dim_name = NULL;
+    }
 }
 
-static inline void rrddimvar_create_variables(RRDDIMVAR *rs) {
-    rrddimvar_free_variables(rs);
+static inline void rrddimvar_update_variables_unsafe(RRDDIMVAR *rs) {
+    rrddimvar_free_variables_unsafe(rs);
 
     RRDDIM *rd = rs->rrddim;
     RRDSET *st = rd->rrdset;
@@ -88,29 +91,29 @@ static inline void rrddimvar_create_variables(RRDDIMVAR *rs) {
 
     // KEYS
 
-    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s%s%s", rs->prefix, rd->id, rs->suffix);
-    rs->key_id = strdupz(buffer);
+    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s%s%s", string2str(rs->prefix), rrddim_id(rd), string2str(rs->suffix));
+    STRING *key_dim_id = string_strdupz(buffer);
 
-    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s%s%s", rs->prefix, rd->name, rs->suffix);
-    rs->key_name = strdupz(buffer);
+    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s%s%s", string2str(rs->prefix), rrddim_name(rd), string2str(rs->suffix));
+    STRING *key_dim_name = string_strdupz(buffer);
 
-    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", st->id, rs->key_id);
-    rs->key_fullidid = strdupz(buffer);
+    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", rrdset_id(st), string2str(key_dim_id));
+    STRING *key_chart_id_dim_id = string_strdupz(buffer);
 
-    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", st->id, rs->key_name);
-    rs->key_fullidname = strdupz(buffer);
+    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", rrdset_id(st), string2str(key_dim_name));
+    STRING *key_chart_id_dim_name = string_strdupz(buffer);
 
-    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", st->context, rs->key_id);
-    rs->key_contextid = strdupz(buffer);
+    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", rrdset_context(st), string2str(key_dim_id));
+    STRING *key_context_dim_id = string_strdupz(buffer);
 
-    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", st->context, rs->key_name);
-    rs->key_contextname = strdupz(buffer);
+    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", rrdset_context(st), string2str(key_dim_name));
+    STRING *key_context_dim_name = string_strdupz(buffer);
 
-    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", st->name, rs->key_id);
-    rs->key_fullnameid = strdupz(buffer);
+    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", rrdset_name(st), string2str(key_dim_id));
+    STRING *key_chart_name_dim_id = string_strdupz(buffer);
 
-    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", st->name, rs->key_name);
-    rs->key_fullnamename = strdupz(buffer);
+    snprintfz(buffer, RRDDIMVAR_ID_MAX, "%s.%s", rrdset_name(st), string2str(key_dim_name));
+    STRING *key_chart_name_dim_name = string_strdupz(buffer);
 
     // CHART VARIABLES FOR THIS DIMENSION
     // -----------------------------------
@@ -119,8 +122,10 @@ static inline void rrddimvar_create_variables(RRDDIMVAR *rs) {
     // - $id
     // - $name
 
-    rs->var_local_id           = rrdvar_create_and_index("local", &st->rrdvar_root_index, rs->key_id, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
-    rs->var_local_name         = rrdvar_create_and_index("local", &st->rrdvar_root_index, rs->key_name, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
+    if(st->rrdvars) {
+        rs->rrdvar_local_dim_id = rrdvar_add_and_acquire("local", st->rrdvars, key_dim_id, rs->type, RRDVAR_FLAG_NONE, rs->value);
+        rs->rrdvar_local_dim_name = rrdvar_add_and_acquire("local", st->rrdvars, key_dim_name, rs->type, RRDVAR_FLAG_NONE, rs->value);
+    }
 
     // FAMILY VARIABLES FOR THIS DIMENSION
     // -----------------------------------
@@ -131,10 +136,12 @@ static inline void rrddimvar_create_variables(RRDDIMVAR *rs) {
     // - $chart-context.id
     // - $chart-context.name
 
-    rs->var_family_id          = rrdvar_create_and_index("family", &st->rrdfamily->rrdvar_root_index, rs->key_id, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
-    rs->var_family_name        = rrdvar_create_and_index("family", &st->rrdfamily->rrdvar_root_index, rs->key_name, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
-    rs->var_family_contextid   = rrdvar_create_and_index("family", &st->rrdfamily->rrdvar_root_index, rs->key_contextid, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
-    rs->var_family_contextname = rrdvar_create_and_index("family", &st->rrdfamily->rrdvar_root_index, rs->key_contextname, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
+    if(st->rrdfamily) {
+        rs->rrdvar_family_id = rrdvar_add_and_acquire("family", rrdfamily_rrdvars_dict(st->rrdfamily), key_dim_id, rs->type, RRDVAR_FLAG_NONE, rs->value);
+        rs->rrdvar_family_name = rrdvar_add_and_acquire("family", rrdfamily_rrdvars_dict(st->rrdfamily), key_dim_name, rs->type, RRDVAR_FLAG_NONE, rs->value);
+        rs->rrdvar_family_context_dim_id = rrdvar_add_and_acquire("family", rrdfamily_rrdvars_dict(st->rrdfamily), key_context_dim_id, rs->type, RRDVAR_FLAG_NONE, rs->value);
+        rs->rrdvar_family_context_dim_name = rrdvar_add_and_acquire("family", rrdfamily_rrdvars_dict(st->rrdfamily), key_context_dim_name, rs->type, RRDVAR_FLAG_NONE, rs->value);
+    }
 
     // HOST VARIABLES FOR THIS DIMENSION
     // -----------------------------------
@@ -145,73 +152,121 @@ static inline void rrddimvar_create_variables(RRDDIMVAR *rs) {
     // - $chart-name.id
     // - $chart-name.name
 
-    rs->var_host_chartidid      = rrdvar_create_and_index("host", &host->rrdvar_root_index, rs->key_fullidid, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
-    rs->var_host_chartidname    = rrdvar_create_and_index("host", &host->rrdvar_root_index, rs->key_fullidname, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
-    rs->var_host_chartnameid    = rrdvar_create_and_index("host", &host->rrdvar_root_index, rs->key_fullnameid, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
-    rs->var_host_chartnamename  = rrdvar_create_and_index("host", &host->rrdvar_root_index, rs->key_fullnamename, rs->type, RRDVAR_OPTION_DEFAULT, rs->value);
+    if(host->rrdvars && host->health_enabled) {
+        rs->rrdvar_host_chart_id_dim_id = rrdvar_add_and_acquire("host", host->rrdvars, key_chart_id_dim_id, rs->type, RRDVAR_FLAG_NONE, rs->value);
+        rs->rrdvar_host_chart_id_dim_name = rrdvar_add_and_acquire("host", host->rrdvars, key_chart_id_dim_name, rs->type, RRDVAR_FLAG_NONE, rs->value);
+        rs->rrdvar_host_chart_name_dim_id = rrdvar_add_and_acquire("host", host->rrdvars, key_chart_name_dim_id, rs->type, RRDVAR_FLAG_NONE, rs->value);
+        rs->rrdvar_host_chart_name_dim_name = rrdvar_add_and_acquire("host", host->rrdvars, key_chart_name_dim_name, rs->type, RRDVAR_FLAG_NONE, rs->value);
+    }
+
+    // free the keys
+
+    string_freez(key_dim_id);
+    string_freez(key_dim_name);
+    string_freez(key_chart_id_dim_id);
+    string_freez(key_chart_id_dim_name);
+    string_freez(key_context_dim_id);
+    string_freez(key_context_dim_name);
+    string_freez(key_chart_name_dim_id);
+    string_freez(key_chart_name_dim_name);
 }
 
-RRDDIMVAR *rrddimvar_create(RRDDIM *rd, RRDVAR_TYPE type, const char *prefix, const char *suffix, void *value, RRDVAR_OPTIONS options) {
-    RRDSET *st = rd->rrdset;
-    (void)st;
+struct rrddimvar_constructor {
+    RRDDIM *rrddim;
+    const char *prefix;
+    const char *suffix;
+    void *value;
+    RRDVAR_FLAGS flags :16;
+    RRDVAR_TYPE type:8;
+};
 
-    debug(D_VARIABLES, "RRDDIMSET create for chart id '%s' name '%s', dimension id '%s', name '%s%s%s'", st->id, st->name, rd->id, (prefix)?prefix:"", rd->name, (suffix)?suffix:"");
+static void rrddimvar_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddimvar, void *constructor_data) {
+    RRDDIMVAR *rs = rrddimvar;
+    struct rrddimvar_constructor *ctr = constructor_data;
 
-    if(!prefix) prefix = "";
-    if(!suffix) suffix = "";
+    if(!ctr->prefix) ctr->prefix = "";
+    if(!ctr->suffix) ctr->suffix = "";
+
+    rs->prefix = string_strdupz(ctr->prefix);
+    rs->suffix = string_strdupz(ctr->suffix);
+
+    rs->type = ctr->type;
+    rs->value = ctr->value;
+    rs->flags = ctr->flags;
+    rs->rrddim = ctr->rrddim;
+
+    rrddimvar_update_variables_unsafe(rs);
+}
+
+static bool rrddimvar_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddimvar, void *new_rrddimvar __maybe_unused, void *constructor_data __maybe_unused) {
+    RRDDIMVAR *rs = rrddimvar;
+    rrddimvar_update_variables_unsafe(rs);
+
+    return true;
+}
 
-    RRDDIMVAR *rs = (RRDDIMVAR *)callocz(1, sizeof(RRDDIMVAR));
+static void rrddimvar_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrddimvar, void *rrdset __maybe_unused) {
+    RRDDIMVAR *rs = rrddimvar;
+    rrddimvar_free_variables_unsafe(rs);
+    string_freez(rs->prefix);
+    string_freez(rs->suffix);
+}
 
-    rs->prefix = strdupz(prefix);
-    rs->suffix = strdupz(suffix);
+void rrddimvar_index_init(RRDSET *st) {
+    if(!st->rrddimvar_root_index) {
+        st->rrddimvar_root_index = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
 
-    rs->type = type;
-    rs->value = value;
-    rs->options = options;
-    rs->rrddim = rd;
+        dictionary_register_insert_callback(st->rrddimvar_root_index, rrddimvar_insert_callback, NULL);
+        dictionary_register_conflict_callback(st->rrddimvar_root_index, rrddimvar_conflict_callback, NULL);
+        dictionary_register_delete_callback(st->rrddimvar_root_index, rrddimvar_delete_callback, st);
+    }
+}
 
-    rs->next = rd->variables;
-    rd->variables = rs;
+void rrddimvar_index_destroy(RRDSET *st) {
+    dictionary_destroy(st->rrddimvar_root_index);
+    st->rrddimvar_root_index = NULL;
+}
 
-    rrddimvar_create_variables(rs);
+void rrddimvar_add_and_leave_released(RRDDIM *rd, RRDVAR_TYPE type, const char *prefix, const char *suffix, void *value, RRDVAR_FLAGS flags) {
+    if(!prefix) prefix = "";
+    if(!suffix) suffix = "";
 
-    return rs;
+    char key[RRDDIMVAR_ID_MAX + 1];
+    size_t key_len = snprintfz(key, RRDDIMVAR_ID_MAX, "%s_%s_%s", prefix, rrddim_id(rd), suffix);
+
+    struct rrddimvar_constructor tmp = {
+        .suffix = suffix,
+        .prefix = prefix,
+        .type = type,
+        .flags = flags,
+        .value = value,
+        .rrddim = rd
+    };
+    dictionary_set_advanced(rd->rrdset->rrddimvar_root_index, key, (ssize_t)(key_len + 1), NULL, sizeof(RRDDIMVAR), &tmp);
 }
 
 void rrddimvar_rename_all(RRDDIM *rd) {
     RRDSET *st = rd->rrdset;
-    (void)st;
 
-    debug(D_VARIABLES, "RRDDIMSET rename for chart id '%s' name '%s', dimension id '%s', name '%s'", st->id, st->name, rd->id, rd->name);
+    debug(D_VARIABLES, "RRDDIMVAR rename for chart id '%s' name '%s', dimension id '%s', name '%s'", rrdset_id(st), rrdset_name(st), rrddim_id(rd), rrddim_name(rd));
 
-    RRDDIMVAR *rs, *next = rd->variables;
-    while((rs = next)) {
-        next = rs->next;
-        rrddimvar_create_variables(rs);
+    RRDDIMVAR *rs;
+    dfe_start_write(st->rrddimvar_root_index, rs) {
+        if(unlikely(rs->rrddim == rd))
+            rrddimvar_update_variables_unsafe(rs);
     }
+    dfe_done(rs);
 }
 
-void rrddimvar_free(RRDDIMVAR *rs) {
-    RRDDIM *rd = rs->rrddim;
+void rrddimvar_delete_all(RRDDIM *rd) {
     RRDSET *st = rd->rrdset;
-    debug(D_VARIABLES, "RRDDIMSET free for chart id '%s' name '%s', dimension id '%s', name '%s', prefix='%s', suffix='%s'", st->id, st->name, rd->id, rd->name, rs->prefix, rs->suffix);
 
-    rrddimvar_free_variables(rs);
+    debug(D_VARIABLES, "RRDDIMVAR delete for chart id '%s' name '%s', dimension id '%s', name '%s'", rrdset_id(st), rrdset_name(st), rrddim_id(rd), rrddim_name(rd));
 
-    if(rd->variables == rs) {
-        debug(D_VARIABLES, "RRDDIMSET removing first entry for chart id '%s' name '%s', dimension id '%s', name '%s'", st->id, st->name, rd->id, rd->name);
-        rd->variables = rs->next;
-    }
-    else {
-        debug(D_VARIABLES, "RRDDIMSET removing non-first entry for chart id '%s' name '%s', dimension id '%s', name '%s'", st->id, st->name, rd->id, rd->name);
-        RRDDIMVAR *t;
-        for (t = rd->variables; t && t->next != rs; t = t->next) ;
-        if(!t) error("RRDDIMVAR '%s' not found in dimension '%s/%s' variables linked list", rs->key_name, st->id, rd->id);
-        else t->next = rs->next;
+    RRDDIMVAR *rs;
+    dfe_start_write(st->rrddimvar_root_index, rs) {
+        if(unlikely(rs->rrddim == rd))
+            dictionary_del(st->rrddimvar_root_index, rs_dfe.name);
     }
-
-    freez(rs->prefix);
-    freez(rs->suffix);
-    freez(rs);
+    dfe_done(rs);
 }
-
diff --git a/database/rrddimvar.h b/database/rrddimvar.h
index 3494824be..a803ea753 100644
--- a/database/rrddimvar.h
+++ b/database/rrddimvar.h
@@ -10,47 +10,12 @@
 // calculated / processed by the normal data collection process
 // This means, there will be no speed penalty for using
 // these variables
-struct rrddimvar {
-    char *prefix;
-    char *suffix;
-
-    char *key_id;                   // dimension id
-    char *key_name;                 // dimension name
-    char *key_contextid;            // context + dimension id
-    char *key_contextname;          // context + dimension name
-    char *key_fullidid;             // chart type.chart id + dimension id
-    char *key_fullidname;           // chart type.chart id + dimension name
-    char *key_fullnameid;           // chart type.chart name + dimension id
-    char *key_fullnamename;         // chart type.chart name + dimension name
-
-    RRDVAR_TYPE type;
-    void *value;
-
-    RRDVAR_OPTIONS options;
-
-    RRDVAR *var_local_id;
-    RRDVAR *var_local_name;
-
-    RRDVAR *var_family_id;
-    RRDVAR *var_family_name;
-    RRDVAR *var_family_contextid;
-    RRDVAR *var_family_contextname;
-
-    RRDVAR *var_host_chartidid;
-    RRDVAR *var_host_chartidname;
-    RRDVAR *var_host_chartnameid;
-    RRDVAR *var_host_chartnamename;
-
-    struct rrddim *rrddim;
-
-    struct rrddimvar *next;
-};
-
-
-extern void rrddimvar_rename_all(RRDDIM *rd);
-extern RRDDIMVAR *rrddimvar_create(RRDDIM *rd, RRDVAR_TYPE type, const char *prefix, const char *suffix, void *value, RRDVAR_OPTIONS options);
-extern void rrddimvar_free(RRDDIMVAR *rs);
 
+void rrddimvar_rename_all(RRDDIM *rd);
+void rrddimvar_add_and_leave_released(RRDDIM *rd, RRDVAR_TYPE type, const char *prefix, const char *suffix, void *value, RRDVAR_FLAGS flags);
+void rrddimvar_delete_all(RRDDIM *rd);
 
+void rrddimvar_index_init(RRDSET *st);
+void rrddimvar_index_destroy(RRDSET *st);
 
 #endif //NETDATA_RRDDIMVAR_H
diff --git a/database/rrdfamily.c b/database/rrdfamily.c
index 3d91c3788..e7d1536c8 100644
--- a/database/rrdfamily.c
+++ b/database/rrdfamily.c
@@ -3,59 +3,66 @@
 #define NETDATA_RRD_INTERNALS
 #include "rrd.h"
 
+typedef struct rrdfamily {
+    STRING *family;
+    DICTIONARY *rrdvars;
+} RRDFAMILY;
+
 // ----------------------------------------------------------------------------
 // RRDFAMILY index
 
-int rrdfamily_compare(void *a, void *b) {
-    if(((RRDFAMILY *)a)->hash_family < ((RRDFAMILY *)b)->hash_family) return -1;
-    else if(((RRDFAMILY *)a)->hash_family > ((RRDFAMILY *)b)->hash_family) return 1;
-    else return strcmp(((RRDFAMILY *)a)->family, ((RRDFAMILY *)b)->family);
-}
+struct rrdfamily_constructor {
+    const char *family;
+};
 
-#define rrdfamily_index_add(host, rc) (RRDFAMILY *)avl_insert_lock(&((host)->rrdfamily_root_index), (avl_t *)(rc))
-#define rrdfamily_index_del(host, rc) (RRDFAMILY *)avl_remove_lock(&((host)->rrdfamily_root_index), (avl_t *)(rc))
+static void rrdfamily_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdfamily, void *constructor_data) {
+    RRDFAMILY *rf = rrdfamily;
+    struct rrdfamily_constructor *ctr = constructor_data;
 
-static RRDFAMILY *rrdfamily_index_find(RRDHOST *host, const char *id, uint32_t hash) {
-    RRDFAMILY tmp;
-    tmp.family = id;
-    tmp.hash_family = (hash)?hash:simple_hash(tmp.family);
+    rf->family = string_strdupz(ctr->family);
+    rf->rrdvars = rrdvariables_create();
+}
 
-    return (RRDFAMILY *)avl_search_lock(&(host->rrdfamily_root_index), (avl_t *) &tmp);
+static void rrdfamily_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdfamily, void *rrdhost __maybe_unused) {
+    RRDFAMILY *rf = rrdfamily;
+    string_freez(rf->family);
+    rrdvariables_destroy(rf->rrdvars);
+    rf->family = NULL;
+    rf->rrdvars = NULL;
 }
 
-RRDFAMILY *rrdfamily_create(RRDHOST *host, const char *id) {
-    RRDFAMILY *rc = rrdfamily_index_find(host, id, 0);
-    if(!rc) {
-        rc = callocz(1, sizeof(RRDFAMILY));
+void rrdfamily_index_init(RRDHOST *host) {
+    if(!host->rrdfamily_root_index) {
+        host->rrdfamily_root_index = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
 
-        rc->family = strdupz(id);
-        rc->hash_family = simple_hash(rc->family);
+        dictionary_register_insert_callback(host->rrdfamily_root_index, rrdfamily_insert_callback, NULL);
+        dictionary_register_delete_callback(host->rrdfamily_root_index, rrdfamily_delete_callback, host);
+    }
+}
 
-        // initialize the variables index
-        avl_init_lock(&rc->rrdvar_root_index, rrdvar_compare);
+void rrdfamily_index_destroy(RRDHOST *host) {
+    dictionary_destroy(host->rrdfamily_root_index);
+    host->rrdfamily_root_index = NULL;
+}
 
-        RRDFAMILY *ret = rrdfamily_index_add(host, rc);
-        if(ret != rc)
-            error("RRDFAMILY: INTERNAL ERROR: Expected to INSERT RRDFAMILY '%s' into index, but inserted '%s'.", rc->family, (ret)?ret->family:"NONE");
-    }
 
-    rc->use_count++;
-    return rc;
+// ----------------------------------------------------------------------------
+// RRDFAMILY management
+
+const RRDFAMILY_ACQUIRED *rrdfamily_add_and_acquire(RRDHOST *host, const char *id) {
+    struct rrdfamily_constructor tmp = {
+        .family = id,
+    };
+    return (const RRDFAMILY_ACQUIRED *)dictionary_set_and_acquire_item_advanced(host->rrdfamily_root_index, id, -1, NULL, sizeof(RRDFAMILY), &tmp);
 }
 
-void rrdfamily_free(RRDHOST *host, RRDFAMILY *rc) {
-    rc->use_count--;
-    if(!rc->use_count) {
-        RRDFAMILY *ret = rrdfamily_index_del(host, rc);
-        if(ret != rc)
-            error("RRDFAMILY: INTERNAL ERROR: Expected to DELETE RRDFAMILY '%s' from index, but deleted '%s'.", rc->family, (ret)?ret->family:"NONE");
-        else {
-            debug(D_RRD_CALLS, "RRDFAMILY: Cleaning up remaining family variables for host '%s', family '%s'", host->hostname, rc->family);
-            rrdvar_free_remaining_variables(host, &rc->rrdvar_root_index);
-
-            freez((void *) rc->family);
-            freez(rc);
-        }
-    }
+void rrdfamily_release(RRDHOST *host, const RRDFAMILY_ACQUIRED *rfa) {
+    if(unlikely(!rfa)) return;
+    dictionary_acquired_item_release(host->rrdfamily_root_index, (const DICTIONARY_ITEM *)rfa);
 }
 
+DICTIONARY *rrdfamily_rrdvars_dict(const RRDFAMILY_ACQUIRED *rfa) {
+    if(unlikely(!rfa)) return NULL;
+    RRDFAMILY *rf = dictionary_acquired_item_value((const DICTIONARY_ITEM *)rfa);
+    return(rf->rrdvars);
+}
diff --git a/database/rrdfunctions.c b/database/rrdfunctions.c
new file mode 100644
index 000000000..fb847a356
--- /dev/null
+++ b/database/rrdfunctions.c
@@ -0,0 +1,758 @@
+#define NETDATA_RRD_INTERNALS
+#include "rrd.h"
+
+#define MAX_FUNCTION_LENGTH (PLUGINSD_LINE_MAX - 512) // we need some space for the rest of the line
+
+static unsigned char functions_allowed_chars[256] = {
+    [0] = '\0', //
+    [1] = '_', //
+    [2] = '_', //
+    [3] = '_', //
+    [4] = '_', //
+    [5] = '_', //
+    [6] = '_', //
+    [7] = '_', //
+    [8] = '_', //
+    [9] = ' ', // Horizontal Tab
+    [10] = ' ', // Line Feed
+    [11] = ' ', // Vertical Tab
+    [12] = ' ', // Form Feed
+    [13] = ' ', // Carriage Return
+    [14] = '_', //
+    [15] = '_', //
+    [16] = '_', //
+    [17] = '_', //
+    [18] = '_', //
+    [19] = '_', //
+    [20] = '_', //
+    [21] = '_', //
+    [22] = '_', //
+    [23] = '_', //
+    [24] = '_', //
+    [25] = '_', //
+    [26] = '_', //
+    [27] = '_', //
+    [28] = '_', //
+    [29] = '_', //
+    [30] = '_', //
+    [31] = '_', //
+    [32] = ' ', // SPACE keep
+    [33] = '_', // !
+    [34] = '_', // "
+    [35] = '_', // #
+    [36] = '_', // $
+    [37] = '_', // %
+    [38] = '_', // &
+    [39] = '_', // '
+    [40] = '_', // (
+    [41] = '_', // )
+    [42] = '_', // *
+    [43] = '_', // +
+    [44] = ',', // , keep
+    [45] = '-', // - keep
+    [46] = '.', // . keep
+    [47] = '/', // / keep
+    [48] = '0', // 0 keep
+    [49] = '1', // 1 keep
+    [50] = '2', // 2 keep
+    [51] = '3', // 3 keep
+    [52] = '4', // 4 keep
+    [53] = '5', // 5 keep
+    [54] = '6', // 6 keep
+    [55] = '7', // 7 keep
+    [56] = '8', // 8 keep
+    [57] = '9', // 9 keep
+    [58] = ':', // : keep
+    [59] = ':', // ; convert ; to :
+    [60] = '_', // <
+    [61] = ':', // = convert = to :
+    [62] = '_', // >
+    [63] = '_', // ?
+    [64] = '_', // @
+    [65] = 'A', // A keep
+    [66] = 'B', // B keep
+    [67] = 'C', // C keep
+    [68] = 'D', // D keep
+    [69] = 'E', // E keep
+    [70] = 'F', // F keep
+    [71] = 'G', // G keep
+    [72] = 'H', // H keep
+    [73] = 'I', // I keep
+    [74] = 'J', // J keep
+    [75] = 'K', // K keep
+    [76] = 'L', // L keep
+    [77] = 'M', // M keep
+    [78] = 'N', // N keep
+    [79] = 'O', // O keep
+    [80] = 'P', // P keep
+    [81] = 'Q', // Q keep
+    [82] = 'R', // R keep
+    [83] = 'S', // S keep
+    [84] = 'T', // T keep
+    [85] = 'U', // U keep
+    [86] = 'V', // V keep
+    [87] = 'W', // W keep
+    [88] = 'X', // X keep
+    [89] = 'Y', // Y keep
+    [90] = 'Z', // Z keep
+    [91] = '_', // [
+    [92] = '/', // backslash convert \ to /
+    [93] = '_', // ]
+    [94] = '_', // ^
+    [95] = '_', // _ keep
+    [96] = '_', // `
+    [97] = 'a', // a keep
+    [98] = 'b', // b keep
+    [99] = 'c', // c keep
+    [100] = 'd', // d keep
+    [101] = 'e', // e keep
+    [102] = 'f', // f keep
+    [103] = 'g', // g keep
+    [104] = 'h', // h keep
+    [105] = 'i', // i keep
+    [106] = 'j', // j keep
+    [107] = 'k', // k keep
+    [108] = 'l', // l keep
+    [109] = 'm', // m keep
+    [110] = 'n', // n keep
+    [111] = 'o', // o keep
+    [112] = 'p', // p keep
+    [113] = 'q', // q keep
+    [114] = 'r', // r keep
+    [115] = 's', // s keep
+    [116] = 't', // t keep
+    [117] = 'u', // u keep
+    [118] = 'v', // v keep
+    [119] = 'w', // w keep
+    [120] = 'x', // x keep
+    [121] = 'y', // y keep
+    [122] = 'z', // z keep
+    [123] = '_', // {
+    [124] = '_', // |
+    [125] = '_', // }
+    [126] = '_', // ~
+    [127] = '_', //
+    [128] = '_', //
+    [129] = '_', //
+    [130] = '_', //
+    [131] = '_', //
+    [132] = '_', //
+    [133] = '_', //
+    [134] = '_', //
+    [135] = '_', //
+    [136] = '_', //
+    [137] = '_', //
+    [138] = '_', //
+    [139] = '_', //
+    [140] = '_', //
+    [141] = '_', //
+    [142] = '_', //
+    [143] = '_', //
+    [144] = '_', //
+    [145] = '_', //
+    [146] = '_', //
+    [147] = '_', //
+    [148] = '_', //
+    [149] = '_', //
+    [150] = '_', //
+    [151] = '_', //
+    [152] = '_', //
+    [153] = '_', //
+    [154] = '_', //
+    [155] = '_', //
+    [156] = '_', //
+    [157] = '_', //
+    [158] = '_', //
+    [159] = '_', //
+    [160] = '_', //
+    [161] = '_', //
+    [162] = '_', //
+    [163] = '_', //
+    [164] = '_', //
+    [165] = '_', //
+    [166] = '_', //
+    [167] = '_', //
+    [168] = '_', //
+    [169] = '_', //
+    [170] = '_', //
+    [171] = '_', //
+    [172] = '_', //
+    [173] = '_', //
+    [174] = '_', //
+    [175] = '_', //
+    [176] = '_', //
+    [177] = '_', //
+    [178] = '_', //
+    [179] = '_', //
+    [180] = '_', //
+    [181] = '_', //
+    [182] = '_', //
+    [183] = '_', //
+    [184] = '_', //
+    [185] = '_', //
+    [186] = '_', //
+    [187] = '_', //
+    [188] = '_', //
+    [189] = '_', //
+    [190] = '_', //
+    [191] = '_', //
+    [192] = '_', //
+    [193] = '_', //
+    [194] = '_', //
+    [195] = '_', //
+    [196] = '_', //
+    [197] = '_', //
+    [198] = '_', //
+    [199] = '_', //
+    [200] = '_', //
+    [201] = '_', //
+    [202] = '_', //
+    [203] = '_', //
+    [204] = '_', //
+    [205] = '_', //
+    [206] = '_', //
+    [207] = '_', //
+    [208] = '_', //
+    [209] = '_', //
+    [210] = '_', //
+    [211] = '_', //
+    [212] = '_', //
+    [213] = '_', //
+    [214] = '_', //
+    [215] = '_', //
+    [216] = '_', //
+    [217] = '_', //
+    [218] = '_', //
+    [219] = '_', //
+    [220] = '_', //
+    [221] = '_', //
+    [222] = '_', //
+    [223] = '_', //
+    [224] = '_', //
+    [225] = '_', //
+    [226] = '_', //
+    [227] = '_', //
+    [228] = '_', //
+    [229] = '_', //
+    [230] = '_', //
+    [231] = '_', //
+    [232] = '_', //
+    [233] = '_', //
+    [234] = '_', //
+    [235] = '_', //
+    [236] = '_', //
+    [237] = '_', //
+    [238] = '_', //
+    [239] = '_', //
+    [240] = '_', //
+    [241] = '_', //
+    [242] = '_', //
+    [243] = '_', //
+    [244] = '_', //
+    [245] = '_', //
+    [246] = '_', //
+    [247] = '_', //
+    [248] = '_', //
+    [249] = '_', //
+    [250] = '_', //
+    [251] = '_', //
+    [252] = '_', //
+    [253] = '_', //
+    [254] = '_', //
+    [255] = '_'  //
+};
+
+static inline size_t sanitize_function_text(char *dst, const char *src, size_t dst_len) {
+    return text_sanitize((unsigned char *)dst, (const unsigned char *)src, dst_len,
+                         functions_allowed_chars, true, "", NULL);
+}
+
+// we keep a dictionary per RRDSET with these functions
+// the dictionary is created on demand (only when a function is added to an RRDSET)
+
+typedef enum {
+    RRD_FUNCTION_LOCAL  = (1 << 0),
+    RRD_FUNCTION_GLOBAL = (1 << 1),
+
+    // this is 8-bit
+} RRD_FUNCTION_OPTIONS;
+
+struct rrd_collector_function {
+    bool sync;                      // when true, the function is called synchronously
+    uint8_t options;                // RRD_FUNCTION_OPTIONS
+    STRING *help;
+    int timeout;                    // the default timeout of the function
+
+    int (*function)(BUFFER *wb, int timeout, const char *function, void *collector_data,
+                    function_data_ready_callback callback, void *callback_data);
+
+    void *collector_data;
+    struct rrd_collector *collector;
+};
+
+// Each function points to this collector structure
+// so that when the collector exits, all of them will
+// be invalidated (running == false)
+// The last function that is using this collector
+// frees the structure too (or when the collector calls
+// rrdset_collector_finished()).
+
+struct rrd_collector {
+    int32_t refcount;
+    pid_t tid;
+    bool running;
+};
+
+// Each thread that adds RRDSET functions, has to call
+// rrdset_collector_started() and rrdset_collector_finished()
+// to create the collector structure.
+
+static __thread struct rrd_collector *thread_rrd_collector = NULL;
+
+static void rrd_collector_free(struct rrd_collector *rdc) {
+    int32_t expected = 0;
+    if(likely(!__atomic_compare_exchange_n(&rdc->refcount, &expected, -1, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))) {
+        // the collector is still referenced by charts.
+        // leave it hanging there, the last chart will actually free it.
+        return;
+    }
+
+    // we can free it now
+    freez(rdc);
+}
+
+// called once per collector
+void rrd_collector_started(void) {
+    if(likely(thread_rrd_collector)) return;
+
+    thread_rrd_collector = callocz(1, sizeof(struct rrd_collector));
+    thread_rrd_collector->tid = gettid();
+    thread_rrd_collector->running = true;
+}
+
+// called once per collector
+void rrd_collector_finished(void) {
+    if(!thread_rrd_collector)
+        return;
+
+    thread_rrd_collector->running = false;
+    rrd_collector_free(thread_rrd_collector);
+    thread_rrd_collector = NULL;
+}
+
+static struct rrd_collector *rrd_collector_acquire(void) {
+    __atomic_add_fetch(&thread_rrd_collector->refcount, 1, __ATOMIC_SEQ_CST);
+    return thread_rrd_collector;
+}
+
+static void rrd_collector_release(struct rrd_collector *rdc) {
+    if(unlikely(!rdc)) return;
+
+    int32_t refcount = __atomic_sub_fetch(&rdc->refcount, 1, __ATOMIC_SEQ_CST);
+    if(refcount == 0 && !rdc->running)
+        rrd_collector_free(rdc);
+}
+
+static void rrd_functions_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *func __maybe_unused,
+                                          void *rrdhost __maybe_unused) {
+    struct rrd_collector_function *rdcf = func;
+
+    if(!thread_rrd_collector)
+        fatal("RRDSET_COLLECTOR: called %s() for function '%s' without calling rrd_collector_started() first.",
+              __FUNCTION__, dictionary_acquired_item_name(item));
+
+    rdcf->collector = rrd_collector_acquire();
+}
+
+static void rrd_functions_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *func __maybe_unused,
+                                          void *rrdhost __maybe_unused) {
+    struct rrd_collector_function *rdcf = func;
+    rrd_collector_release(rdcf->collector);
+}
+
+static bool rrd_functions_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *func __maybe_unused,
+                                            void *new_func __maybe_unused, void *rrdhost __maybe_unused) {
+    struct rrd_collector_function *rdcf = func;
+    struct rrd_collector_function *new_rdcf = new_func;
+
+    if(!thread_rrd_collector)
+        fatal("RRDSET_COLLECTOR: called %s() for function '%s' without calling rrd_collector_started() first.",
+              __FUNCTION__, dictionary_acquired_item_name(item));
+
+    bool changed = false;
+
+    if(rdcf->collector != thread_rrd_collector) {
+        struct rrd_collector *old_rdc = rdcf->collector;
+        rdcf->collector = rrd_collector_acquire();
+        rrd_collector_release(old_rdc);
+        changed = true;
+    }
+
+    if(rdcf->function != new_rdcf->function) {
+        rdcf->function = new_rdcf->function;
+        changed = true;
+    }
+
+    if(rdcf->help != new_rdcf->help) {
+        STRING *old = rdcf->help;
+        rdcf->help = new_rdcf->help;
+        string_freez(old);
+        changed = true;
+    }
+    else
+        string_freez(new_rdcf->help);
+
+    if(rdcf->timeout != new_rdcf->timeout) {
+        rdcf->timeout = new_rdcf->timeout;
+        changed = true;
+    }
+
+    if(rdcf->sync != new_rdcf->sync) {
+        rdcf->sync = new_rdcf->sync;
+        changed = true;
+    }
+
+    if(rdcf->collector_data != new_rdcf->collector_data) {
+        rdcf->collector_data = new_rdcf->collector_data;
+        changed = true;
+    }
+
+    return changed;
+}
+
+
+void rrdfunctions_init(RRDHOST *host) {
+    if(host->functions) return;
+
+    host->functions = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
+    dictionary_register_insert_callback(host->functions, rrd_functions_insert_callback, host);
+    dictionary_register_delete_callback(host->functions, rrd_functions_delete_callback, host);
+    dictionary_register_conflict_callback(host->functions, rrd_functions_conflict_callback, host);
+}
+
+void rrdfunctions_destroy(RRDHOST *host) {
+    dictionary_destroy(host->functions);
+}
+
+void rrd_collector_add_function(RRDHOST *host, RRDSET *st, const char *name, int timeout, const char *help,
+                                bool sync, function_execute_at_collector function, void *collector_data) {
+
+    // RRDSET *st may be NULL in this function
+    // to create a GLOBAL function
+
+    if(st && !st->functions_view)
+        st->functions_view = dictionary_create_view(host->functions);
+
+    char key[PLUGINSD_LINE_MAX + 1];
+    sanitize_function_text(key, name, PLUGINSD_LINE_MAX);
+
+    struct rrd_collector_function tmp = {
+        .sync = sync,
+        .timeout = timeout,
+        .options = (st)?RRD_FUNCTION_LOCAL:RRD_FUNCTION_GLOBAL,
+        .function = function,
+        .collector_data = collector_data,
+        .help = string_strdupz(help),
+    };
+    const DICTIONARY_ITEM *item = dictionary_set_and_acquire_item(host->functions, key, &tmp, sizeof(tmp));
+
+    if(st)
+        dictionary_view_set(st->functions_view, key, item);
+
+    dictionary_acquired_item_release(host->functions, item);
+}
+
+void rrd_functions_expose_rrdpush(RRDSET *st, BUFFER *wb) {
+    if(!st->functions_view)
+        return;
+
+    struct rrd_collector_function *tmp;
+    dfe_start_read(st->functions_view, tmp) {
+        buffer_sprintf(wb
+                       , PLUGINSD_KEYWORD_FUNCTION " \"%s\" %d \"%s\"\n"
+                       , tmp_dfe.name
+                       , tmp->timeout
+                       , string2str(tmp->help)
+                       );
+    }
+    dfe_done(tmp);
+}
+
+struct rrd_function_call_wait {
+    bool free_with_signal;
+    bool data_are_ready;
+    netdata_mutex_t mutex;
+    pthread_cond_t cond;
+    int code;
+};
+
+static void rrd_function_call_wait_free(struct rrd_function_call_wait *tmp) {
+    pthread_cond_destroy(&tmp->cond);
+    netdata_mutex_destroy(&tmp->mutex);
+    freez(tmp);
+}
+
+struct {
+    const char *format;
+    uint8_t content_type;
+} function_formats[] = {
+    { .format = "application/json", CT_APPLICATION_JSON },
+    { .format = "text/plain",       CT_TEXT_PLAIN },
+    { .format = "application/xml",  CT_APPLICATION_XML },
+    { .format = "prometheus",       CT_PROMETHEUS },
+    { .format = "text",             CT_TEXT_PLAIN },
+    { .format = "txt",              CT_TEXT_PLAIN },
+    { .format = "json",             CT_APPLICATION_JSON },
+    { .format = "html",             CT_TEXT_HTML },
+    { .format = "text/html",        CT_TEXT_HTML },
+    { .format = "xml",              CT_APPLICATION_XML },
+
+    // terminator
+    { .format = NULL,               CT_TEXT_PLAIN },
+};
+
+uint8_t functions_format_to_content_type(const char *format) {
+    if(format && *format) {
+        for (int i = 0; function_formats[i].format; i++)
+            if (strcmp(function_formats[i].format, format) == 0)
+                return function_formats[i].content_type;
+    }
+
+    return CT_TEXT_PLAIN;
+}
+
+const char *functions_content_type_to_format(uint8_t content_type) {
+    for (int i = 0; function_formats[i].format; i++)
+        if (function_formats[i].content_type == content_type)
+            return function_formats[i].format;
+
+    return "text/plain";
+}
+
+int rrd_call_function_error(BUFFER *wb, const char *msg, int code) {
+    char buffer[PLUGINSD_LINE_MAX];
+    json_escape_string(buffer, msg, PLUGINSD_LINE_MAX);
+
+    buffer_flush(wb);
+    buffer_sprintf(wb, "{\"status\":%d,\"error_message\":\"%s\"}", code, buffer);
+    wb->contenttype = CT_APPLICATION_JSON;
+    buffer_no_cacheable(wb);
+    return code;
+}
+
+static int rrd_call_function_find(RRDHOST *host, BUFFER *wb, const char *name, size_t key_length, struct rrd_collector_function **rdcf) {
+    char buffer[MAX_FUNCTION_LENGTH + 1];
+
+    strncpyz(buffer, name, MAX_FUNCTION_LENGTH);
+    char *s = NULL;
+
+    *rdcf = NULL;
+    while(!(*rdcf) && buffer[0]) {
+        *rdcf = dictionary_get(host->functions, buffer);
+        if(*rdcf) break;
+
+        // if s == NULL, set it to the end of the buffer
+        // this should happen only the first time
+        if(unlikely(!s))
+            s = &buffer[key_length - 1];
+
+        // skip a word from the end
+        while(s >= buffer && !isspace(*s)) *s-- = '\0';
+
+        // skip all spaces
+        while(s >= buffer && isspace(*s)) *s-- = '\0';
+    }
+
+    buffer_flush(wb);
+
+    if(!(*rdcf))
+        return rrd_call_function_error(wb, "No collector is supplying this function on this host at this time.", HTTP_RESP_NOT_FOUND);
+
+    if(!(*rdcf)->collector->running)
+        return rrd_call_function_error(wb, "The collector that registered this function, is not currently running.", HTTP_RESP_BACKEND_FETCH_FAILED);
+
+    return HTTP_RESP_OK;
+}
+
+static void rrd_call_function_signal_when_ready(BUFFER *temp_wb __maybe_unused, int code, void *callback_data) {
+    struct rrd_function_call_wait *tmp = callback_data;
+    bool we_should_free = false;
+
+    netdata_mutex_lock(&tmp->mutex);
+
+    // since we got the mutex,
+    // the waiting thread is either in pthread_cond_timedwait()
+    // or gave up and left.
+
+    tmp->code = code;
+    tmp->data_are_ready = true;
+
+    if(tmp->free_with_signal)
+        we_should_free = true;
+
+    pthread_cond_signal(&tmp->cond);
+
+    netdata_mutex_unlock(&tmp->mutex);
+
+    if(we_should_free) {
+        buffer_free(temp_wb);
+        rrd_function_call_wait_free(tmp);
+    }
+}
+
+int rrd_call_function_and_wait(RRDHOST *host, BUFFER *wb, int timeout, const char *name) {
+    int code;
+
+    struct rrd_collector_function *rdcf = NULL;
+
+    char key[PLUGINSD_LINE_MAX + 1];
+    size_t key_length = sanitize_function_text(key, name, PLUGINSD_LINE_MAX);
+    code = rrd_call_function_find(host, wb, key, key_length, &rdcf);
+    if(code != HTTP_RESP_OK)
+        return code;
+
+    if(timeout <= 0)
+        timeout = rdcf->timeout;
+
+    struct timespec tp;
+    clock_gettime(CLOCK_REALTIME, &tp);
+    tp.tv_sec += (time_t)timeout;
+
+    if(rdcf->sync) {
+        code = rdcf->function(wb, timeout, key, rdcf->collector_data, NULL, NULL);
+    }
+    else {
+        struct rrd_function_call_wait *tmp = mallocz(sizeof(struct rrd_function_call_wait));
+        tmp->free_with_signal = false;
+        tmp->data_are_ready = false;
+        netdata_mutex_init(&tmp->mutex);
+        pthread_cond_init(&tmp->cond, NULL);
+
+        bool we_should_free = true;
+        BUFFER *temp_wb  = buffer_create(PLUGINSD_LINE_MAX + 1); // we need it because we may give up on it
+        temp_wb->contenttype = wb->contenttype;
+        code = rdcf->function(temp_wb, timeout, key, rdcf->collector_data, rrd_call_function_signal_when_ready, tmp);
+        if (code == HTTP_RESP_OK) {
+            netdata_mutex_lock(&tmp->mutex);
+
+            int rc = 0;
+            while (rc == 0 && !tmp->data_are_ready) {
+                // the mutex is unlocked within pthread_cond_timedwait()
+                rc = pthread_cond_timedwait(&tmp->cond, &tmp->mutex, &tp);
+                // the mutex is again ours
+            }
+
+            if (tmp->data_are_ready) {
+                // we have a response
+                buffer_fast_strcat(wb, buffer_tostring(temp_wb), buffer_strlen(temp_wb));
+                wb->contenttype = temp_wb->contenttype;
+                wb->expires = temp_wb->expires;
+
+                if(wb->expires)
+                    buffer_cacheable(wb);
+                else
+                    buffer_no_cacheable(wb);
+
+                code = tmp->code;
+            }
+            else if (rc == ETIMEDOUT) {
+                // timeout
+                // we will go away and let the callback free the structure
+                tmp->free_with_signal = true;
+                we_should_free = false;
+                code = rrd_call_function_error(wb, "Timeout while waiting for a response from the collector.", HTTP_RESP_GATEWAY_TIMEOUT);
+            }
+            else
+                code = rrd_call_function_error(wb, "Failed to get the response from the collector.", HTTP_RESP_INTERNAL_SERVER_ERROR);
+
+            netdata_mutex_unlock(&tmp->mutex);
+        }
+        else {
+            buffer_free(temp_wb);
+            if(!buffer_strlen(wb))
+                rrd_call_function_error(wb, "Failed to send request to the collector.", code);
+        }
+
+        if (we_should_free)
+            rrd_function_call_wait_free(tmp);
+    }
+
+    return code;
+}
+
+int rrd_call_function_async(RRDHOST *host, BUFFER *wb, int timeout, const char *name,
+    rrd_call_function_async_callback callback, void *callback_data) {
+    int code;
+
+    struct rrd_collector_function *rdcf = NULL;
+    char key[PLUGINSD_LINE_MAX + 1];
+    size_t key_length = sanitize_function_text(key, name, PLUGINSD_LINE_MAX);
+    code = rrd_call_function_find(host, wb, key, key_length, &rdcf);
+    if(code != HTTP_RESP_OK)
+        return code;
+
+    if(timeout <= 0)
+        timeout = rdcf->timeout;
+
+    code = rdcf->function(wb, timeout, key, rdcf->collector_data, callback, callback_data);
+
+    if(code != HTTP_RESP_OK) {
+        if (!buffer_strlen(wb))
+            rrd_call_function_error(wb, "Failed to send request to the collector.", code);
+    }
+
+    return code;
+}
+
+static void functions2json(DICTIONARY *functions, BUFFER *wb, const char *ident, const char *kq, const char *sq) {
+    struct rrd_collector_function *t;
+    dfe_start_read(functions, t) {
+        if(!t->collector->running) continue;
+
+        if(t_dfe.counter)
+            buffer_strcat(wb, ",\n");
+
+        buffer_sprintf(wb, "%s%s%s%s: {", ident, kq, t_dfe.name, kq);
+        buffer_sprintf(wb, "\n\t%s%shelp%s: %s%s%s", ident, kq, kq, sq, string2str(t->help), sq);
+        buffer_sprintf(wb, ",\n\t%s%stimeout%s: %d", ident, kq, kq, t->timeout);
+        buffer_sprintf(wb, ",\n\t%s%soptions%s: \"%s%s\"", ident, kq, kq
+                       , (t->options & RRD_FUNCTION_LOCAL)?"LOCAL ":""
+                       , (t->options & RRD_FUNCTION_GLOBAL)?"GLOBAL ":""
+                       );
+        buffer_sprintf(wb, "\n%s}", ident);
+    }
+    dfe_done(t);
+    buffer_strcat(wb, "\n");
+}
+
+void chart_functions2json(RRDSET *st, BUFFER *wb, int tabs, const char *kq, const char *sq) {
+    if(!st || !st->functions_view) return;
+
+    char ident[tabs + 1];
+    ident[tabs] = '\0';
+    while(tabs) ident[--tabs] = '\t';
+
+    functions2json(st->functions_view, wb, ident, kq, sq);
+}
+
+void host_functions2json(RRDHOST *host, BUFFER *wb, int tabs, const char *kq, const char *sq) {
+    if(!host || !host->functions) return;
+
+    char ident[tabs + 1];
+    ident[tabs] = '\0';
+    while(tabs) ident[--tabs] = '\t';
+
+    functions2json(host->functions, wb, ident, kq, sq);
+}
+
+void chart_functions_to_dict(DICTIONARY *rrdset_functions_view, DICTIONARY *dst) {
+    if(!rrdset_functions_view || !dst) return;
+
+    struct rrd_collector_function *t;
+    dfe_start_read(rrdset_functions_view, t) {
+        if(!t->collector->running) continue;
+
+        dictionary_set(dst, t_dfe.name, NULL, 0);
+    }
+    dfe_done(t);
+}
diff --git a/database/rrdfunctions.h b/database/rrdfunctions.h
new file mode 100644
index 000000000..f031ec34d
--- /dev/null
+++ b/database/rrdfunctions.h
@@ -0,0 +1,35 @@
+#ifndef NETDATA_RRDFUNCTIONS_H
+#define NETDATA_RRDFUNCTIONS_H 1
+
+#include "rrd.h"
+
+void rrdfunctions_init(RRDHOST *host);
+void rrdfunctions_destroy(RRDHOST *host);
+
+void rrd_collector_started(void);
+void rrd_collector_finished(void);
+
+typedef void (*function_data_ready_callback)(BUFFER *wb, int code, void *callback_data);
+
+typedef int (*function_execute_at_collector)(BUFFER *wb, int timeout, const char *function, void *collector_data,
+                                             function_data_ready_callback callback, void *callback_data);
+
+void rrd_collector_add_function(RRDHOST *host, RRDSET *st, const char *name, int timeout, const char *help,
+                                       bool sync, function_execute_at_collector function, void *collector_data);
+
+int rrd_call_function_and_wait(RRDHOST *host, BUFFER *wb, int timeout, const char *name);
+
+typedef void (*rrd_call_function_async_callback)(BUFFER *wb, int code, void *callback_data);
+int rrd_call_function_async(RRDHOST *host, BUFFER *wb, int timeout, const char *name, rrd_call_function_async_callback, void *callback_data);
+
+void rrd_functions_expose_rrdpush(RRDSET *st, BUFFER *wb);
+
+void chart_functions2json(RRDSET *st, BUFFER *wb, int tabs, const char *kq, const char *sq);
+void chart_functions_to_dict(DICTIONARY *rrdset_functions_view, DICTIONARY *dst);
+void host_functions2json(RRDHOST *host, BUFFER *wb, int tabs, const char *kq, const char *sq);
+
+uint8_t functions_format_to_content_type(const char *format);
+const char *functions_content_type_to_format(uint8_t content_type);
+int rrd_call_function_error(BUFFER *wb, const char *msg, int code);
+
+#endif // NETDATA_RRDFUNCTIONS_H
diff --git a/database/rrdhost.c b/database/rrdhost.c
index 7f4bd95ba..5ba13d47b 100644
--- a/database/rrdhost.c
+++ b/database/rrdhost.c
@@ -3,21 +3,21 @@
 #define NETDATA_RRD_INTERNALS
 #include "rrd.h"
 
-int storage_tiers = 1;
-int storage_tiers_grouping_iterations[RRD_STORAGE_TIERS] = { 1, 60, 60, 60, 60 };
+bool dbengine_enabled = false; // will become true if and when dbengine is initialized
+size_t storage_tiers = 3;
+size_t storage_tiers_grouping_iterations[RRD_STORAGE_TIERS] = { 1, 60, 60, 60, 60 };
 RRD_BACKFILL storage_tiers_backfill[RRD_STORAGE_TIERS] = { RRD_BACKFILL_NEW, RRD_BACKFILL_NEW, RRD_BACKFILL_NEW, RRD_BACKFILL_NEW, RRD_BACKFILL_NEW };
 
 #if RRD_STORAGE_TIERS != 5
 #error RRD_STORAGE_TIERS is not 5 - you need to update the grouping iterations per tier
 #endif
 
-int get_tier_grouping(int tier) {
+size_t get_tier_grouping(size_t tier) {
     if(unlikely(tier >= storage_tiers)) tier = storage_tiers - 1;
-    if(unlikely(tier < 0)) tier = 0;
 
-    int grouping = 1;
+    size_t grouping = 1;
     // first tier is always 1 iteration of whatever update every the chart has
-    for(int i = 1; i <= tier ;i++)
+    for(size_t i = 1; i <= tier ;i++)
         grouping *= storage_tiers_grouping_iterations[i];
 
     return grouping;
@@ -32,7 +32,7 @@ time_t rrdhost_free_orphan_time = 3600;
 
 bool is_storage_engine_shared(STORAGE_INSTANCE *engine) {
 #ifdef ENABLE_DBENGINE
-    for(int tier = 0; tier < storage_tiers ;tier++) {
+    for(size_t tier = 0; tier < storage_tiers ;tier++) {
         if (engine == (STORAGE_INSTANCE *)multidb_ctx[tier])
             return true;
     }
@@ -43,107 +43,144 @@ bool is_storage_engine_shared(STORAGE_INSTANCE *engine) {
 
 
 // ----------------------------------------------------------------------------
-// RRDHOST index
+// RRDHOST indexes management
 
-int rrdhost_compare(void* a, void* b) {
-    if(((RRDHOST *)a)->hash_machine_guid < ((RRDHOST *)b)->hash_machine_guid) return -1;
-    else if(((RRDHOST *)a)->hash_machine_guid > ((RRDHOST *)b)->hash_machine_guid) return 1;
-    else return strcmp(((RRDHOST *)a)->machine_guid, ((RRDHOST *)b)->machine_guid);
+DICTIONARY *rrdhost_root_index = NULL;
+static DICTIONARY *rrdhost_root_index_hostname = NULL;
+
+static inline void rrdhost_init() {
+    if(unlikely(!rrdhost_root_index)) {
+        rrdhost_root_index = dictionary_create(
+            DICT_OPTION_NAME_LINK_DONT_CLONE | DICT_OPTION_VALUE_LINK_DONT_CLONE | DICT_OPTION_DONT_OVERWRITE_VALUE);
+    }
+
+    if(unlikely(!rrdhost_root_index_hostname)) {
+        rrdhost_root_index_hostname = dictionary_create(
+            DICT_OPTION_NAME_LINK_DONT_CLONE | DICT_OPTION_VALUE_LINK_DONT_CLONE | DICT_OPTION_DONT_OVERWRITE_VALUE);
+    }
 }
 
-avl_tree_lock rrdhost_root_index = {
-        .avl_tree = { NULL, rrdhost_compare },
-        .rwlock = AVL_LOCK_INITIALIZER
-};
+// ----------------------------------------------------------------------------
+// RRDHOST index by UUID
+
+inline long rrdhost_hosts_available(void) {
+    return dictionary_entries(rrdhost_root_index);
+}
 
-RRDHOST *rrdhost_find_by_guid(const char *guid, uint32_t hash) {
-    debug(D_RRDHOST, "Searching in index for host with guid '%s'", guid);
+inline RRDHOST *rrdhost_find_by_guid(const char *guid) {
+    return dictionary_get(rrdhost_root_index, guid);
+}
 
-    RRDHOST tmp;
-    strncpyz(tmp.machine_guid, guid, GUID_LEN);
-    tmp.hash_machine_guid = (hash)?hash:simple_hash(tmp.machine_guid);
+static inline RRDHOST *rrdhost_index_add_by_guid(RRDHOST *host) {
+    RRDHOST *ret_machine_guid = dictionary_set(rrdhost_root_index, host->machine_guid, host, sizeof(RRDHOST));
+    if(ret_machine_guid == host)
+        rrdhost_option_set(host, RRDHOST_OPTION_INDEXED_MACHINE_GUID);
+    else {
+        rrdhost_option_clear(host, RRDHOST_OPTION_INDEXED_MACHINE_GUID);
+        error("RRDHOST: %s() host with machine guid '%s' is already indexed", __FUNCTION__, host->machine_guid);
+    }
 
-    return (RRDHOST *)avl_search_lock(&(rrdhost_root_index), (avl_t *) &tmp);
+    return host;
+}
+
+static void rrdhost_index_del_by_guid(RRDHOST *host) {
+    if(rrdhost_option_check(host, RRDHOST_OPTION_INDEXED_MACHINE_GUID)) {
+        if(!dictionary_del(rrdhost_root_index, host->machine_guid))
+            error("RRDHOST: %s() failed to delete machine guid '%s' from index", __FUNCTION__, host->machine_guid);
+
+        rrdhost_option_clear(host, RRDHOST_OPTION_INDEXED_MACHINE_GUID);
+    }
 }
 
-RRDHOST *rrdhost_find_by_hostname(const char *hostname, uint32_t hash) {
+// ----------------------------------------------------------------------------
+// RRDHOST index by hostname
+
+inline RRDHOST *rrdhost_find_by_hostname(const char *hostname) {
     if(unlikely(!strcmp(hostname, "localhost")))
         return localhost;
 
-    if(unlikely(!hash)) hash = simple_hash(hostname);
+    return dictionary_get(rrdhost_root_index_hostname, hostname);
+}
 
-    rrd_rdlock();
-    RRDHOST *host;
-    rrdhost_foreach_read(host) {
-        if(unlikely((hash == host->hash_hostname && !strcmp(hostname, host->hostname)))) {
-            rrd_unlock();
-            return host;
-        }
+static inline RRDHOST *rrdhost_index_add_hostname(RRDHOST *host) {
+    if(!host->hostname) return host;
+
+    RRDHOST *ret_hostname = dictionary_set(rrdhost_root_index_hostname, rrdhost_hostname(host), host, sizeof(RRDHOST));
+    if(ret_hostname == host)
+        rrdhost_option_set(host, RRDHOST_OPTION_INDEXED_HOSTNAME);
+    else {
+        rrdhost_option_clear(host, RRDHOST_OPTION_INDEXED_HOSTNAME);
+        error("RRDHOST: %s() host with hostname '%s' is already indexed", __FUNCTION__, rrdhost_hostname(host));
     }
-    rrd_unlock();
 
-    return NULL;
+    return host;
 }
 
-#define rrdhost_index_add(rrdhost) (RRDHOST *)avl_insert_lock(&(rrdhost_root_index), (avl_t *)(rrdhost))
-#define rrdhost_index_del(rrdhost) (RRDHOST *)avl_remove_lock(&(rrdhost_root_index), (avl_t *)(rrdhost))
+static inline void rrdhost_index_del_hostname(RRDHOST *host) {
+    if(unlikely(!host->hostname)) return;
+
+    if(rrdhost_option_check(host, RRDHOST_OPTION_INDEXED_HOSTNAME)) {
+        if(!dictionary_del(rrdhost_root_index_hostname, rrdhost_hostname(host)))
+            error("RRDHOST: %s() failed to delete hostname '%s' from index", __FUNCTION__, rrdhost_hostname(host));
 
+        rrdhost_option_clear(host, RRDHOST_OPTION_INDEXED_HOSTNAME);
+    }
+}
 
 // ----------------------------------------------------------------------------
 // RRDHOST - internal helpers
 
 static inline void rrdhost_init_tags(RRDHOST *host, const char *tags) {
-    if(host->tags && tags && !strcmp(host->tags, tags))
+    if(host->tags && tags && !strcmp(rrdhost_tags(host), tags))
         return;
 
-    void *old = (void *)host->tags;
-    host->tags = (tags && *tags)?strdupz(tags):NULL;
-    freez(old);
+    STRING *old = host->tags;
+    host->tags = string_strdupz((tags && *tags)?tags:NULL);
+    string_freez(old);
 }
 
 static inline void rrdhost_init_hostname(RRDHOST *host, const char *hostname) {
-    if(host->hostname && hostname && !strcmp(host->hostname, hostname))
+    if(unlikely(hostname && !*hostname)) hostname = NULL;
+
+    if(host->hostname && hostname && !strcmp(rrdhost_hostname(host), hostname))
         return;
 
-    void *old = host->hostname;
-    host->hostname = strdupz(hostname?hostname:"localhost");
-    host->hash_hostname = simple_hash(host->hostname);
-    freez(old);
+    rrdhost_index_del_hostname(host);
+
+    STRING *old = host->hostname;
+    host->hostname = string_strdupz(hostname?hostname:"localhost");
+    string_freez(old);
+
+    rrdhost_index_add_hostname(host);
 }
 
 static inline void rrdhost_init_os(RRDHOST *host, const char *os) {
-    if(host->os && os && !strcmp(host->os, os))
+    if(host->os && os && !strcmp(rrdhost_os(host), os))
         return;
 
-    void *old = (void *)host->os;
-    host->os = strdupz(os?os:"unknown");
-    freez(old);
+    STRING *old = host->os;
+    host->os = string_strdupz(os?os:"unknown");
+    string_freez(old);
 }
 
 static inline void rrdhost_init_timezone(RRDHOST *host, const char *timezone, const char *abbrev_timezone, int32_t utc_offset) {
-    if (host->timezone && timezone && !strcmp(host->timezone, timezone) && host->abbrev_timezone && abbrev_timezone &&
-        !strcmp(host->abbrev_timezone, abbrev_timezone) && host->utc_offset == utc_offset)
+    if (host->timezone && timezone && !strcmp(rrdhost_timezone(host), timezone) && host->abbrev_timezone && abbrev_timezone &&
+        !strcmp(rrdhost_abbrev_timezone(host), abbrev_timezone) && host->utc_offset == utc_offset)
         return;
 
-    void *old = (void *)host->timezone;
-    host->timezone = strdupz((timezone && *timezone)?timezone:"unknown");
-    freez(old);
+    STRING *old = host->timezone;
+    host->timezone = string_strdupz((timezone && *timezone)?timezone:"unknown");
+    string_freez(old);
 
     old = (void *)host->abbrev_timezone;
-    host->abbrev_timezone = strdupz((abbrev_timezone && *abbrev_timezone) ? abbrev_timezone : "UTC");
-    freez(old);
+    host->abbrev_timezone = string_strdupz((abbrev_timezone && *abbrev_timezone) ? abbrev_timezone : "UTC");
+    string_freez(old);
 
     host->utc_offset = utc_offset;
 }
 
-static inline void rrdhost_init_machine_guid(RRDHOST *host, const char *machine_guid) {
-    strncpy(host->machine_guid, machine_guid, GUID_LEN);
-    host->machine_guid[GUID_LEN] = '\0';
-    host->hash_machine_guid = simple_hash(host->machine_guid);
-}
-
-void set_host_properties(RRDHOST *host, int update_every, RRD_MEMORY_MODE memory_mode, const char *hostname,
-                         const char *registry_hostname, const char *guid, const char *os, const char *tags,
+void set_host_properties(RRDHOST *host, int update_every, RRD_MEMORY_MODE memory_mode,
+                         const char *registry_hostname, const char *os, const char *tags,
                          const char *tzone, const char *abbrev_tzone, int32_t utc_offset, const char *program_name,
                          const char *program_version)
 {
@@ -151,23 +188,48 @@ void set_host_properties(RRDHOST *host, int update_every, RRD_MEMORY_MODE memory
     host->rrd_update_every = update_every;
     host->rrd_memory_mode = memory_mode;
 
-    rrdhost_init_hostname(host, hostname);
-
-    rrdhost_init_machine_guid(host, guid);
-
     rrdhost_init_os(host, os);
     rrdhost_init_timezone(host, tzone, abbrev_tzone, utc_offset);
     rrdhost_init_tags(host, tags);
 
-    host->program_name = strdupz((program_name && *program_name) ? program_name : "unknown");
-    host->program_version = strdupz((program_version && *program_version) ? program_version : "unknown");
-
-    host->registry_hostname = strdupz((registry_hostname && *registry_hostname) ? registry_hostname : host->hostname);
+    host->program_name = string_strdupz((program_name && *program_name) ? program_name : "unknown");
+    host->program_version = string_strdupz((program_version && *program_version) ? program_version : "unknown");
+    host->registry_hostname = string_strdupz((registry_hostname && *registry_hostname) ? registry_hostname : rrdhost_hostname(host));
 }
 
 // ----------------------------------------------------------------------------
 // RRDHOST - add a host
 
+static void rrdhost_initialize_rrdpush_sender(RRDHOST *host,
+                                       unsigned int rrdpush_enabled,
+                                       char *rrdpush_destination,
+                                       char *rrdpush_api_key,
+                                       char *rrdpush_send_charts_matching
+) {
+    if(rrdhost_flag_check(host, RRDHOST_FLAG_RRDPUSH_SENDER_INITIALIZED)) return;
+
+    if(rrdpush_enabled && rrdpush_destination && *rrdpush_destination && rrdpush_api_key && *rrdpush_api_key) {
+        rrdhost_flag_set(host, RRDHOST_FLAG_RRDPUSH_SENDER_INITIALIZED);
+
+        sender_init(host);
+
+#ifdef ENABLE_HTTPS
+        host->sender->ssl.conn = NULL;
+        host->sender->ssl.flags = NETDATA_SSL_START;
+#endif
+
+        host->rrdpush_send_destination = strdupz(rrdpush_destination);
+        rrdpush_destinations_init(host);
+
+        host->rrdpush_send_api_key = strdupz(rrdpush_api_key);
+        host->rrdpush_send_charts_matching = simple_pattern_create(rrdpush_send_charts_matching, NULL, SIMPLE_PATTERN_EXACT);
+
+        rrdhost_option_set(host, RRDHOST_OPTION_SENDER_ENABLED);
+    }
+    else
+        rrdhost_option_clear(host, RRDHOST_OPTION_SENDER_ENABLED);
+}
+
 RRDHOST *rrdhost_create(const char *hostname,
                         const char *registry_hostname,
                         const char *guid,
@@ -186,188 +248,136 @@ RRDHOST *rrdhost_create(const char *hostname,
                         char *rrdpush_destination,
                         char *rrdpush_api_key,
                         char *rrdpush_send_charts_matching,
+                        bool rrdpush_enable_replication,
+                        time_t rrdpush_seconds_to_replicate,
+                        time_t rrdpush_replication_step,
                         struct rrdhost_system_info *system_info,
                         int is_localhost,
                         bool archived
 ) {
     debug(D_RRDHOST, "Host '%s': adding with guid '%s'", hostname, guid);
 
+    rrd_check_wrlock();
+
+    if(memory_mode == RRD_MEMORY_MODE_DBENGINE && !dbengine_enabled) {
+        error("memory mode 'dbengine' is not enabled, but host '%s' is configured for it. Falling back to 'alloc'", hostname);
+        memory_mode = RRD_MEMORY_MODE_ALLOC;
+    }
+
 #ifdef ENABLE_DBENGINE
     int is_legacy = (memory_mode == RRD_MEMORY_MODE_DBENGINE) && is_legacy_child(guid);
 #else
-    int is_legacy = 1;
+int is_legacy = 1;
 #endif
-    rrd_check_wrlock();
 
     int is_in_multihost = (memory_mode == RRD_MEMORY_MODE_DBENGINE && !is_legacy);
     RRDHOST *host = callocz(1, sizeof(RRDHOST));
 
-    set_host_properties(host, (update_every > 0)?update_every:1, memory_mode, hostname, registry_hostname, guid, os,
+    strncpyz(host->machine_guid, guid, GUID_LEN + 1);
+
+    set_host_properties(host, (update_every > 0)?update_every:1, memory_mode, registry_hostname, os,
                         tags, timezone, abbrev_timezone, utc_offset, program_name, program_version);
 
+    rrdhost_init_hostname(host, hostname);
+
     host->rrd_history_entries = align_entries_to_pagesize(memory_mode, entries);
     host->health_enabled      = ((memory_mode == RRD_MEMORY_MODE_NONE)) ? 0 : health_enabled;
 
-    sender_init(host);
-    netdata_mutex_init(&host->receiver_lock);
-
-    host->rrdpush_send_enabled     = (rrdpush_enabled && rrdpush_destination && *rrdpush_destination && rrdpush_api_key && *rrdpush_api_key) ? 1 : 0;
-    host->rrdpush_send_destination = (host->rrdpush_send_enabled)?strdupz(rrdpush_destination):NULL;
-    if (host->rrdpush_send_destination)
-        host->destinations = destinations_init(host->rrdpush_send_destination);
-    host->rrdpush_send_api_key     = (host->rrdpush_send_enabled)?strdupz(rrdpush_api_key):NULL;
-    host->rrdpush_send_charts_matching = simple_pattern_create(rrdpush_send_charts_matching, NULL, SIMPLE_PATTERN_EXACT);
+    if (likely(!archived)) {
+        rrdfunctions_init(host);
+        host->rrdlabels = rrdlabels_create();
+        rrdhost_initialize_rrdpush_sender(
+            host, rrdpush_enabled, rrdpush_destination, rrdpush_api_key, rrdpush_send_charts_matching);
+    }
 
-    host->rrdpush_sender_pipe[0] = -1;
-    host->rrdpush_sender_pipe[1] = -1;
-    host->rrdpush_sender_socket  = -1;
+    if(rrdpush_enable_replication)
+        rrdhost_option_set(host, RRDHOST_OPTION_REPLICATION);
+    else
+        rrdhost_option_clear(host, RRDHOST_OPTION_REPLICATION);
+
+    host->rrdpush_seconds_to_replicate = rrdpush_seconds_to_replicate;
+    host->rrdpush_replication_step = rrdpush_replication_step;
+
+    switch(memory_mode) {
+        default:
+        case RRD_MEMORY_MODE_ALLOC:
+        case RRD_MEMORY_MODE_MAP:
+        case RRD_MEMORY_MODE_SAVE:
+        case RRD_MEMORY_MODE_RAM:
+            if(host->rrdpush_seconds_to_replicate > host->rrd_history_entries * host->rrd_update_every)
+                host->rrdpush_seconds_to_replicate = host->rrd_history_entries * host->rrd_update_every;
+            break;
 
-    //host->stream_version = STREAMING_PROTOCOL_CURRENT_VERSION;        Unused?
-#ifdef ENABLE_HTTPS
-    host->ssl.conn = NULL;
-    host->ssl.flags = NETDATA_SSL_START;
-    host->stream_ssl.conn = NULL;
-    host->stream_ssl.flags = NETDATA_SSL_START;
-#endif
+        case RRD_MEMORY_MODE_DBENGINE:
+            break;
+    }
 
     netdata_rwlock_init(&host->rrdhost_rwlock);
-    host->host_labels = rrdlabels_create();
-
     netdata_mutex_init(&host->aclk_state_lock);
+    netdata_mutex_init(&host->receiver_lock);
 
     host->system_info = system_info;
 
-    avl_init_lock(&(host->rrdset_root_index),      rrdset_compare);
-    avl_init_lock(&(host->rrdset_root_index_name), rrdset_compare_name);
-    avl_init_lock(&(host->rrdfamily_root_index),   rrdfamily_compare);
-    avl_init_lock(&(host->rrdvar_root_index),   rrdvar_compare);
+    rrdset_index_init(host);
 
     if(config_get_boolean(CONFIG_SECTION_DB, "delete obsolete charts files", 1))
-        rrdhost_flag_set(host, RRDHOST_FLAG_DELETE_OBSOLETE_CHARTS);
+        rrdhost_option_set(host, RRDHOST_OPTION_DELETE_OBSOLETE_CHARTS);
 
     if(config_get_boolean(CONFIG_SECTION_DB, "delete orphan hosts files", 1) && !is_localhost)
-        rrdhost_flag_set(host, RRDHOST_FLAG_DELETE_ORPHAN_HOST);
-
-    host->health_default_warn_repeat_every = config_get_duration(CONFIG_SECTION_HEALTH, "default repeat warning", "never");
-    host->health_default_crit_repeat_every = config_get_duration(CONFIG_SECTION_HEALTH, "default repeat critical", "never");
-    avl_init_lock(&(host->alarms_idx_health_log), alarm_compare_id);
-    avl_init_lock(&(host->alarms_idx_name), alarm_compare_name);
-
-    // ------------------------------------------------------------------------
-    // initialize health variables
-
-    host->health_log.next_log_id = 1;
-    host->health_log.next_alarm_id = 1;
-    host->health_log.max = 1000;
-    host->health_log.next_log_id = (uint32_t)now_realtime_sec();
-    host->health_log.next_alarm_id = 0;
-
-    long n = config_get_number(CONFIG_SECTION_HEALTH, "in memory max health log entries", host->health_log.max);
-    if(n < 10) {
-        error("Host '%s': health configuration has invalid max log entries %ld. Using default %u", host->hostname, n, host->health_log.max);
-        config_set_number(CONFIG_SECTION_HEALTH, "in memory max health log entries", (long)host->health_log.max);
-    }
-    else
-        host->health_log.max = (unsigned int)n;
-
-    netdata_rwlock_init(&host->health_log.alarm_log_rwlock);
+        rrdhost_option_set(host, RRDHOST_OPTION_DELETE_ORPHAN_HOST);
 
     char filename[FILENAME_MAX + 1];
-
     if(is_localhost) {
-
         host->cache_dir  = strdupz(netdata_configured_cache_dir);
         host->varlib_dir = strdupz(netdata_configured_varlib_dir);
-
     }
     else {
         // this is not localhost - append our GUID to localhost path
         if (is_in_multihost) { // don't append to cache dir in multihost
             host->cache_dir  = strdupz(netdata_configured_cache_dir);
-        } else {
+        }
+        else {
             snprintfz(filename, FILENAME_MAX, "%s/%s", netdata_configured_cache_dir, host->machine_guid);
             host->cache_dir = strdupz(filename);
         }
 
-        if((host->rrd_memory_mode == RRD_MEMORY_MODE_MAP || host->rrd_memory_mode == RRD_MEMORY_MODE_SAVE || (
-           host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE && is_legacy))) {
+        if((host->rrd_memory_mode == RRD_MEMORY_MODE_MAP || host->rrd_memory_mode == RRD_MEMORY_MODE_SAVE ||
+             (host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE && is_legacy))) {
             int r = mkdir(host->cache_dir, 0775);
             if(r != 0 && errno != EEXIST)
-                error("Host '%s': cannot create directory '%s'", host->hostname, host->cache_dir);
+                error("Host '%s': cannot create directory '%s'", rrdhost_hostname(host), host->cache_dir);
         }
 
         snprintfz(filename, FILENAME_MAX, "%s/%s", netdata_configured_varlib_dir, host->machine_guid);
         host->varlib_dir = strdupz(filename);
-
-        if(host->health_enabled) {
-            int r = mkdir(host->varlib_dir, 0775);
-            if(r != 0 && errno != EEXIST)
-                error("Host '%s': cannot create directory '%s'", host->hostname, host->varlib_dir);
-       }
-
-    }
-
-    if(host->health_enabled) {
-        snprintfz(filename, FILENAME_MAX, "%s/health", host->varlib_dir);
-        int r = mkdir(filename, 0775);
-        if(r != 0 && errno != EEXIST)
-            error("Host '%s': cannot create directory '%s'", host->hostname, filename);
-    }
-
-    snprintfz(filename, FILENAME_MAX, "%s/health/health-log.db", host->varlib_dir);
-    host->health_log_filename = strdupz(filename);
-
-    snprintfz(filename, FILENAME_MAX, "%s/alarm-notify.sh", netdata_configured_primary_plugins_dir);
-    host->health_default_exec = strdupz(config_get(CONFIG_SECTION_HEALTH, "script to execute on alarm", filename));
-    host->health_default_recipient = strdupz("root");
-
-
-    // ------------------------------------------------------------------------
-    // load health configuration
-
-    if(host->health_enabled) {
-        rrdhost_wrlock(host);
-        health_readdir(host, health_user_config_dir(), health_stock_config_dir(), NULL);
-        rrdhost_unlock(host);
     }
 
-    RRDHOST *t = rrdhost_index_add(host);
+    // this is also needed for custom host variables - not only health
+    if(!host->rrdvars)
+        host->rrdvars = rrdvariables_create();
 
+    RRDHOST *t = rrdhost_index_add_by_guid(host);
     if(t != host) {
-        error("Host '%s': cannot add host with machine guid '%s' to index. It already exists as host '%s' with machine guid '%s'.", host->hostname, host->machine_guid, t->hostname, t->machine_guid);
+        error("Host '%s': cannot add host with machine guid '%s' to index. It already exists as host '%s' with machine guid '%s'.", rrdhost_hostname(host), host->machine_guid, rrdhost_hostname(t), t->machine_guid);
         rrdhost_free(host, 1);
         return NULL;
     }
 
     if (likely(!uuid_parse(host->machine_guid, host->host_uuid))) {
-        int rc;
-        if (!archived) {
-            rc = sql_store_host_info(host);
-            if (unlikely(rc))
-                error_report("Failed to store machine GUID to the database");
-        }
+        if(!archived)
+            metaqueue_host_update_info(host->machine_guid);
         sql_load_node_id(host);
-        if (host->health_enabled) {
-            if (!file_is_migrated(host->health_log_filename)) {
-                rc = sql_create_health_log_table(host);
-                if (unlikely(rc)) {
-                    error_report("Failed to create health log table in the database");
-                    health_alarm_log_load(host);
-                    health_alarm_log_open(host);
-                }
-                else {
-                    health_alarm_log_load(host);
-                    add_migrated_file(host->health_log_filename, 0);
-                }
-            } else {
-                sql_create_health_log_table(host);
-                sql_health_alarm_log_load(host);
-            }
-        }
     }
     else
         error_report("Host machine GUID %s is not valid", host->machine_guid);
 
+    rrdfamily_index_init(host);
+    rrdcalctemplate_index_init(host);
+    rrdcalc_rrdhost_index_init(host);
+
+    if (health_enabled)
+        health_thread_spawn(host);
+
     if (host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE) {
 #ifdef ENABLE_DBENGINE
         char dbenginepath[FILENAME_MAX + 1];
@@ -376,14 +386,18 @@ RRDHOST *rrdhost_create(const char *hostname,
         snprintfz(dbenginepath, FILENAME_MAX, "%s/dbengine", host->cache_dir);
         ret = mkdir(dbenginepath, 0775);
         if (ret != 0 && errno != EEXIST)
-            error("Host '%s': cannot create directory '%s'", host->hostname, dbenginepath);
+            error("Host '%s': cannot create directory '%s'", rrdhost_hostname(host), dbenginepath);
         else ret = 0; // succeed
         if (is_legacy) {
             // initialize legacy dbengine instance as needed
 
+            host->db[0].mode = RRD_MEMORY_MODE_DBENGINE;
+            host->db[0].eng = storage_engine_get(host->db[0].mode);
+            host->db[0].tier_grouping = get_tier_grouping(0);
+
             ret = rrdeng_init(
                 host,
-                (struct rrdengine_instance **)&host->storage_instance[0],
+                (struct rrdengine_instance **)&host->db[0].instance,
                 dbenginepath,
                 default_rrdeng_page_cache_mb,
                 default_rrdeng_disk_quota_mb,
@@ -392,18 +406,26 @@ RRDHOST *rrdhost_create(const char *hostname,
             if(ret == 0) {
                 // assign the rest of the shared storage instances to it
                 // to allow them collect its metrics too
-                for(int tier = 1; tier < storage_tiers ; tier++)
-                    host->storage_instance[tier] = (STORAGE_INSTANCE *)multidb_ctx[tier];
+                for(size_t tier = 1; tier < storage_tiers ; tier++) {
+                    host->db[tier].mode = RRD_MEMORY_MODE_DBENGINE;
+                    host->db[tier].eng = storage_engine_get(host->db[tier].mode);
+                    host->db[tier].instance = (STORAGE_INSTANCE *) multidb_ctx[tier];
+                    host->db[tier].tier_grouping = get_tier_grouping(tier);
+                }
             }
         }
         else {
-            for(int tier = 0; tier < storage_tiers ; tier++)
-                host->storage_instance[tier] = (STORAGE_INSTANCE *)multidb_ctx[tier];
+            for(size_t tier = 0; tier < storage_tiers ; tier++) {
+                host->db[tier].mode = RRD_MEMORY_MODE_DBENGINE;
+                host->db[tier].eng = storage_engine_get(host->db[tier].mode);
+                host->db[tier].instance = (STORAGE_INSTANCE *)multidb_ctx[tier];
+                host->db[tier].tier_grouping = get_tier_grouping(tier);
+            }
         }
         if (ret) { // check legacy or multihost initialization success
             error(
                 "Host '%s': cannot initialize host with machine guid '%s'. Failed to initialize DB engine at '%s'.",
-                host->hostname, host->machine_guid, host->cache_dir);
+                rrdhost_hostname(host), host->machine_guid, host->cache_dir);
             rrdhost_free(host, 1);
             host = NULL;
             //rrd_hosts_available++; //TODO: maybe we want this?
@@ -416,27 +438,29 @@ RRDHOST *rrdhost_create(const char *hostname,
 #endif
     }
     else {
+        host->db[0].mode = host->rrd_memory_mode;
+        host->db[0].eng = storage_engine_get(host->db[0].mode);
+        host->db[0].instance = NULL;
+        host->db[0].tier_grouping = get_tier_grouping(0);
+
 #ifdef ENABLE_DBENGINE
         // the first tier is reserved for the non-dbengine modes
-        for(int tier = 1; tier < storage_tiers ; tier++)
-            host->storage_instance[tier] = (STORAGE_INSTANCE *)multidb_ctx[tier];
+        for(size_t tier = 1; tier < storage_tiers ; tier++) {
+            host->db[tier].mode = RRD_MEMORY_MODE_DBENGINE;
+            host->db[tier].eng = storage_engine_get(host->db[tier].mode);
+            host->db[tier].instance = (STORAGE_INSTANCE *) multidb_ctx[tier];
+            host->db[tier].tier_grouping = get_tier_grouping(tier);
+        }
 #endif
     }
 
     // ------------------------------------------------------------------------
     // link it and add it to the index
 
-    if(is_localhost) {
-        host->next = localhost;
-        localhost = host;
-    }
-    else {
-        if(localhost) {
-            host->next = localhost->next;
-            localhost->next = host;
-        }
-        else localhost = host;
-    }
+    if(is_localhost)
+        DOUBLE_LINKED_LIST_PREPEND_UNSAFE(localhost, host, prev, next);
+    else
+        DOUBLE_LINKED_LIST_APPEND_UNSAFE(localhost, host, prev, next);
 
     // ------------------------------------------------------------------------
     // init new ML host and update system_info to let upstreams know
@@ -466,28 +490,29 @@ RRDHOST *rrdhost_create(const char *hostname,
                  ", health_log '%s'"
                  ", alarms default handler '%s'"
                  ", alarms default recipient '%s'"
-         , host->hostname
-         , host->registry_hostname
+         , rrdhost_hostname(host)
+         , rrdhost_registry_hostname(host)
          , host->machine_guid
-         , host->os
-         , host->timezone
-         , (host->tags)?host->tags:""
-         , host->program_name
-         , host->program_version
+         , rrdhost_os(host)
+         , rrdhost_timezone(host)
+         , rrdhost_tags(host)
+         , rrdhost_program_name(host)
+         , rrdhost_program_version(host)
          , host->rrd_update_every
          , rrd_memory_mode_name(host->rrd_memory_mode)
          , host->rrd_history_entries
-         , host->rrdpush_send_enabled?"enabled":"disabled"
+         , rrdhost_has_rrdpush_sender_enabled(host)?"enabled":"disabled"
          , host->rrdpush_send_destination?host->rrdpush_send_destination:""
          , host->rrdpush_send_api_key?host->rrdpush_send_api_key:""
          , host->health_enabled?"enabled":"disabled"
          , host->cache_dir
          , host->varlib_dir
          , host->health_log_filename
-         , host->health_default_exec
-         , host->health_default_recipient
+         , string2str(host->health_default_exec)
+         , string2str(host->health_default_recipient)
     );
-    sql_store_host_system_info(&host->host_uuid, system_info);
+    if(!archived)
+        metaqueue_host_update_system_info(host);
 
     rrd_hosts_available++;
 
@@ -496,6 +521,8 @@ RRDHOST *rrdhost_create(const char *hostname,
         ml_new_host(host);
     else
         rrdhost_flag_set(host, RRDHOST_FLAG_ARCHIVED);
+
+
     return host;
 }
 
@@ -518,113 +545,97 @@ void rrdhost_update(RRDHOST *host
                     , char *rrdpush_destination
                     , char *rrdpush_api_key
                     , char *rrdpush_send_charts_matching
+                    , bool rrdpush_enable_replication
+                    , time_t rrdpush_seconds_to_replicate
+                    , time_t rrdpush_replication_step
                     , struct rrdhost_system_info *system_info
 )
 {
     UNUSED(guid);
-    UNUSED(rrdpush_enabled);
-    UNUSED(rrdpush_destination);
-    UNUSED(rrdpush_api_key);
-    UNUSED(rrdpush_send_charts_matching);
 
     host->health_enabled = (mode == RRD_MEMORY_MODE_NONE) ? 0 : health_enabled;
-    //host->stream_version = STREAMING_PROTOCOL_CURRENT_VERSION;        Unused?
 
     rrdhost_system_info_free(host->system_info);
     host->system_info = system_info;
-    sql_store_host_system_info(&host->host_uuid, system_info);
+    metaqueue_host_update_system_info(host);
 
     rrdhost_init_os(host, os);
     rrdhost_init_timezone(host, timezone, abbrev_timezone, utc_offset);
 
-    freez(host->registry_hostname);
-    host->registry_hostname = strdupz((registry_hostname && *registry_hostname)?registry_hostname:hostname);
+    string_freez(host->registry_hostname);
+    host->registry_hostname = string_strdupz((registry_hostname && *registry_hostname)?registry_hostname:hostname);
 
-    if(strcmp(host->hostname, hostname) != 0) {
-        info("Host '%s' has been renamed to '%s'. If this is not intentional it may mean multiple hosts are using the same machine_guid.", host->hostname, hostname);
-        char *t = host->hostname;
-        host->hostname = strdupz(hostname);
-        host->hash_hostname = simple_hash(host->hostname);
-        freez(t);
+    if(strcmp(rrdhost_hostname(host), hostname) != 0) {
+        info("Host '%s' has been renamed to '%s'. If this is not intentional it may mean multiple hosts are using the same machine_guid.", rrdhost_hostname(host), hostname);
+        rrdhost_init_hostname(host, hostname);
     }
 
-    if(strcmp(host->program_name, program_name) != 0) {
-        info("Host '%s' switched program name from '%s' to '%s'", host->hostname, host->program_name, program_name);
-        char *t = host->program_name;
-        host->program_name = strdupz(program_name);
-        freez(t);
+    if(strcmp(rrdhost_program_name(host), program_name) != 0) {
+        info("Host '%s' switched program name from '%s' to '%s'", rrdhost_hostname(host), rrdhost_program_name(host), program_name);
+        STRING *t = host->program_name;
+        host->program_name = string_strdupz(program_name);
+        string_freez(t);
     }
 
-    if(strcmp(host->program_version, program_version) != 0) {
-        info("Host '%s' switched program version from '%s' to '%s'", host->hostname, host->program_version, program_version);
-        char *t = host->program_version;
-        host->program_version = strdupz(program_version);
-        freez(t);
+    if(strcmp(rrdhost_program_version(host), program_version) != 0) {
+        info("Host '%s' switched program version from '%s' to '%s'", rrdhost_hostname(host), rrdhost_program_version(host), program_version);
+        STRING *t = host->program_version;
+        host->program_version = string_strdupz(program_version);
+        string_freez(t);
     }
 
     if(host->rrd_update_every != update_every)
-        error("Host '%s' has an update frequency of %d seconds, but the wanted one is %d seconds. Restart netdata here to apply the new settings.", host->hostname, host->rrd_update_every, update_every);
-
-    if(host->rrd_history_entries < history)
-        error("Host '%s' has history of %ld entries, but the wanted one is %ld entries. Restart netdata here to apply the new settings.", host->hostname, host->rrd_history_entries, history);
+        error("Host '%s' has an update frequency of %d seconds, but the wanted one is %d seconds. Restart netdata here to apply the new settings.", rrdhost_hostname(host), host->rrd_update_every, update_every);
 
     if(host->rrd_memory_mode != mode)
-        error("Host '%s' has memory mode '%s', but the wanted one is '%s'. Restart netdata here to apply the new settings.", host->hostname, rrd_memory_mode_name(host->rrd_memory_mode), rrd_memory_mode_name(mode));
+        error("Host '%s' has memory mode '%s', but the wanted one is '%s'. Restart netdata here to apply the new settings.", rrdhost_hostname(host), rrd_memory_mode_name(host->rrd_memory_mode), rrd_memory_mode_name(mode));
+
+    else if(host->rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE && host->rrd_history_entries < history)
+        error("Host '%s' has history of %ld entries, but the wanted one is %ld entries. Restart netdata here to apply the new settings.", rrdhost_hostname(host), host->rrd_history_entries, history);
 
     // update host tags
     rrdhost_init_tags(host, tags);
 
+    if(!host->rrdvars)
+        host->rrdvars = rrdvariables_create();
+
     if (rrdhost_flag_check(host, RRDHOST_FLAG_ARCHIVED)) {
         rrdhost_flag_clear(host, RRDHOST_FLAG_ARCHIVED);
 
-        host->rrdpush_send_enabled     = (rrdpush_enabled && rrdpush_destination && *rrdpush_destination && rrdpush_api_key && *rrdpush_api_key) ? 1 : 0;
-        host->rrdpush_send_destination = (host->rrdpush_send_enabled)?strdupz(rrdpush_destination):NULL;
-        if (host->rrdpush_send_destination)
-            host->destinations = destinations_init(host->rrdpush_send_destination);
-        host->rrdpush_send_api_key     = (host->rrdpush_send_enabled)?strdupz(rrdpush_api_key):NULL;
-        host->rrdpush_send_charts_matching = simple_pattern_create(rrdpush_send_charts_matching, NULL, SIMPLE_PATTERN_EXACT);
+        rrdfunctions_init(host);
 
-        if(host->health_enabled) {
-            int r;
-            char filename[FILENAME_MAX + 1];
+        if(!host->rrdlabels)
+            host->rrdlabels = rrdlabels_create();
+
+        if (!host->rrdset_root_index)
+            rrdset_index_init(host);
+
+        rrdhost_initialize_rrdpush_sender(host,
+                                   rrdpush_enabled,
+                                   rrdpush_destination,
+                                   rrdpush_api_key,
+                                   rrdpush_send_charts_matching);
+
+        rrdfamily_index_init(host);
+        rrdcalctemplate_index_init(host);
+        rrdcalc_rrdhost_index_init(host);
+
+        if(rrdpush_enable_replication)
+            rrdhost_option_set(host, RRDHOST_OPTION_REPLICATION);
+        else
+            rrdhost_option_clear(host, RRDHOST_OPTION_REPLICATION);
+
+        host->rrdpush_seconds_to_replicate = rrdpush_seconds_to_replicate;
+        host->rrdpush_replication_step = rrdpush_replication_step;
 
-            if (host != localhost) {
-                r = mkdir(host->varlib_dir, 0775);
-                if (r != 0 && errno != EEXIST)
-                    error("Host '%s': cannot create directory '%s'", host->hostname, host->varlib_dir);
-            }
-            snprintfz(filename, FILENAME_MAX, "%s/health", host->varlib_dir);
-            r = mkdir(filename, 0775);
-            if(r != 0 && errno != EEXIST)
-                error("Host '%s': cannot create directory '%s'", host->hostname, filename);
-
-            rrdhost_wrlock(host);
-            health_readdir(host, health_user_config_dir(), health_stock_config_dir(), NULL);
-            rrdhost_unlock(host);
-
-            if (!file_is_migrated(host->health_log_filename)) {
-                int rc = sql_create_health_log_table(host);
-                if (unlikely(rc)) {
-                    error_report("Failed to create health log table in the database");
-
-                    health_alarm_log_load(host);
-                    health_alarm_log_open(host);
-                } else {
-                    health_alarm_log_load(host);
-                    add_migrated_file(host->health_log_filename, 0);
-                }
-            } else {
-                sql_create_health_log_table(host);
-                sql_health_alarm_log_load(host);
-            }
-        }
         rrd_hosts_available++;
         ml_new_host(host);
         rrdhost_load_rrdcontext_data(host);
-        info("Host %s is not in archived mode anymore", host->hostname);
+        info("Host %s is not in archived mode anymore", rrdhost_hostname(host));
     }
 
-    return;
+    if (health_enabled)
+        health_thread_spawn(host);
 }
 
 RRDHOST *rrdhost_find_or_create(
@@ -646,17 +657,20 @@ RRDHOST *rrdhost_find_or_create(
         , char *rrdpush_destination
         , char *rrdpush_api_key
         , char *rrdpush_send_charts_matching
+        , bool rrdpush_enable_replication
+        , time_t rrdpush_seconds_to_replicate
+        , time_t rrdpush_replication_step
         , struct rrdhost_system_info *system_info
         , bool archived
 ) {
     debug(D_RRDHOST, "Searching for host '%s' with guid '%s'", hostname, guid);
 
     rrd_wrlock();
-    RRDHOST *host = rrdhost_find_by_guid(guid, 0);
-    if (unlikely(host && RRD_MEMORY_MODE_DBENGINE != mode && rrdhost_flag_check(host, RRDHOST_FLAG_ARCHIVED))) {
+    RRDHOST *host = rrdhost_find_by_guid(guid);
+    if (unlikely(host && host->rrd_memory_mode != mode && rrdhost_flag_check(host, RRDHOST_FLAG_ARCHIVED))) {
         /* If a legacy memory mode instantiates all dbengine state must be discarded to avoid inconsistencies */
         error("Archived host '%s' has memory mode '%s', but the wanted one is '%s'. Discarding archived state.",
-              host->hostname, rrd_memory_mode_name(host->rrd_memory_mode), rrd_memory_mode_name(mode));
+              rrdhost_hostname(host), rrd_memory_mode_name(host->rrd_memory_mode), rrd_memory_mode_name(mode));
         rrdhost_free(host, 1);
         host = NULL;
     }
@@ -680,6 +694,9 @@ RRDHOST *rrdhost_find_or_create(
                 , rrdpush_destination
                 , rrdpush_api_key
                 , rrdpush_send_charts_matching
+                , rrdpush_enable_replication
+                , rrdpush_seconds_to_replicate
+                , rrdpush_replication_step
                 , system_info
                 , 0
                 , archived
@@ -705,6 +722,9 @@ RRDHOST *rrdhost_find_or_create(
            , rrdpush_destination
            , rrdpush_api_key
            , rrdpush_send_charts_matching
+           , rrdpush_enable_replication
+           , rrdpush_seconds_to_replicate
+           , rrdpush_replication_step
            , system_info);
     }
     if (host) {
@@ -721,6 +741,8 @@ RRDHOST *rrdhost_find_or_create(
 inline int rrdhost_should_be_removed(RRDHOST *host, RRDHOST *protected_host, time_t now) {
     if(host != protected_host
        && host != localhost
+       && rrdhost_receiver_replicating_charts(host) == 0
+       && rrdhost_sender_replicating_charts(host) == 0
        && rrdhost_flag_check(host, RRDHOST_FLAG_ORPHAN)
        && !rrdhost_flag_check(host, RRDHOST_FLAG_ARCHIVED)
        && !host->receiver
@@ -731,50 +753,10 @@ inline int rrdhost_should_be_removed(RRDHOST *host, RRDHOST *protected_host, tim
     return 0;
 }
 
-void rrdhost_cleanup_orphan_hosts_nolock(RRDHOST *protected_host) {
-    time_t now = now_realtime_sec();
-
-    RRDHOST *host;
-
-restart_after_removal:
-    rrdhost_foreach_write(host) {
-        if(rrdhost_should_be_removed(host, protected_host, now)) {
-            info("Host '%s' with machine guid '%s' is obsolete - cleaning up.", host->hostname, host->machine_guid);
-
-            if (rrdhost_flag_check(host, RRDHOST_FLAG_DELETE_ORPHAN_HOST)
-#ifdef ENABLE_DBENGINE
-                /* don't delete multi-host DB host files */
-                && !(host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE && is_storage_engine_shared(host->storage_instance[0]))
-#endif
-            )
-                rrdhost_delete_charts(host);
-            else
-                rrdhost_save_charts(host);
-
-            rrdhost_free(host, 0);
-            goto restart_after_removal;
-        }
-    }
-}
-
 // ----------------------------------------------------------------------------
 // RRDHOST global / startup initialization
 
-int rrd_init(char *hostname, struct rrdhost_system_info *system_info) {
-
-    if (unlikely(sql_init_database(DB_CHECK_NONE, system_info ? 0 : 1))) {
-        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            fatal("Failed to initialize SQLite");
-        info("Skipping SQLITE metadata initialization since memory mode is not dbengine");
-    }
-
-    if (unlikely(sql_init_context_database(system_info ? 0 : 1))) {
-        error_report("Failed to initialize context metadata database");
-    }
-
-    if (unlikely(!system_info))
-        goto unittest;
-
+void dbengine_init(char *hostname) {
 #ifdef ENABLE_DBENGINE
     storage_tiers = config_get_number(CONFIG_SECTION_DB, "storage tiers", storage_tiers);
     if(storage_tiers < 1) {
@@ -807,14 +789,15 @@ int rrd_init(char *hostname, struct rrdhost_system_info *system_info) {
     else
         rrdeng_page_descr_use_malloc();
 
-    int created_tiers = 0;
+    size_t created_tiers = 0;
     char dbenginepath[FILENAME_MAX + 1];
     char dbengineconfig[200 + 1];
-    for(int tier = 0; tier < storage_tiers ;tier++) {
+    int divisor = 1;
+    for(size_t tier = 0; tier < storage_tiers ;tier++) {
         if(tier == 0)
             snprintfz(dbenginepath, FILENAME_MAX, "%s/dbengine", netdata_configured_cache_dir);
         else
-            snprintfz(dbenginepath, FILENAME_MAX, "%s/dbengine-tier%d", netdata_configured_cache_dir, tier);
+            snprintfz(dbenginepath, FILENAME_MAX, "%s/dbengine-tier%zu", netdata_configured_cache_dir, tier);
 
         int ret = mkdir(dbenginepath, 0775);
         if (ret != 0 && errno != EEXIST) {
@@ -822,27 +805,30 @@ int rrd_init(char *hostname, struct rrdhost_system_info *system_info) {
             break;
         }
 
-        int page_cache_mb = default_rrdeng_page_cache_mb;
-        int disk_space_mb = default_multidb_disk_quota_mb;
-        int grouping_iterations = storage_tiers_grouping_iterations[tier];
+        if(tier > 0)
+            divisor *= 2;
+
+        int page_cache_mb = default_rrdeng_page_cache_mb / divisor;
+        int disk_space_mb = default_multidb_disk_quota_mb / divisor;
+        size_t grouping_iterations = storage_tiers_grouping_iterations[tier];
         RRD_BACKFILL backfill = storage_tiers_backfill[tier];
 
         if(tier > 0) {
-            snprintfz(dbengineconfig, 200, "dbengine tier %d page cache size MB", tier);
+            snprintfz(dbengineconfig, 200, "dbengine tier %zu page cache size MB", tier);
             page_cache_mb = config_get_number(CONFIG_SECTION_DB, dbengineconfig, page_cache_mb);
 
-            snprintfz(dbengineconfig, 200, "dbengine tier %d multihost disk space MB", tier);
+            snprintfz(dbengineconfig, 200, "dbengine tier %zu multihost disk space MB", tier);
             disk_space_mb = config_get_number(CONFIG_SECTION_DB, dbengineconfig, disk_space_mb);
 
-            snprintfz(dbengineconfig, 200, "dbengine tier %d update every iterations", tier);
+            snprintfz(dbengineconfig, 200, "dbengine tier %zu update every iterations", tier);
             grouping_iterations = config_get_number(CONFIG_SECTION_DB, dbengineconfig, grouping_iterations);
             if(grouping_iterations < 2) {
                 grouping_iterations = 2;
                 config_set_number(CONFIG_SECTION_DB, dbengineconfig, grouping_iterations);
-                error("DBENGINE on '%s': 'dbegnine tier %d update every iterations' cannot be less than 2. Assuming 2.", hostname, tier);
+                error("DBENGINE on '%s': 'dbegnine tier %zu update every iterations' cannot be less than 2. Assuming 2.", hostname, tier);
             }
 
-            snprintfz(dbengineconfig, 200, "dbengine tier %d backfill", tier);
+            snprintfz(dbengineconfig, 200, "dbengine tier %zu backfill", tier);
             const char *bf = config_get(CONFIG_SECTION_DB, dbengineconfig, backfill == RRD_BACKFILL_NEW ? "new" : backfill == RRD_BACKFILL_FULL ? "full" : "none");
             if(strcmp(bf, "new") == 0) backfill = RRD_BACKFILL_NEW;
             else if(strcmp(bf, "full") == 0) backfill = RRD_BACKFILL_FULL;
@@ -859,14 +845,14 @@ int rrd_init(char *hostname, struct rrdhost_system_info *system_info) {
 
         if(tier > 0 && get_tier_grouping(tier) > 65535) {
             storage_tiers_grouping_iterations[tier] = 1;
-            error("DBENGINE on '%s': dbengine tier %d gives aggregation of more than 65535 points of tier 0. Disabling tiers above %d", hostname, tier, tier);
+            error("DBENGINE on '%s': dbengine tier %zu gives aggregation of more than 65535 points of tier 0. Disabling tiers above %zu", hostname, tier, tier);
             break;
         }
-        
-        internal_error(true, "DBENGINE tier %d grouping iterations is set to %d", tier, storage_tiers_grouping_iterations[tier]);
+
+        internal_error(true, "DBENGINE tier %zu grouping iterations is set to %zu", tier, storage_tiers_grouping_iterations[tier]);
         ret = rrdeng_init(NULL, NULL, dbenginepath, page_cache_mb, disk_space_mb, tier);
         if(ret != 0) {
-            error("DBENGINE on '%s': Failed to initialize multi-host database tier %d on path '%s'",
+            error("DBENGINE on '%s': Failed to initialize multi-host database tier %zu on path '%s'",
                   hostname, tier, dbenginepath);
             break;
         }
@@ -875,13 +861,14 @@ int rrd_init(char *hostname, struct rrdhost_system_info *system_info) {
     }
 
     if(created_tiers && created_tiers < storage_tiers) {
-        error("DBENGINE on '%s': Managed to create %d tiers instead of %d. Continuing with %d available.",
+        error("DBENGINE on '%s': Managed to create %zu tiers instead of %zu. Continuing with %zu available.",
               hostname, created_tiers, storage_tiers, created_tiers);
         storage_tiers = created_tiers;
     }
     else if(!created_tiers)
         fatal("DBENGINE on '%s', failed to initialize databases at '%s'.", hostname, netdata_configured_cache_dir);
 
+    dbengine_enabled = true;
 #else
     storage_tiers = config_get_number(CONFIG_SECTION_DB, "storage tiers", 1);
     if(storage_tiers != 1) {
@@ -889,12 +876,54 @@ int rrd_init(char *hostname, struct rrdhost_system_info *system_info) {
         storage_tiers = 1;
         config_set_number(CONFIG_SECTION_DB, "storage tiers", storage_tiers);
     }
+    dbengine_enabled = false;
 #endif
+}
 
-    health_init();
-    rrdpush_init();
+int rrd_init(char *hostname, struct rrdhost_system_info *system_info) {
+    rrdhost_init();
 
-unittest:
+    if (unlikely(sql_init_database(DB_CHECK_NONE, system_info ? 0 : 1))) {
+        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
+            fatal("Failed to initialize SQLite");
+        info("Skipping SQLITE metadata initialization since memory mode is not dbengine");
+    }
+
+    if (unlikely(sql_init_context_database(system_info ? 0 : 1))) {
+        error_report("Failed to initialize context metadata database");
+    }
+
+    if (unlikely(strcmp(hostname, "unittest") == 0)) {
+        dbengine_enabled = true;
+    }
+    else {
+        health_init();
+        rrdpush_init();
+
+        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE || rrdpush_receiver_needs_dbengine()) {
+            info("Initializing dbengine...");
+            dbengine_init(hostname);
+        }
+        else {
+            info("Not initializing dbengine...");
+            storage_tiers = 1;
+        }
+
+        if (!dbengine_enabled) {
+            if (storage_tiers > 1) {
+                error("dbengine is not enabled, but %zu tiers have been requested. Resetting tiers to 1",
+                      storage_tiers);
+                storage_tiers = 1;
+            }
+
+            if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE) {
+                error("dbengine is not enabled, but it has been given as the default db mode. Resetting db mode to alloc");
+                default_rrd_memory_mode = RRD_MEMORY_MODE_ALLOC;
+            }
+        }
+    }
+
+    metadata_sync_init();
     debug(D_RRDHOST, "Initializing localhost with hostname '%s'", hostname);
     rrd_wrlock();
     localhost = rrdhost_create(
@@ -916,6 +945,9 @@ unittest:
         , default_rrdpush_destination
         , default_rrdpush_api_key
         , default_rrdpush_send_charts_matching
+        , default_rrdpush_enable_replication
+        , default_rrdpush_seconds_to_replicate
+        , default_rrdpush_replication_step
         , system_info
         , 1
         , 0
@@ -940,19 +972,19 @@ unittest:
 // there are only used when NETDATA_INTERNAL_CHECKS is set
 
 void __rrdhost_check_rdlock(RRDHOST *host, const char *file, const char *function, const unsigned long line) {
-    debug(D_RRDHOST, "Checking read lock on host '%s'", host->hostname);
+    debug(D_RRDHOST, "Checking read lock on host '%s'", rrdhost_hostname(host));
 
     int ret = netdata_rwlock_trywrlock(&host->rrdhost_rwlock);
     if(ret == 0)
-        fatal("RRDHOST '%s' should be read-locked, but it is not, at function %s() at line %lu of file '%s'", host->hostname, function, line, file);
+        fatal("RRDHOST '%s' should be read-locked, but it is not, at function %s() at line %lu of file '%s'", rrdhost_hostname(host), function, line, file);
 }
 
 void __rrdhost_check_wrlock(RRDHOST *host, const char *file, const char *function, const unsigned long line) {
-    debug(D_RRDHOST, "Checking write lock on host '%s'", host->hostname);
+    debug(D_RRDHOST, "Checking write lock on host '%s'", rrdhost_hostname(host));
 
     int ret = netdata_rwlock_tryrdlock(&host->rrdhost_rwlock);
     if(ret == 0)
-        fatal("RRDHOST '%s' should be write-locked, but it is not, at function %s() at line %lu of file '%s'", host->hostname, function, line, file);
+        fatal("RRDHOST '%s' should be write-locked, but it is not, at function %s() at line %lu of file '%s'", rrdhost_hostname(host), function, line, file);
 }
 
 void __rrd_check_rdlock(const char *file, const char *function, const unsigned long line) {
@@ -975,8 +1007,6 @@ void __rrd_check_wrlock(const char *file, const char *function, const unsigned l
 // RRDHOST - free
 
 void rrdhost_system_info_free(struct rrdhost_system_info *system_info) {
-    info("SYSTEM_INFO: free %p", system_info);
-
     if(likely(system_info)) {
         freez(system_info->cloud_provider_type);
         freez(system_info->cloud_instance_type);
@@ -1016,18 +1046,21 @@ void destroy_receiver_state(struct receiver_state *rpt);
 
 void stop_streaming_sender(RRDHOST *host)
 {
+    rrdhost_option_clear(host, RRDHOST_OPTION_SENDER_ENABLED);
+
     if (unlikely(!host->sender))
         return;
 
     rrdpush_sender_thread_stop(host); // stop a possibly running thread
     cbuffer_free(host->sender->buffer);
-    buffer_free(host->sender->build);
 #ifdef ENABLE_COMPRESSION
     if (host->sender->compressor)
         host->sender->compressor->destroy(&host->sender->compressor);
 #endif
+    replication_cleanup_sender(host->sender);
     freez(host->sender);
     host->sender = NULL;
+    rrdhost_flag_clear(host, RRDHOST_FLAG_RRDPUSH_SENDER_INITIALIZED);
 }
 
 void stop_streaming_receiver(RRDHOST *host)
@@ -1051,7 +1084,7 @@ void rrdhost_free(RRDHOST *host, bool force) {
     if(!host) return;
 
     if (netdata_exit || force)
-        info("Freeing all memory for host '%s'...", host->hostname);
+        info("Freeing all memory for host '%s'...", rrdhost_hostname(host));
 
     rrd_check_wrlock();     // make sure the RRDs are write locked
 
@@ -1061,65 +1094,53 @@ void rrdhost_free(RRDHOST *host, bool force) {
 
     // ------------------------------------------------------------------------
     // clean up streaming
+
     stop_streaming_sender(host);
 
     if (netdata_exit || force)
         stop_streaming_receiver(host);
 
+
+    // ------------------------------------------------------------------------
+    // clean up alarms
+
+    rrdcalc_delete_all(host);
+
+
     rrdhost_wrlock(host);   // lock this RRDHOST
+
     // ------------------------------------------------------------------------
     // release its children resources
 
 #ifdef ENABLE_DBENGINE
-    for(int tier = 0; tier < storage_tiers ;tier++) {
-        if(host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE &&
-            host->storage_instance[tier] &&
-            !is_storage_engine_shared(host->storage_instance[tier]))
-            rrdeng_prepare_exit((struct rrdengine_instance *)host->storage_instance[tier]);
+    for(size_t tier = 0; tier < storage_tiers ;tier++) {
+        if(host->db[tier].mode == RRD_MEMORY_MODE_DBENGINE
+            && host->db[tier].instance
+            && !is_storage_engine_shared(host->db[tier].instance))
+            rrdeng_prepare_exit((struct rrdengine_instance *)host->db[tier].instance);
     }
 #endif
 
-    while(host->rrdset_root)
-        rrdset_free(host->rrdset_root);
+    // delete all the RRDSETs of the host
+    rrdset_index_destroy(host);
+    rrdcalc_rrdhost_index_destroy(host);
+    rrdcalctemplate_index_destroy(host);
 
     freez(host->exporting_flags);
 
-    while(host->alarms)
-        rrdcalc_unlink_and_free(host, host->alarms);
-
-    RRDCALC *rc,*nc;
-    for(rc = host->alarms_with_foreach; rc ; rc = nc) {
-        nc = rc->next;
-        rrdcalc_free(rc);
-    }
-    host->alarms_with_foreach = NULL;
-
-    while(host->templates)
-        rrdcalctemplate_unlink_and_free(host, host->templates);
-
-    RRDCALCTEMPLATE *rt,*next;
-    for(rt = host->alarms_template_with_foreach; rt ; rt = next) {
-        next = rt->next;
-        rrdcalctemplate_free(rt);
-    }
-    host->alarms_template_with_foreach = NULL;
-
-    debug(D_RRD_CALLS, "RRDHOST: Cleaning up remaining host variables for host '%s'", host->hostname);
-    rrdvar_free_remaining_variables(host, &host->rrdvar_root_index);
-
     health_alarm_log_free(host);
 
 #ifdef ENABLE_DBENGINE
-    for(int tier = 0; tier < storage_tiers ;tier++) {
-        if(host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE &&
-            host->storage_instance[tier] &&
-            !is_storage_engine_shared(host->storage_instance[tier]))
-            rrdeng_exit((struct rrdengine_instance *)host->storage_instance[tier]);
+    for(size_t tier = 0; tier < storage_tiers ;tier++) {
+        if(host->db[tier].mode == RRD_MEMORY_MODE_DBENGINE
+            && host->db[tier].instance
+            && !is_storage_engine_shared(host->db[tier].instance))
+            rrdeng_exit((struct rrdengine_instance *)host->db[tier].instance);
     }
 #endif
 
     if (!netdata_exit && !force) {
-        info("Setting archive mode for host '%s'...", host->hostname);
+        info("Setting archive mode for host '%s'...", rrdhost_hostname(host));
         rrdhost_flag_set(host, RRDHOST_FLAG_ARCHIVED);
         rrdhost_unlock(host);
         return;
@@ -1143,24 +1164,13 @@ void rrdhost_free(RRDHOST *host, bool force) {
     // ------------------------------------------------------------------------
     // remove it from the indexes
 
-    if(rrdhost_index_del(host) != host)
-        error("RRDHOST '%s' removed from index, deleted the wrong entry.", host->hostname);
+    rrdhost_index_del_hostname(host);
+    rrdhost_index_del_by_guid(host);
 
     // ------------------------------------------------------------------------
     // unlink it from the host
 
-    if(host == localhost) {
-        localhost = host->next;
-    }
-    else {
-        // find the previous one
-        RRDHOST *h;
-        for(h = localhost; h && h->next != host ; h = h->next) ;
-
-        // bypass it
-        if(h) h->next = host->next;
-        else error("Request to free RRDHOST '%s': cannot find it", host->hostname);
-    }
+    DOUBLE_LINKED_LIST_REMOVE_UNSAFE(localhost, host, prev, next);
 
     // ------------------------------------------------------------------------
     // free it
@@ -1168,37 +1178,36 @@ void rrdhost_free(RRDHOST *host, bool force) {
     pthread_mutex_destroy(&host->aclk_state_lock);
     freez(host->aclk_state.claimed_id);
     freez(host->aclk_state.prev_claimed_id);
-    freez((void *)host->tags);
-    rrdlabels_destroy(host->host_labels);
-    freez((void *)host->os);
-    freez((void *)host->timezone);
-    freez((void *)host->abbrev_timezone);
-    freez(host->program_version);
-    freez(host->program_name);
+    string_freez(host->tags);
+    rrdlabels_destroy(host->rrdlabels);
+    string_freez(host->os);
+    string_freez(host->timezone);
+    string_freez(host->abbrev_timezone);
+    string_freez(host->program_name);
+    string_freez(host->program_version);
     rrdhost_system_info_free(host->system_info);
     freez(host->cache_dir);
     freez(host->varlib_dir);
     freez(host->rrdpush_send_api_key);
     freez(host->rrdpush_send_destination);
-    struct rrdpush_destinations *tmp_destination;
-    while (host->destinations) {
-        tmp_destination = host->destinations->next;
-        freez(host->destinations);
-        host->destinations = tmp_destination;
-    }
-    freez(host->health_default_exec);
-    freez(host->health_default_recipient);
+    rrdpush_destinations_free(host);
+    string_freez(host->health_default_exec);
+    string_freez(host->health_default_recipient);
     freez(host->health_log_filename);
-    freez(host->hostname);
-    freez(host->registry_hostname);
+    string_freez(host->registry_hostname);
     simple_pattern_free(host->rrdpush_send_charts_matching);
     rrdhost_unlock(host);
     netdata_rwlock_destroy(&host->health_log.alarm_log_rwlock);
     netdata_rwlock_destroy(&host->rrdhost_rwlock);
     freez(host->node_id);
 
+    rrdfamily_index_destroy(host);
+    rrdfunctions_destroy(host);
+    rrdvariables_destroy(host->rrdvars);
+
     rrdhost_destroy_rrdcontexts(host);
 
+    string_freez(host->hostname);
     freez(host);
 #ifdef ENABLE_ACLK
     if (wc)
@@ -1209,9 +1218,14 @@ void rrdhost_free(RRDHOST *host, bool force) {
 
 void rrdhost_free_all(void) {
     rrd_wrlock();
+
     /* Make sure child-hosts are released before the localhost. */
-    while(localhost->next) rrdhost_free(localhost->next, 1);
-    rrdhost_free(localhost, 1);
+    while(localhost && localhost->next)
+        rrdhost_free(localhost->next, 1);
+
+    if(localhost)
+        rrdhost_free(localhost, 1);
+
     rrd_unlock();
 }
 
@@ -1221,25 +1235,20 @@ void rrdhost_free_all(void) {
 void rrdhost_save_charts(RRDHOST *host) {
     if(!host) return;
 
-    info("Saving/Closing database of host '%s'...", host->hostname);
+    info("Saving/Closing database of host '%s'...", rrdhost_hostname(host));
 
     RRDSET *st;
 
     // we get a write lock
     // to ensure only one thread is saving the database
-    rrdhost_wrlock(host);
-
     rrdset_foreach_write(st, host) {
-        rrdset_rdlock(st);
         rrdset_save(st);
-        rrdset_unlock(st);
     }
-
-    rrdhost_unlock(host);
+    rrdset_foreach_done(st);
 }
 
 static void rrdhost_load_auto_labels(void) {
-    DICTIONARY *labels = localhost->host_labels;
+    DICTIONARY *labels = localhost->rrdlabels;
 
     if (localhost->system_info->cloud_provider_type)
         rrdlabels_add(labels, "_cloud_provider_type", localhost->system_info->cloud_provider_type, RRDLABEL_SRC_AUTO);
@@ -1301,13 +1310,31 @@ static void rrdhost_load_auto_labels(void) {
 
     add_aclk_host_labels();
 
+    health_add_host_labels();
+
     rrdlabels_add(
-        labels, "_is_parent", (localhost->next || configured_as_parent()) ? "true" : "false", RRDLABEL_SRC_AUTO);
+        labels, "_is_parent", (localhost->senders_count > 0) ? "true" : "false", RRDLABEL_SRC_AUTO);
 
     if (localhost->rrdpush_send_destination)
         rrdlabels_add(labels, "_streams_to", localhost->rrdpush_send_destination, RRDLABEL_SRC_AUTO);
 }
 
+void rrdhost_set_is_parent_label(int count) {
+    DICTIONARY *labels = localhost->rrdlabels;
+
+    if (count == 0 || count == 1) {
+        rrdlabels_add(
+                      labels, "_is_parent", (count) ? "true" : "false", RRDLABEL_SRC_AUTO);
+
+        //queue a node info
+#ifdef ENABLE_ACLK
+        if (netdata_cloud_setting) {
+            aclk_queue_node_info(localhost);
+        }
+#endif
+    }
+}
+
 static void rrdhost_load_config_labels(void) {
     int status = config_load(NULL, 1, CONFIG_SECTION_HOST_LABEL);
     if(!status) {
@@ -1320,7 +1347,7 @@ static void rrdhost_load_config_labels(void) {
         config_section_wrlock(co);
         struct config_option *cv;
         for(cv = co->values; cv ; cv = cv->next) {
-            rrdlabels_add(localhost->host_labels, cv->name, cv->value, RRDLABEL_SRC_CONFIG);
+            rrdlabels_add(localhost->rrdlabels, cv->name, cv->value, RRDLABEL_SRC_CONFIG);
             cv->flags |= CONFIG_VALUE_USED;
         }
         config_section_unlock(co);
@@ -1339,41 +1366,37 @@ static void rrdhost_load_kubernetes_labels(void) {
     debug(D_RRDHOST, "Attempting to fetch external labels via %s", label_script);
 
     pid_t pid;
-    FILE *fp = mypopen(label_script, &pid);
-    if(!fp) return;
+    FILE *fp_child_input;
+    FILE *fp_child_output = netdata_popen(label_script, &pid, &fp_child_input);
+    if(!fp_child_output) return;
 
     char buffer[1000 + 1];
-    while (fgets(buffer, 1000, fp) != NULL)
-        rrdlabels_add_pair(localhost->host_labels, buffer, RRDLABEL_SRC_AUTO|RRDLABEL_SRC_K8S);
+    while (fgets(buffer, 1000, fp_child_output) != NULL)
+        rrdlabels_add_pair(localhost->rrdlabels, buffer, RRDLABEL_SRC_AUTO|RRDLABEL_SRC_K8S);
 
     // Non-zero exit code means that all the script output is error messages. We've shown already any message that didn't include a ':'
     // Here we'll inform with an ERROR that the script failed, show whatever (if anything) was added to the list of labels, free the memory and set the return to null
-    int rc = mypclose(fp, pid);
+    int rc = netdata_pclose(fp_child_input, fp_child_output, pid);
     if(rc) error("%s exited abnormally. Failed to get kubernetes labels.", label_script);
 }
 
 void reload_host_labels(void) {
-    if(!localhost->host_labels)
-        localhost->host_labels = rrdlabels_create();
+    if(!localhost->rrdlabels)
+        localhost->rrdlabels = rrdlabels_create();
 
-    rrdlabels_unmark_all(localhost->host_labels);
+    rrdlabels_unmark_all(localhost->rrdlabels);
 
     // priority is important here
     rrdhost_load_config_labels();
     rrdhost_load_kubernetes_labels();
     rrdhost_load_auto_labels();
 
-    rrdlabels_remove_all_unmarked(localhost->host_labels);
-    sql_store_host_labels(localhost);
+    rrdlabels_remove_all_unmarked(localhost->rrdlabels);
+    metaqueue_store_host_labels(localhost->machine_guid);
 
     health_label_log_save(localhost);
 
-/*  TODO-GAPS - fix this so that it looks properly at the state and version of the sender
-    if(localhost->rrdpush_send_enabled && localhost->rrdpush_sender_buffer){
-        localhost->labels.labels_flag |= RRDHOST_FLAG_STREAM_LABELS_UPDATE;
-        rrdpush_send_labels(localhost);
-    }
-*/
+    rrdpush_send_host_labels(localhost);
     health_reload();
 }
 
@@ -1383,23 +1406,18 @@ void reload_host_labels(void) {
 void rrdhost_delete_charts(RRDHOST *host) {
     if(!host) return;
 
-    info("Deleting database of host '%s'...", host->hostname);
+    info("Deleting database of host '%s'...", rrdhost_hostname(host));
 
     RRDSET *st;
 
     // we get a write lock
     // to ensure only one thread is saving the database
-    rrdhost_wrlock(host);
-
     rrdset_foreach_write(st, host) {
-        rrdset_rdlock(st);
-        rrdset_delete_files(st);
-        rrdset_unlock(st);
+            rrdset_delete_files(st);
     }
+    rrdset_foreach_done(st);
 
     recursively_delete_dir(host->cache_dir, "left over host");
-
-    rrdhost_unlock(host);
 }
 
 // ----------------------------------------------------------------------------
@@ -1408,29 +1426,26 @@ void rrdhost_delete_charts(RRDHOST *host) {
 void rrdhost_cleanup_charts(RRDHOST *host) {
     if(!host) return;
 
-    info("Cleaning up database of host '%s'...", host->hostname);
+    info("Cleaning up database of host '%s'...", rrdhost_hostname(host));
 
     RRDSET *st;
-    uint32_t rrdhost_delete_obsolete_charts = rrdhost_flag_check(host, RRDHOST_FLAG_DELETE_OBSOLETE_CHARTS);
+    uint32_t rrdhost_delete_obsolete_charts = rrdhost_option_check(host, RRDHOST_OPTION_DELETE_OBSOLETE_CHARTS);
 
     // we get a write lock
     // to ensure only one thread is saving the database
-    rrdhost_wrlock(host);
-
     rrdset_foreach_write(st, host) {
-        rrdset_rdlock(st);
 
         if(rrdhost_delete_obsolete_charts && rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE))
             rrdset_delete_files(st);
+
         else if(rrdhost_delete_obsolete_charts && rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE_DIMENSIONS))
             rrdset_delete_obsolete_dimensions(st);
+
         else
             rrdset_save(st);
 
-        rrdset_unlock(st);
     }
-
-    rrdhost_unlock(host);
+    rrdset_foreach_done(st);
 }
 
 
@@ -1459,11 +1474,9 @@ void rrdhost_cleanup_all(void) {
 
     RRDHOST *host;
     rrdhost_foreach_read(host) {
-        if (host != localhost && rrdhost_flag_check(host, RRDHOST_FLAG_DELETE_ORPHAN_HOST) && !host->receiver
-#ifdef ENABLE_DBENGINE
+        if (host != localhost && rrdhost_option_check(host, RRDHOST_OPTION_DELETE_ORPHAN_HOST) && !host->receiver
             /* don't delete multi-host DB host files */
-            && !(host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE && is_storage_engine_shared(host->storage_instance[0]))
-#endif
+            && !(host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE && is_storage_engine_shared(host->db[0].instance))
         )
             rrdhost_delete_charts(host);
         else
@@ -1475,157 +1488,6 @@ void rrdhost_cleanup_all(void) {
 
 
 // ----------------------------------------------------------------------------
-// RRDHOST - save or delete all the host charts from disk
-
-void rrdhost_cleanup_obsolete_charts(RRDHOST *host) {
-    time_t now = now_realtime_sec();
-
-    RRDSET *st;
-
-    uint32_t rrdhost_delete_obsolete_charts = rrdhost_flag_check(host, RRDHOST_FLAG_DELETE_OBSOLETE_CHARTS);
-
-restart_after_removal:
-    rrdset_foreach_write(st, host) {
-        if(unlikely(rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE)
-                    && st->last_accessed_time + rrdset_free_obsolete_time < now
-                    && st->last_updated.tv_sec + rrdset_free_obsolete_time < now
-                    && st->last_collected_time.tv_sec + rrdset_free_obsolete_time < now
-        )) {
-            st->rrdhost->obsolete_charts_count--;
-#ifdef ENABLE_DBENGINE
-            if(st->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE) {
-                RRDDIM *rd, *last;
-
-                rrdset_flag_set(st, RRDSET_FLAG_ARCHIVED);
-                while (st->variables)  rrdsetvar_free(st->variables);
-                while (st->alarms)     rrdsetcalc_unlink(st->alarms);
-                rrdset_wrlock(st);
-                for (rd = st->dimensions, last = NULL ; likely(rd) ; ) {
-                    if (rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)) {
-                        last = rd;
-                        rd = rd->next;
-                        continue;
-                    }
-
-                    if (rrddim_flag_check(rd, RRDDIM_FLAG_ACLK)) {
-                        last = rd;
-                        rd = rd->next;
-                        continue;
-                    }
-                    rrddim_flag_set(rd, RRDDIM_FLAG_ARCHIVED);
-                    while (rd->variables)
-                        rrddimvar_free(rd->variables);
-
-                    if (rrddim_flag_check(rd, RRDDIM_FLAG_OBSOLETE)) {
-                        rrddim_flag_clear(rd, RRDDIM_FLAG_OBSOLETE);
-
-                        /* only a collector can mark a chart as obsolete, so we must remove the reference */
-
-                        size_t tiers_available = 0, tiers_said_yes = 0;
-                        for(int tier = 0; tier < storage_tiers ;tier++) {
-                            if(rd->tiers[tier]) {
-                                tiers_available++;
-
-                                if(rd->tiers[tier]->collect_ops.finalize(rd->tiers[tier]->db_collection_handle))
-                                    tiers_said_yes++;
-
-                                rd->tiers[tier]->db_collection_handle = NULL;
-                            }
-                        }
-
-                        if (tiers_available == tiers_said_yes && tiers_said_yes) {
-                            /* This metric has no data and no references */
-                            delete_dimension_uuid(&rd->metric_uuid);
-                            rrddim_free(st, rd);
-                            if (unlikely(!last)) {
-                                rd = st->dimensions;
-                            }
-                            else {
-                                rd = last->next;
-                            }
-                            continue;
-                        }
-#ifdef ENABLE_ACLK
-                        else
-                            queue_dimension_to_aclk(rd, rd->last_collected_time.tv_sec);
-#endif
-                    }
-                    last = rd;
-                    rd = rd->next;
-                }
-                rrdset_unlock(st);
-
-                debug(D_RRD_CALLS, "RRDSET: Cleaning up remaining chart variables for host '%s', chart '%s'", host->hostname, st->id);
-                rrdvar_free_remaining_variables(host, &st->rrdvar_root_index);
-
-                rrdset_flag_clear(st, RRDSET_FLAG_OBSOLETE);
-                
-                if (st->dimensions) {
-                    /* If the chart still has dimensions don't delete it from the metadata log */
-                    continue;
-                }
-            }
-#endif
-            rrdset_rdlock(st);
-
-            if(rrdhost_delete_obsolete_charts)
-                rrdset_delete_files(st);
-            else
-                rrdset_save(st);
-
-            rrdset_unlock(st);
-
-            rrdset_free(st);
-            goto restart_after_removal;
-        }
-#ifdef ENABLE_ACLK
-        else
-            sql_check_chart_liveness(st);
-#endif
-    }
-}
-
-void rrdset_check_obsoletion(RRDHOST *host)
-{
-    RRDSET *st;
-    time_t last_entry_t;
-    rrdset_foreach_read(st, host) {
-        last_entry_t = rrdset_last_entry_t(st);
-        if (last_entry_t && last_entry_t < host->senders_connect_time) {
-            rrdset_is_obsolete(st);
-        }
-    }
-}
-
-void rrd_cleanup_obsolete_charts()
-{
-    rrd_rdlock();
-
-    RRDHOST *host;
-    rrdhost_foreach_read(host)
-    {
-        if (host->obsolete_charts_count) {
-            rrdhost_wrlock(host);
-            rrdhost_cleanup_obsolete_charts(host);
-            rrdhost_unlock(host);
-        }
-
-        if ( host != localhost &&
-             host->trigger_chart_obsoletion_check &&
-             ((host->senders_last_chart_command &&
-             host->senders_last_chart_command + host->health_delay_up_to < now_realtime_sec())
-              || (host->senders_connect_time + 300 < now_realtime_sec())) ) {
-            rrdhost_rdlock(host);
-            rrdset_check_obsoletion(host);
-            rrdhost_unlock(host);
-            host->trigger_chart_obsoletion_check = 0;
-        }
-    }
-
-    rrd_unlock();
-}
-
-// ----------------------------------------------------------------------------
 // RRDHOST - set system info from environment variables
 // system_info fields must be heap allocated or NULL
 int rrdhost_set_system_info_variable(struct rrdhost_system_info *system_info, char *name, char *value) {
@@ -1761,57 +1623,18 @@ int rrdhost_set_system_info_variable(struct rrdhost_system_info *system_info, ch
     return res;
 }
 
-/**
- * Alarm Compare ID
- *
- * Callback function used with the binary trees to compare the id of RRDCALC
- *
- * @param a a pointer to the RRDCAL item to insert,compare or update the binary tree
- * @param b the pointer to the binary tree.
- *
- * @return It returns 0 case the values are equal, 1 case a is bigger than b and -1 case a is smaller than b.
- */
-int alarm_compare_id(void *a, void *b) {
-    register uint32_t hash1 = ((RRDCALC *)a)->id;
-    register uint32_t hash2 = ((RRDCALC *)b)->id;
-
-    if(hash1 < hash2) return -1;
-    else if(hash1 > hash2) return 1;
-
-    return 0;
-}
-
-/**
- * Alarm Compare NAME
- *
- * Callback function used with the binary trees to compare the name of RRDCALC
- *
- * @param a a pointer to the RRDCAL item to insert,compare or update the binary tree
- * @param b the pointer to the binary tree.
- *
- * @return It returns 0 case the values are equal, 1 case a is bigger than b and -1 case a is smaller than b.
- */
-int alarm_compare_name(void *a, void *b) {
-    RRDCALC *in1 = (RRDCALC *)a;
-    RRDCALC *in2 = (RRDCALC *)b;
-
-    if(in1->hash < in2->hash) return -1;
-    else if(in1->hash > in2->hash) return 1;
-
-    return strcmp(in1->name,in2->name);
-}
-
 // Added for gap-filling, if this proves to be a bottleneck in large-scale systems then we will need to cache
 // the last entry times as the metric updates, but let's see if it is a problem first.
 time_t rrdhost_last_entry_t(RRDHOST *h) {
-    rrdhost_rdlock(h);
     RRDSET *st;
     time_t result = 0;
+
     rrdset_foreach_read(st, h) {
         time_t st_last = rrdset_last_entry_t(st);
+
         if (st_last > result)
             result = st_last;
     }
-    rrdhost_unlock(h);
+    rrdset_foreach_done(st);
     return result;
 }
diff --git a/database/rrdlabels.c b/database/rrdlabels.c
index 5198cb4aa..743499ab5 100644
--- a/database/rrdlabels.c
+++ b/database/rrdlabels.c
@@ -369,12 +369,15 @@ __attribute__((constructor)) void initialize_labels_keys_char_map(void) {
 
 }
 
-static size_t rrdlabels_sanitize(unsigned char *dst, const unsigned char *src, size_t dst_size, unsigned char *char_map, bool utf, const char *empty) {
+size_t text_sanitize(unsigned char *dst, const unsigned char *src, size_t dst_size, unsigned char *char_map, bool utf, const char *empty, size_t *multibyte_length) {
     if(unlikely(!dst_size)) return 0;
+
     if(unlikely(!src || !*src)) {
         strncpyz((char *)dst, empty, dst_size);
         dst[dst_size - 1] = '\0';
-        return strlen((char *)dst);
+        size_t len = strlen((char *)dst);
+        if(multibyte_length) *multibyte_length = len;
+        return len;
     }
 
     unsigned char *d = dst;
@@ -385,7 +388,9 @@ static size_t rrdlabels_sanitize(unsigned char *dst, const unsigned char *src, s
     // copy while converting, but keep only one white space
     // we start wil last_is_space = 1 to skip leading spaces
     int last_is_space = 1;
+
     size_t mblen = 0;
+
     while(*src && d < end) {
         unsigned char c = *src;
 
@@ -446,28 +451,34 @@ static size_t rrdlabels_sanitize(unsigned char *dst, const unsigned char *src, s
     *d = '\0';
 
     // check if dst is all underscores and empty it if it is
-    d = dst;
-    while(*d == '_') d++;
-    if(unlikely(*d == '\0')) {
-        *dst = '\0';
-        mblen = 0;
+    if(*dst == '_') {
+        unsigned char *t = dst;
+        while (*t == '_') t++;
+        if (unlikely(*t == '\0')) {
+            *dst = '\0';
+            mblen = 0;
+        }
     }
 
     if(unlikely(*dst == '\0')) {
         strncpyz((char *)dst, empty, dst_size);
         dst[dst_size - 1] = '\0';
-        return strlen((char *)dst);
+        mblen = strlen((char *)dst);
+        if(multibyte_length) *multibyte_length = mblen;
+        return mblen;
     }
 
-    return mblen;
+    if(multibyte_length) *multibyte_length = mblen;
+
+    return d - dst;
 }
 
 static inline size_t rrdlabels_sanitize_name(char *dst, const char *src, size_t dst_size) {
-    return rrdlabels_sanitize((unsigned char *)dst, (const unsigned char *)src, dst_size, label_names_char_map, 0, "");
+    return text_sanitize((unsigned char *)dst, (const unsigned char *)src, dst_size, label_names_char_map, 0, "", NULL);
 }
 
 static inline size_t rrdlabels_sanitize_value(char *dst, const char *src, size_t dst_size) {
-    return rrdlabels_sanitize((unsigned char *)dst, (const unsigned char *)src, dst_size, label_values_char_map, 1, "[none]");
+    return text_sanitize((unsigned char *)dst, (const unsigned char *)src, dst_size, label_values_char_map, 1, "[none]", NULL);
 }
 
 // ----------------------------------------------------------------------------
@@ -478,9 +489,7 @@ typedef struct rrdlabel {
     RRDLABEL_SRC label_source;
 } RRDLABEL;
 
-static void rrdlabel_insert_callback(const char *name, void *value, void *data) {
-    (void)name;
-    DICTIONARY *dict = (DICTIONARY *)data; (void)dict;
+static void rrdlabel_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *dict_ptr __maybe_unused) {
     RRDLABEL *lb = (RRDLABEL *)value;
 
     // label_value is already allocated by the STRING
@@ -488,42 +497,43 @@ static void rrdlabel_insert_callback(const char *name, void *value, void *data)
     lb->label_source &= ~RRDLABEL_FLAG_OLD;
 }
 
-static void rrdlabel_delete_callback(const char *name, void *value, void *data) {
-    (void)name;
-    DICTIONARY *dict = (DICTIONARY *)data; (void)dict;
+static void rrdlabel_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *dict_ptr __maybe_unused) {
     RRDLABEL *lb = (RRDLABEL *)value;
 
     string_freez(lb->label_value);
     lb->label_value = NULL;
 }
 
-static void rrdlabel_conflict_callback(const char *name, void *oldvalue, void *newvalue, void *data) {
-    (void)name;
-    DICTIONARY *dict = (DICTIONARY *)data; (void)dict;
+static bool rrdlabel_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *oldvalue, void *newvalue, void *dict_ptr __maybe_unused) {
     RRDLABEL *lbold = (RRDLABEL *)oldvalue;
     RRDLABEL *lbnew = (RRDLABEL *)newvalue;
 
-    if(lbold->label_value == lbnew->label_value || strcmp(string2str(lbold->label_value), string2str(lbnew->label_value)) == 0) {
+    if(lbold->label_value == lbnew->label_value) {
         // they are the same
+
         lbold->label_source |=  lbnew->label_source;
         lbold->label_source |=  RRDLABEL_FLAG_OLD;
         lbold->label_source &= ~RRDLABEL_FLAG_NEW;
 
         // free the new one
         string_freez(lbnew->label_value);
+
+        return false;
     }
-    else {
-        // they are different
-        string_freez(lbold->label_value);
-        lbold->label_value  =   lbnew->label_value;
-        lbold->label_source =   lbnew->label_source;
-        lbold->label_source |=  RRDLABEL_FLAG_NEW;
-        lbold->label_source &= ~RRDLABEL_FLAG_OLD;
-    }
+
+    // they are different
+
+    string_freez(lbold->label_value);
+    lbold->label_value  =   lbnew->label_value;
+    lbold->label_source =   lbnew->label_source;
+    lbold->label_source |=  RRDLABEL_FLAG_NEW;
+    lbold->label_source &= ~RRDLABEL_FLAG_OLD;
+
+    return true;
 }
 
 DICTIONARY *rrdlabels_create(void) {
-    DICTIONARY *dict = dictionary_create(DICTIONARY_FLAG_DONT_OVERWRITE_VALUE);
+    DICTIONARY *dict = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
     dictionary_register_insert_callback(dict, rrdlabel_insert_callback, dict);
     dictionary_register_delete_callback(dict, rrdlabel_delete_callback, dict);
     dictionary_register_conflict_callback(dict, rrdlabel_conflict_callback, dict);
@@ -538,6 +548,9 @@ void rrdlabels_destroy(DICTIONARY *labels_dict) {
     dictionary_destroy(labels_dict);
 }
 
+void rrdlabels_flush(DICTIONARY *labels_dict) {
+    dictionary_flush(labels_dict);
+}
 
 // ----------------------------------------------------------------------------
 // rrdlabels_add()
@@ -620,10 +633,12 @@ void rrdlabels_add_pair(DICTIONARY *dict, const char *string, RRDLABEL_SRC ls) {
 }
 
 // ----------------------------------------------------------------------------
-// rrdlabels_get_to_buffer_or_null()
+// rrdlabels_get_value_to_buffer_or_null()
 
 void rrdlabels_get_value_to_buffer_or_null(DICTIONARY *labels, BUFFER *wb, const char *key, const char *quote, const char *null) {
-    DICTIONARY_ITEM *acquired_item = dictionary_get_and_acquire_item(labels, key);
+    if(!labels) return;
+
+    const DICTIONARY_ITEM *acquired_item = dictionary_get_and_acquire_item(labels, key);
     RRDLABEL *lb = dictionary_acquired_item_value(acquired_item);
 
     if(lb && lb->label_value)
@@ -634,15 +649,23 @@ void rrdlabels_get_value_to_buffer_or_null(DICTIONARY *labels, BUFFER *wb, const
     dictionary_acquired_item_release(labels, acquired_item);
 }
 
+// ----------------------------------------------------------------------------
+// rrdlabels_get_value_to_char_or_null()
+
+void rrdlabels_get_value_to_char_or_null(DICTIONARY *labels, char **value, const char *key) {
+    const DICTIONARY_ITEM *acquired_item = dictionary_get_and_acquire_item(labels, key);
+    RRDLABEL *lb = dictionary_acquired_item_value(acquired_item);
+
+    *value = (lb && lb->label_value) ? strdupz(string2str(lb->label_value)) : NULL;
+
+    dictionary_acquired_item_release(labels, acquired_item);
+}
 
 // ----------------------------------------------------------------------------
 // rrdlabels_unmark_all()
 // remove labels RRDLABEL_FLAG_OLD and RRDLABEL_FLAG_NEW from all dictionary items
 
-static int remove_flags_old_new(const char *name, void *value, void *data) {
-    (void)name;
-    (void)data;
-
+static int remove_flags_old_new(const DICTIONARY_ITEM *item __maybe_unused, void *value, void *data __maybe_unused) {
     RRDLABEL *lb = (RRDLABEL *)value;
 
     if(lb->label_source & RRDLABEL_FLAG_OLD) lb->label_source &= ~RRDLABEL_FLAG_OLD;
@@ -660,12 +683,13 @@ void rrdlabels_unmark_all(DICTIONARY *labels) {
 // rrdlabels_remove_all_unmarked()
 // remove dictionary items that are neither old, nor new
 
-static int remove_not_old_not_new_callback(const char *name, void *value, void *data) {
+static int remove_not_old_not_new_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *name = dictionary_acquired_item_name(item);
     DICTIONARY *dict = (DICTIONARY *)data;
     RRDLABEL *lb = (RRDLABEL *)value;
 
     if(!(lb->label_source & (RRDLABEL_FLAG_OLD | RRDLABEL_FLAG_NEW | RRDLABEL_FLAG_PERMANENT))) {
-        dictionary_del_having_write_lock(dict, name);
+        dictionary_del(dict, name);
         return 1;
     }
 
@@ -685,7 +709,8 @@ struct labels_walkthrough {
     void *data;
 };
 
-static int labels_walkthrough_callback(const char *name, void *value, void *data) {
+static int labels_walkthrough_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *name = dictionary_acquired_item_name(item);
     struct labels_walkthrough *d = (struct labels_walkthrough *)data;
     RRDLABEL *lb = (RRDLABEL *)value;
 
@@ -717,7 +742,8 @@ int rrdlabels_sorted_walkthrough_read(DICTIONARY *labels, int (*callback)(const
 // rrdlabels_migrate_to_these()
 // migrate an existing label list to a new list, INPLACE
 
-static int copy_label_to_dictionary_callback(const char *name, void *value, void *data) {
+static int copy_label_to_dictionary_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *name = dictionary_acquired_item_name(item);
     DICTIONARY *dst = (DICTIONARY *)data;
     RRDLABEL *lb = (RRDLABEL *)value;
     labels_add_already_sanitized(dst, name, string2str(lb->label_value), lb->label_source);
@@ -754,7 +780,8 @@ struct simple_pattern_match_name_value {
     char equal;
 };
 
-static int simple_pattern_match_name_only_callback(const char *name, void *value, void *data) {
+static int simple_pattern_match_name_only_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *name = dictionary_acquired_item_name(item);
     struct simple_pattern_match_name_value *t = (struct simple_pattern_match_name_value *)data;
     (void)value;
 
@@ -764,7 +791,8 @@ static int simple_pattern_match_name_only_callback(const char *name, void *value
     return 0;
 }
 
-static int simple_pattern_match_name_and_value_callback(const char *name, void *value, void *data) {
+static int simple_pattern_match_name_and_value_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *name = dictionary_acquired_item_name(item);
     struct simple_pattern_match_name_value *t = (struct simple_pattern_match_name_value *)data;
     RRDLABEL *lb = (RRDLABEL *)value;
 
@@ -830,7 +858,9 @@ bool rrdlabels_match_simple_pattern(DICTIONARY *labels, const char *simple_patte
 // ----------------------------------------------------------------------------
 // Log all labels
 
-static int rrdlabels_log_label_to_buffer_callback(const char *name, void *value, void *data) {
+static int rrdlabels_log_label_to_buffer_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *name = dictionary_acquired_item_name(item);
+
     BUFFER *wb = (BUFFER *)data;
     RRDLABEL *lb = (RRDLABEL *)value;
 
@@ -880,7 +910,8 @@ struct labels_to_buffer {
     size_t count;
 };
 
-static int label_to_buffer_callback(const char *name, void *value, void *data) {
+static int label_to_buffer_callback(const DICTIONARY_ITEM *item, void *value, void *data) {
+    const char *name = dictionary_acquired_item_name(item);
     struct labels_to_buffer *t = (struct labels_to_buffer *)data;
     RRDLABEL *lb = (RRDLABEL *)value;
 
@@ -926,23 +957,17 @@ int rrdlabels_to_buffer(DICTIONARY *labels, BUFFER *wb, const char *before_each,
     return dictionary_walkthrough_read(labels, label_to_buffer_callback, (void *)&tmp);
 }
 
-static int chart_label_store_to_sql_callback(const char *name, const char *value, RRDLABEL_SRC ls, void *data) {
-    RRDSET *st = (RRDSET *)data;
-    sql_store_chart_label(st->chart_uuid, (int)ls, (char *)name, (char *)value);
-    return 1;
-}
-
 void rrdset_update_rrdlabels(RRDSET *st, DICTIONARY *new_rrdlabels) {
-    if(!st->state->chart_labels)
-        st->state->chart_labels = rrdlabels_create();
+    if(!st->rrdlabels)
+        st->rrdlabels = rrdlabels_create();
 
     if (new_rrdlabels)
-        rrdlabels_migrate_to_these(st->state->chart_labels, new_rrdlabels);
+        rrdlabels_migrate_to_these(st->rrdlabels, new_rrdlabels);
 
-    // TODO - we should also cleanup sqlite from old new_rrdlabels that have been removed
-    rrdlabels_walkthrough_read(st->state->chart_labels, chart_label_store_to_sql_callback, st);
+    metaqueue_chart_labels(st);
 }
 
+
 // ----------------------------------------------------------------------------
 // rrdlabels unit test
 
@@ -1107,12 +1132,14 @@ int rrdlabels_unittest_simple_pattern() {
 
 int rrdlabels_unittest_sanitize_value(const char *src, const char *expected) {
     char buf[RRDLABELS_MAX_VALUE_LENGTH + 1];
-    size_t mblen = rrdlabels_sanitize_value(buf, src, RRDLABELS_MAX_VALUE_LENGTH);
+    size_t len = rrdlabels_sanitize_value(buf, src, RRDLABELS_MAX_VALUE_LENGTH);
+    size_t expected_len = strlen(expected);
 
     int err = 0;
     if(strcmp(buf, expected) != 0) err = 1;
+    if(len != expected_len) err = 1;
 
-    fprintf(stderr, "%s(%s): %s, expected '%s', got '%s', mblen = %zu, bytes = %zu\n", __FUNCTION__, src, (err==1)?"FAILED":"OK", expected, buf, mblen, strlen(buf));
+    fprintf(stderr, "%s(%s): %s, expected '%s', got '%s', expected bytes = %zu, got bytes = %zu\n", __FUNCTION__, src, (err==1)?"FAILED":"OK", expected, buf, expected_len, strlen(buf));
     return err;
 }
 
diff --git a/database/rrdset.c b/database/rrdset.c
index 9693ee211..6eb3c7105 100644
--- a/database/rrdset.c
+++ b/database/rrdset.c
@@ -3,97 +3,452 @@
 #define NETDATA_RRD_INTERNALS
 #include "rrd.h"
 #include <sched.h>
+#include "storage_engine.h"
 
-void __rrdset_check_rdlock(RRDSET *st, const char *file, const char *function, const unsigned long line) {
-    debug(D_RRD_CALLS, "Checking read lock on chart '%s'", st->id);
+// ----------------------------------------------------------------------------
+// RRDSET name index
 
-    int ret = netdata_rwlock_trywrlock(&st->rrdset_rwlock);
-    if(ret == 0)
-        fatal("RRDSET '%s' should be read-locked, but it is not, at function %s() at line %lu of file '%s'", st->id, function, line, file);
+static void rrdset_name_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdset, void *rrdhost __maybe_unused) {
+    RRDSET *st = rrdset;
+    rrdset_flag_set(st, RRDSET_FLAG_INDEXED_NAME);
+}
+static void rrdset_name_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdset, void *rrdhost __maybe_unused) {
+    RRDSET *st = rrdset;
+    rrdset_flag_clear(st, RRDSET_FLAG_INDEXED_NAME);
 }
 
-void __rrdset_check_wrlock(RRDSET *st, const char *file, const char *function, const unsigned long line) {
-    debug(D_RRD_CALLS, "Checking write lock on chart '%s'", st->id);
+static inline void rrdset_index_add_name(RRDHOST *host, RRDSET *st) {
+    if(!st->name) return;
+    dictionary_set(host->rrdset_root_index_name, rrdset_name(st), st, sizeof(RRDSET));
+}
 
-    int ret = netdata_rwlock_tryrdlock(&st->rrdset_rwlock);
-    if(ret == 0)
-        fatal("RRDSET '%s' should be write-locked, but it is not, at function %s() at line %lu of file '%s'", st->id, function, line, file);
+static inline void rrdset_index_del_name(RRDHOST *host, RRDSET *st) {
+    if(rrdset_flag_check(st, RRDSET_FLAG_INDEXED_NAME))
+        dictionary_del(host->rrdset_root_index_name, rrdset_name(st));
 }
 
+static inline RRDSET *rrdset_index_find_name(RRDHOST *host, const char *name) {
+    return dictionary_get(host->rrdset_root_index_name, name);
+}
 
 // ----------------------------------------------------------------------------
 // RRDSET index
 
-int rrdset_compare(void* a, void* b) {
-    if(((RRDSET *)a)->hash < ((RRDSET *)b)->hash) return -1;
-    else if(((RRDSET *)a)->hash > ((RRDSET *)b)->hash) return 1;
-    else return strcmp(((RRDSET *)a)->id, ((RRDSET *)b)->id);
+static inline void rrdset_update_permanent_labels(RRDSET *st) {
+    if(!st->rrdlabels) return;
+
+    rrdlabels_add(st->rrdlabels, "_collect_plugin", rrdset_plugin_name(st), RRDLABEL_SRC_AUTO| RRDLABEL_FLAG_PERMANENT);
+    rrdlabels_add(st->rrdlabels, "_collect_module", rrdset_module_name(st), RRDLABEL_SRC_AUTO| RRDLABEL_FLAG_PERMANENT);
 }
 
-static RRDSET *rrdset_index_find(RRDHOST *host, const char *id, uint32_t hash) {
-    RRDSET tmp;
-    strncpyz(tmp.id, id, RRD_ID_LENGTH_MAX);
-    tmp.hash = (hash)?hash:simple_hash(tmp.id);
+static STRING *rrdset_fix_name(RRDHOST *host, const char *chart_full_id, const char *type, const char *current_name, const char *name) {
+    if(!name || !*name) return NULL;
+
+    char full_name[RRD_ID_LENGTH_MAX + 1];
+    char sanitized_name[CONFIG_MAX_VALUE + 1];
+    char new_name[CONFIG_MAX_VALUE + 1];
+
+    snprintfz(full_name, RRD_ID_LENGTH_MAX, "%s.%s", type, name);
+    rrdset_strncpyz_name(sanitized_name, full_name, CONFIG_MAX_VALUE);
+    strncpyz(new_name, sanitized_name, CONFIG_MAX_VALUE);
+
+    if(rrdset_index_find_name(host, new_name)) {
+        debug(D_RRD_CALLS, "RRDSET: chart name '%s' on host '%s' already exists.", new_name, rrdhost_hostname(host));
+        if(!strcmp(chart_full_id, full_name) && (!current_name || !*current_name)) {
+            unsigned i = 1;
+
+            do {
+                snprintfz(new_name, CONFIG_MAX_VALUE, "%s_%u", sanitized_name, i);
+                i++;
+            } while (rrdset_index_find_name(host, new_name));
 
-    return (RRDSET *)avl_search_lock(&(host->rrdset_root_index), (avl_t *) &tmp);
+            info("RRDSET: using name '%s' for chart '%s' on host '%s'.", new_name, full_name, rrdhost_hostname(host));
+        }
+        else
+            return NULL;
+    }
+
+    return string_strdupz(new_name);
 }
 
-// ----------------------------------------------------------------------------
-// RRDSET name index
+struct rrdset_constructor {
+    RRDHOST *host;
+    const char *type;
+    const char *id;
+    const char *name;
+    const char *family;
+    const char *context;
+    const char *title;
+    const char *units;
+    const char *plugin;
+    const char *module;
+    long priority;
+    int update_every;
+    RRDSET_TYPE chart_type;
+    RRD_MEMORY_MODE memory_mode;
+    long history_entries;
+
+    enum {
+        RRDSET_REACT_NONE                   = 0,
+        RRDSET_REACT_NEW                    = (1 << 0),
+        RRDSET_REACT_UPDATED                = (1 << 1),
+        RRDSET_REACT_PLUGIN_UPDATED         = (1 << 2),
+        RRDSET_REACT_MODULE_UPDATED         = (1 << 3),
+        RRDSET_REACT_CHART_ACTIVATED        = (1 << 4),
+    } react_action;
+};
+
+// the constructor - the dictionary is write locked while this runs
+static void rrdset_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdset, void *constructor_data) {
+    struct rrdset_constructor *ctr = constructor_data;
+    RRDHOST *host = ctr->host;
+    RRDSET *st = rrdset;
+
+    const char *chart_full_id = dictionary_acquired_item_name(item);
+
+    st->id = string_strdupz(chart_full_id);
+
+    st->name = rrdset_fix_name(host, chart_full_id, ctr->type, NULL, ctr->name);
+    if(!st->name)
+        st->name = rrdset_fix_name(host, chart_full_id, ctr->type, NULL, ctr->id);
+    rrdset_index_add_name(host, st);
+
+    st->parts.id = string_strdupz(ctr->id);
+    st->parts.type = string_strdupz(ctr->type);
+    st->parts.name = string_strdupz(ctr->name);
+
+    st->family = (ctr->family && *ctr->family) ? rrd_string_strdupz(ctr->family) : rrd_string_strdupz(ctr->type);
+    st->context = (ctr->context && *ctr->context) ? rrd_string_strdupz(ctr->context) : rrd_string_strdupz(chart_full_id);
+
+    st->units = rrd_string_strdupz(ctr->units);
+    st->title = rrd_string_strdupz(ctr->title);
+    st->plugin_name = rrd_string_strdupz(ctr->plugin);
+    st->module_name = rrd_string_strdupz(ctr->module);
+    st->priority = ctr->priority;
 
-#define rrdset_from_avlname(avlname_ptr) ((RRDSET *)((avlname_ptr) - offsetof(RRDSET, avlname)))
+    st->cache_dir = rrdset_cache_dir(host, chart_full_id);
+    st->entries = (ctr->memory_mode != RRD_MEMORY_MODE_DBENGINE) ? align_entries_to_pagesize(ctr->memory_mode, ctr->history_entries) : 5;
+    st->update_every = ctr->update_every;
+    st->rrd_memory_mode = ctr->memory_mode;
 
-int rrdset_compare_name(void* a, void* b) {
-    RRDSET *A = rrdset_from_avlname(a);
-    RRDSET *B = rrdset_from_avlname(b);
+    st->chart_type = ctr->chart_type;
+    st->gap_when_lost_iterations_above = (int) (gap_when_lost_iterations_above + 2);
+    st->rrdhost = host;
+
+    st->flags =   RRDSET_FLAG_SYNC_CLOCK
+                | RRDSET_FLAG_INDEXED_ID
+                | RRDSET_FLAG_RECEIVER_REPLICATION_FINISHED
+                | RRDSET_FLAG_SENDER_REPLICATION_FINISHED
+                ;
+
+    netdata_rwlock_init(&st->alerts.rwlock);
+
+    if(st->rrd_memory_mode == RRD_MEMORY_MODE_SAVE || st->rrd_memory_mode == RRD_MEMORY_MODE_MAP) {
+        if(!rrdset_memory_load_or_create_map_save(st, st->rrd_memory_mode)) {
+            info("Failed to use db mode %s for chart '%s', falling back to ram mode.", (st->rrd_memory_mode == RRD_MEMORY_MODE_MAP)?"map":"save", rrdset_name(st));
+            st->rrd_memory_mode = RRD_MEMORY_MODE_RAM;
+        }
+    }
+
+    // initialize the db tiers
+    {
+        for(size_t tier = 0; tier < storage_tiers ; tier++) {
+            STORAGE_ENGINE *eng = st->rrdhost->db[tier].eng;
+            if(!eng) continue;
+
+            st->storage_metrics_groups[tier] = eng->api.collect_ops.metrics_group_get(host->db[tier].instance, &st->chart_uuid);
+        }
+    }
+
+    rrddim_index_init(st);
+
+    // chart variables - we need this for data collection to work (collector given chart variables) - not only health
+    rrdsetvar_index_init(st);
+
+    if (host->health_enabled) {
+        st->rrdfamily = rrdfamily_add_and_acquire(host, rrdset_family(st));
+        st->rrdvars = rrdvariables_create();
+        rrddimvar_index_init(st);
+    }
+
+    st->rrdlabels = rrdlabels_create();
+    rrdset_update_permanent_labels(st);
 
-    // fprintf(stderr, "COMPARING: %s with %s\n", A->name, B->name);
+    st->green = NAN;
+    st->red = NAN;
 
-    if(A->hash_name < B->hash_name) return -1;
-    else if(A->hash_name > B->hash_name) return 1;
-    else return strcmp(A->name, B->name);
+    ctr->react_action = RRDSET_REACT_NEW;
 }
 
-RRDSET *rrdset_index_add_name(RRDHOST *host, RRDSET *st) {
-    void *result;
-    // fprintf(stderr, "ADDING: %s (name: %s)\n", st->id, st->name);
-    result = avl_insert_lock(&host->rrdset_root_index_name, (avl_t *) (&st->avlname));
-    if(result) return rrdset_from_avlname(result);
-    return NULL;
+// the destructor - the dictionary is write locked while this runs
+static void rrdset_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdset, void *rrdhost) {
+    RRDHOST *host = rrdhost;
+    RRDSET *st = rrdset;
+
+    rrdset_flag_clear(st, RRDSET_FLAG_INDEXED_ID);
+
+    // cleanup storage engines
+    {
+        for(size_t tier = 0; tier < storage_tiers ; tier++) {
+            STORAGE_ENGINE *eng = st->rrdhost->db[tier].eng;
+            if(!eng) continue;
+
+            eng->api.collect_ops.metrics_group_release(host->db[tier].instance, st->storage_metrics_groups[tier]);
+        }
+    }
+
+    // remove it from the name index
+    rrdset_index_del_name(host, st);
+
+    // release the collector info
+    dictionary_destroy(st->functions_view);
+
+    rrdcalc_unlink_all_rrdset_alerts(st);
+
+    // ------------------------------------------------------------------------
+    // the order of destruction is important here
+
+    // 1. delete RRDDIMVAR index - this will speed up the destruction of RRDDIMs
+    //    because each dimension loops to find its own variables in this index.
+    //    There are no references to the items on this index from the dimensions.
+    //    To find their own, they have to walk-through the dictionary.
+    rrddimvar_index_destroy(st);                // destroy the rrddimvar index
+
+    // 2. delete RRDSETVAR index
+    rrdsetvar_index_destroy(st);                // destroy the rrdsetvar index
+
+    // 3. delete RRDVAR index after the above, to avoid triggering its garbage collector (they have references on this)
+    rrdvariables_destroy(st->rrdvars);      // free all variables and destroy the rrdvar dictionary
+
+    // 4. delete RRDFAMILY - this has to be last, because RRDDIMVAR and RRDSETVAR need the reference counter
+    rrdfamily_release(host, st->rrdfamily); // release the acquired rrdfamily -- has to be after all variables
+
+    // 5. delete RRDDIMs, now their variables are not existing, so this is fast
+    rrddim_index_destroy(st);                   // free all the dimensions and destroy the dimensions index
+
+    // 6. this has to be after the dimensions are freed, but before labels are freed (contexts need the labels)
+    rrdcontext_removed_rrdset(st);              // let contexts know
+
+    // 7. destroy the chart labels
+    rrdlabels_destroy(st->rrdlabels);  // destroy the labels, after letting the contexts know
+
+    rrdset_memory_file_free(st);                // remove files of db mode save and map
+
+    // ------------------------------------------------------------------------
+    // free it
+
+    netdata_rwlock_destroy(&st->alerts.rwlock);
+
+    string_freez(st->id);
+    string_freez(st->name);
+    string_freez(st->parts.id);
+    string_freez(st->parts.type);
+    string_freez(st->parts.name);
+    string_freez(st->family);
+    string_freez(st->title);
+    string_freez(st->units);
+    string_freez(st->context);
+    string_freez(st->plugin_name);
+    string_freez(st->module_name);
+
+    freez(st->exporting_flags);
+    freez(st->cache_dir);
 }
 
-RRDSET *rrdset_index_del_name(RRDHOST *host, RRDSET *st) {
-    void *result;
-    // fprintf(stderr, "DELETING: %s (name: %s)\n", st->id, st->name);
-    result = (RRDSET *)avl_remove_lock(&((host)->rrdset_root_index_name), (avl_t *)(&st->avlname));
-    if(result) return rrdset_from_avlname(result);
-    return NULL;
+// the item to be inserted, is already in the dictionary
+// this callback deals with the situation, migrating the existing object to the new values
+// the dictionary is write locked while this runs
+static bool rrdset_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdset, void *new_rrdset, void *constructor_data) {
+    (void)new_rrdset; // it is NULL
+
+    struct rrdset_constructor *ctr = constructor_data;
+    RRDSET *st = rrdset;
+
+    rrdset_isnot_obsolete(st);
+
+    ctr->react_action = RRDSET_REACT_NONE;
+
+    if (rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED)) {
+        rrdset_flag_clear(st, RRDSET_FLAG_ARCHIVED);
+        ctr->react_action |= RRDSET_REACT_CHART_ACTIVATED;
+    }
+
+    if (rrdset_reset_name(st, (ctr->name && *ctr->name) ? ctr->name : ctr->id) == 2)
+        ctr->react_action |= RRDSET_REACT_UPDATED;
+
+    if (unlikely(st->priority != ctr->priority)) {
+        st->priority = ctr->priority;
+        ctr->react_action |= RRDSET_REACT_UPDATED;
+    }
+
+    if (unlikely(st->update_every != ctr->update_every)) {
+        rrdset_set_update_every(st, ctr->update_every);
+        ctr->react_action |= RRDSET_REACT_UPDATED;
+    }
+
+    if(ctr->plugin && *ctr->plugin) {
+        STRING *old_plugin = st->plugin_name;
+        st->plugin_name = rrd_string_strdupz(ctr->plugin);
+        if (old_plugin != st->plugin_name)
+            ctr->react_action |= RRDSET_REACT_PLUGIN_UPDATED;
+        string_freez(old_plugin);
+    }
+
+    if(ctr->module && *ctr->module) {
+        STRING *old_module = st->module_name;
+        st->module_name = rrd_string_strdupz(ctr->module);
+        if (old_module != st->module_name)
+            ctr->react_action |= RRDSET_REACT_MODULE_UPDATED;
+        string_freez(old_module);
+    }
+
+    if(ctr->title && *ctr->title) {
+        STRING *old_title = st->title;
+        st->title = rrd_string_strdupz(ctr->title);
+        if(old_title != st->title)
+            ctr->react_action |= RRDSET_REACT_UPDATED;
+        string_freez(old_title);
+    }
+
+    if(ctr->units && *ctr->units) {
+        STRING *old_units = st->units;
+        st->units = rrd_string_strdupz(ctr->units);
+        if(old_units != st->units)
+            ctr->react_action |= RRDSET_REACT_UPDATED;
+        string_freez(old_units);
+    }
+
+    if(ctr->family && *ctr->family) {
+        STRING *old_family = st->family;
+        st->family = rrd_string_strdupz(ctr->family);
+        if(old_family != st->family)
+            ctr->react_action |= RRDSET_REACT_UPDATED;
+        string_freez(old_family);
+
+        // TODO - we should rename RRDFAMILY variables
+    }
+
+    if(ctr->context && *ctr->context) {
+        STRING *old_context = st->context;
+        st->context = rrd_string_strdupz(ctr->context);
+        if(old_context != st->context)
+            ctr->react_action |= RRDSET_REACT_UPDATED;
+        string_freez(old_context);
+    }
+
+    if(st->chart_type != ctr->chart_type) {
+        st->chart_type = ctr->chart_type;
+        ctr->react_action |= RRDSET_REACT_UPDATED;
+    }
+
+    rrdset_update_permanent_labels(st);
+
+    rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
+    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
+
+    return ctr->react_action != RRDSET_REACT_NONE;
 }
 
+// this is called after all insertions/conflicts, with the dictionary unlocked, with a reference to RRDSET
+// so, any actions requiring locks on other objects, should be placed here
+static void rrdset_react_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdset, void *constructor_data) {
+    struct rrdset_constructor *ctr = constructor_data;
+    RRDSET *st = rrdset;
+    RRDHOST *host = st->rrdhost;
 
-// ----------------------------------------------------------------------------
-// RRDSET - find charts
+    st->last_accessed_time = now_realtime_sec();
+
+    if(host->health_enabled && (ctr->react_action & (RRDSET_REACT_NEW | RRDSET_REACT_CHART_ACTIVATED))) {
+        rrdset_flag_set(st, RRDSET_FLAG_PENDING_HEALTH_INITIALIZATION);
+        rrdhost_flag_set(st->rrdhost, RRDHOST_FLAG_PENDING_HEALTH_INITIALIZATION);
+    }
+
+    if(ctr->react_action & (RRDSET_REACT_NEW | RRDSET_REACT_PLUGIN_UPDATED | RRDSET_REACT_MODULE_UPDATED)) {
+        if (ctr->react_action & RRDSET_REACT_NEW) {
+            if(unlikely(rrdcontext_find_chart_uuid(st,  &st->chart_uuid))) {
+                uuid_generate(st->chart_uuid);
+                bool found_in_sql = false; (void)found_in_sql;
+
+//                bool found_in_sql = true;
+//                if(unlikely(sql_find_chart_uuid(host, st, &st->chart_uuid))) {
+//                    uuid_generate(st->chart_uuid);
+//                    found_in_sql = false;
+//                }
+
+#ifdef NETDATA_INTERNAL_CHECKS
+                char uuid_str[UUID_STR_LEN];
+                uuid_unparse_lower(st->chart_uuid, uuid_str);
+                error_report("Chart UUID for host %s chart [%s] not found in context. It is now set to %s (%s)",
+                             string2str(host->hostname),
+                             string2str(st->name), uuid_str, found_in_sql ? "found in sqlite" : "newly generated");
+#endif
+            }
+        }
+        rrdset_flag_set(st, RRDSET_FLAG_METADATA_UPDATE);
+        rrdhost_flag_set(st->rrdhost, RRDHOST_FLAG_METADATA_UPDATE);
+    }
+
+    rrdcontext_updated_rrdset(st);
+}
+
+void rrdset_index_init(RRDHOST *host) {
+    if(!host->rrdset_root_index) {
+        host->rrdset_root_index = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
+
+        dictionary_register_insert_callback(host->rrdset_root_index, rrdset_insert_callback, NULL);
+        dictionary_register_conflict_callback(host->rrdset_root_index, rrdset_conflict_callback, NULL);
+        dictionary_register_react_callback(host->rrdset_root_index, rrdset_react_callback, NULL);
+        dictionary_register_delete_callback(host->rrdset_root_index, rrdset_delete_callback, host);
+    }
+
+    if(!host->rrdset_root_index_name) {
+        host->rrdset_root_index_name = dictionary_create(
+            DICT_OPTION_NAME_LINK_DONT_CLONE | DICT_OPTION_VALUE_LINK_DONT_CLONE | DICT_OPTION_DONT_OVERWRITE_VALUE);
+
+        dictionary_register_insert_callback(host->rrdset_root_index_name, rrdset_name_insert_callback, host);
+        dictionary_register_delete_callback(host->rrdset_root_index_name, rrdset_name_delete_callback, host);
+    }
+}
 
-static inline RRDSET *rrdset_index_find_name(RRDHOST *host, const char *name, uint32_t hash) {
-    void *result = NULL;
-    RRDSET tmp;
-    tmp.name = name;
-    tmp.hash_name = (hash)?hash:simple_hash(tmp.name);
+void rrdset_index_destroy(RRDHOST *host) {
+    // destroy the name index first
+    dictionary_destroy(host->rrdset_root_index_name);
+    host->rrdset_root_index_name = NULL;
 
-    result = avl_search_lock(&host->rrdset_root_index_name, (avl_t *) (&(tmp.avlname)));
-    if(result) return rrdset_from_avlname(result);
+    // destroy the id index last
+    dictionary_destroy(host->rrdset_root_index);
+    host->rrdset_root_index = NULL;
+}
+
+static inline RRDSET *rrdset_index_add(RRDHOST *host, const char *id, struct rrdset_constructor *st_ctr) {
+    return dictionary_set_advanced(host->rrdset_root_index, id, -1, NULL, sizeof(RRDSET), st_ctr);
+}
+
+static inline void rrdset_index_del(RRDHOST *host, RRDSET *st) {
+    if(rrdset_flag_check(st, RRDSET_FLAG_INDEXED_ID))
+        dictionary_del(host->rrdset_root_index, rrdset_id(st));
+}
 
-    return NULL;
+static RRDSET *rrdset_index_find(RRDHOST *host, const char *id) {
+    // TODO - the name index should have an acquired dictionary item, not just a pointer to RRDSET
+    return dictionary_get(host->rrdset_root_index, id);
 }
 
+// ----------------------------------------------------------------------------
+// RRDSET - find charts
+
 inline RRDSET *rrdset_find(RRDHOST *host, const char *id) {
-    debug(D_RRD_CALLS, "rrdset_find() for chart '%s' in host '%s'", id, host->hostname);
-    RRDSET *st = rrdset_index_find(host, id, 0);
+    debug(D_RRD_CALLS, "rrdset_find() for chart '%s' in host '%s'", id, rrdhost_hostname(host));
+    RRDSET *st = rrdset_index_find(host, id);
+
+    if(st)
+        st->last_accessed_time = now_realtime_sec();
+
     return(st);
 }
 
 inline RRDSET *rrdset_find_bytype(RRDHOST *host, const char *type, const char *id) {
-    debug(D_RRD_CALLS, "rrdset_find_bytype() for chart '%s.%s' in host '%s'", type, id, host->hostname);
+    debug(D_RRD_CALLS, "rrdset_find_bytype() for chart '%s.%s' in host '%s'", type, id, rrdhost_hostname(host));
 
     char buf[RRD_ID_LENGTH_MAX + 1];
     strncpyz(buf, type, RRD_ID_LENGTH_MAX - 1);
@@ -105,8 +460,8 @@ inline RRDSET *rrdset_find_bytype(RRDHOST *host, const char *type, const char *i
 }
 
 inline RRDSET *rrdset_find_byname(RRDHOST *host, const char *name) {
-    debug(D_RRD_CALLS, "rrdset_find_byname() for chart '%s' in host '%s'", name, host->hostname);
-    RRDSET *st = rrdset_index_find_name(host, name, 0);
+    debug(D_RRD_CALLS, "rrdset_find_byname() for chart '%s' in host '%s'", name, rrdhost_hostname(host));
+    RRDSET *st = rrdset_index_find_name(host, name);
     return(st);
 }
 
@@ -128,57 +483,32 @@ char *rrdset_strncpyz_name(char *to, const char *from, size_t length) {
     return to;
 }
 
-int rrdset_set_name(RRDSET *st, const char *name) {
-    if(unlikely(st->name && !strcmp(st->name, name)))
+int rrdset_reset_name(RRDSET *st, const char *name) {
+    if(unlikely(!strcmp(rrdset_name(st), name)))
         return 1;
 
     RRDHOST *host = st->rrdhost;
 
-    debug(D_RRD_CALLS, "rrdset_set_name() old: '%s', new: '%s'", st->name?st->name:"", name);
-
-    char full_name[RRD_ID_LENGTH_MAX + 1];
-    char sanitized_name[CONFIG_MAX_VALUE + 1];
-    char new_name[CONFIG_MAX_VALUE + 1];
-
-    snprintfz(full_name, RRD_ID_LENGTH_MAX, "%s.%s", st->type, name);
-    rrdset_strncpyz_name(sanitized_name, full_name, CONFIG_MAX_VALUE);
-    strncpyz(new_name, sanitized_name, CONFIG_MAX_VALUE);
-
-    if(rrdset_index_find_name(host, new_name, 0)) {
-        debug(D_RRD_CALLS, "RRDSET: chart name '%s' on host '%s' already exists.", new_name, host->hostname);
-        if(!strcmp(st->id, full_name) && !st->name) {
-            unsigned i = 1;
+    debug(D_RRD_CALLS, "rrdset_reset_name() old: '%s', new: '%s'", rrdset_name(st), name);
 
-            do {
-                snprintfz(new_name, CONFIG_MAX_VALUE, "%s_%u", sanitized_name, i);
-                i++;
-            } while (rrdset_index_find_name(host, new_name, 0));
-
-            info("RRDSET: using name '%s' for chart '%s' on host '%s'.", new_name, full_name, host->hostname);
-        } else {
-            return 0;
-        }
-    }
+    STRING *name_string = rrdset_fix_name(host, rrdset_id(st), rrdset_parts_type(st), string2str(st->name), name);
+    if(!name_string) return 0;
 
     if(st->name) {
         rrdset_index_del_name(host, st);
-        st->name = strdupz(new_name);
-        st->hash_name = simple_hash(st->name);
+        string_freez(st->name);
+        st->name = name_string;
         rrdsetvar_rename_all(st);
     }
-    else {
-        st->name = strdupz(new_name);
-        st->hash_name = simple_hash(st->name);
-    }
+    else
+        st->name = name_string;
 
-    rrdset_wrlock(st);
     RRDDIM *rd;
-    rrddim_foreach_write(rd, st)
+    rrddim_foreach_read(rd, st)
         rrddimvar_rename_all(rd);
-    rrdset_unlock(st);
+    rrddim_foreach_done(rd);
 
-    if(unlikely(rrdset_index_add_name(host, st) != st))
-        error("RRDSET: INTERNAL ERROR: attempted to index duplicate chart name '%s'", st->name);
+    rrdset_index_add_name(host, st);
 
     rrdset_flag_clear(st, RRDSET_FLAG_EXPORTING_SEND);
     rrdset_flag_clear(st, RRDSET_FLAG_EXPORTING_IGNORE);
@@ -190,15 +520,65 @@ int rrdset_set_name(RRDSET *st, const char *name) {
     return 2;
 }
 
+// get the timestamp of the last entry in the round-robin database
+time_t rrdset_last_entry_t(RRDSET *st) {
+    RRDDIM *rd;
+    time_t last_entry_t  = 0;
+
+    rrddim_foreach_read(rd, st) {
+        time_t t = rrddim_last_entry_t(rd);
+        if(t > last_entry_t) last_entry_t = t;
+    }
+    rrddim_foreach_done(rd);
+
+    return last_entry_t;
+}
+
+// get the timestamp of first entry in the round-robin database
+time_t rrdset_first_entry_t(RRDSET *st) {
+    RRDDIM *rd;
+    time_t first_entry_t = LONG_MAX;
+
+    rrddim_foreach_read(rd, st) {
+        time_t t = rrddim_first_entry_t(rd);
+        if(t < first_entry_t)
+            first_entry_t = t;
+    }
+    rrddim_foreach_done(rd);
+
+    if (unlikely(LONG_MAX == first_entry_t)) return 0;
+    return first_entry_t;
+}
+
+time_t rrdset_first_entry_t_of_tier(RRDSET *st, size_t tier) {
+    if(unlikely(tier > storage_tiers))
+        return 0;
+
+    RRDDIM *rd;
+    time_t first_entry_t = LONG_MAX;
+
+    rrddim_foreach_read(rd, st) {
+        time_t t = rrddim_first_entry_t_of_tier(rd, tier);
+        if(t && t < first_entry_t)
+            first_entry_t = t;
+    }
+    rrddim_foreach_done(rd);
+
+    if (unlikely(LONG_MAX == first_entry_t)) return 0;
+    return first_entry_t;
+}
+
 inline void rrdset_is_obsolete(RRDSET *st) {
     if(unlikely(rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED))) {
-        info("Cannot obsolete already archived chart %s", st->name);
+        info("Cannot obsolete already archived chart %s", rrdset_name(st));
         return;
     }
 
     if(unlikely(!(rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE)))) {
         rrdset_flag_set(st, RRDSET_FLAG_OBSOLETE);
-        st->rrdhost->obsolete_charts_count++;
+        rrdhost_flag_set(st->rrdhost, RRDHOST_FLAG_PENDING_OBSOLETE_CHARTS);
+
+        st->last_accessed_time = now_realtime_sec();
 
         rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
 
@@ -212,7 +592,7 @@ inline void rrdset_is_obsolete(RRDSET *st) {
 inline void rrdset_isnot_obsolete(RRDSET *st) {
     if(unlikely((rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE)))) {
         rrdset_flag_clear(st, RRDSET_FLAG_OBSOLETE);
-        st->rrdhost->obsolete_charts_count--;
+        st->last_accessed_time = now_realtime_sec();
 
         rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
 
@@ -230,38 +610,52 @@ inline void rrdset_update_heterogeneous_flag(RRDSET *st) {
 
     rrdset_flag_clear(st, RRDSET_FLAG_HOMOGENEOUS_CHECK);
 
-    RRD_ALGORITHM algorithm = st->dimensions->algorithm;
-    collected_number multiplier = ABS(st->dimensions->multiplier);
-    collected_number divisor = ABS(st->dimensions->divisor);
+    bool init = false, is_heterogeneous = false;
+    RRD_ALGORITHM algorithm;
+    collected_number multiplier;
+    collected_number divisor;
 
     rrddim_foreach_read(rd, st) {
+        if(!init) {
+            algorithm = rd->algorithm;
+            multiplier = rd->multiplier;
+            divisor = ABS(rd->divisor);
+            init = true;
+            continue;
+        }
+
         if(algorithm != rd->algorithm || multiplier != ABS(rd->multiplier) || divisor != ABS(rd->divisor)) {
             if(!rrdset_flag_check(st, RRDSET_FLAG_HETEROGENEOUS)) {
                 #ifdef NETDATA_INTERNAL_CHECKS
                 info("Dimension '%s' added on chart '%s' of host '%s' is not homogeneous to other dimensions already present (algorithm is '%s' vs '%s', multiplier is " COLLECTED_NUMBER_FORMAT " vs " COLLECTED_NUMBER_FORMAT ", divisor is " COLLECTED_NUMBER_FORMAT " vs " COLLECTED_NUMBER_FORMAT ").",
-                        rd->name,
-                        st->name,
-                        host->hostname,
-                        rrd_algorithm_name(rd->algorithm), rrd_algorithm_name(algorithm),
-                        rd->multiplier, multiplier,
-                        rd->divisor, divisor
+                     rrddim_name(rd),
+                     rrdset_name(st),
+                     rrdhost_hostname(host),
+                     rrd_algorithm_name(rd->algorithm), rrd_algorithm_name(algorithm),
+                     rd->multiplier, multiplier,
+                     rd->divisor, divisor
                 );
                 #endif
                 rrdset_flag_set(st, RRDSET_FLAG_HETEROGENEOUS);
             }
-            return;
+
+            is_heterogeneous = true;
+            break;
         }
     }
+    rrddim_foreach_done(rd);
 
-    rrdset_flag_clear(st, RRDSET_FLAG_HETEROGENEOUS);
-    rrdcontext_updated_rrdset_flags(st);
+    if(!is_heterogeneous) {
+        rrdset_flag_clear(st, RRDSET_FLAG_HETEROGENEOUS);
+        rrdcontext_updated_rrdset_flags(st);
+    }
 }
 
 // ----------------------------------------------------------------------------
 // RRDSET - reset a chart
 
 void rrdset_reset(RRDSET *st) {
-    debug(D_RRD_CALLS, "rrdset_reset() %s", st->name);
+    debug(D_RRD_CALLS, "rrdset_reset() %s", rrdset_name(st));
 
     st->last_collected_time.tv_sec = 0;
     st->last_collected_time.tv_usec = 0;
@@ -270,7 +664,6 @@ void rrdset_reset(RRDSET *st) {
     st->current_entry = 0;
     st->counter = 0;
     st->counter_done = 0;
-    st->rrddim_page_alignment = 0;
 
     RRDDIM *rd;
     rrddim_foreach_read(rd, st) {
@@ -279,12 +672,13 @@ void rrdset_reset(RRDSET *st) {
         rd->collections_counter = 0;
 
         if(!rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)) {
-            for(int tier = 0; tier < storage_tiers ;tier++) {
+            for(size_t tier = 0; tier < storage_tiers ;tier++) {
                 if(rd->tiers[tier])
-                    rd->tiers[tier]->collect_ops.flush(rd->tiers[tier]->db_collection_handle);
+                    rd->tiers[tier]->collect_ops->flush(rd->tiers[tier]->db_collection_handle);
             }
         }
     }
+    rrddim_foreach_done(rd);
 }
 
 // ----------------------------------------------------------------------------
@@ -336,101 +730,22 @@ static inline void last_updated_time_align(RRDSET *st) {
 
 void rrdset_free(RRDSET *st) {
     if(unlikely(!st)) return;
-
-    RRDHOST *host = st->rrdhost;
-
-    rrdhost_check_wrlock(host);  // make sure we have a write lock on the host
-    rrdset_wrlock(st);                  // lock this RRDSET
-    // info("Removing chart '%s' ('%s')", st->id, st->name);
-
-    // ------------------------------------------------------------------------
-    // remove it from the indexes
-
-    if(unlikely(rrdset_index_del(host, st) != st))
-        error("RRDSET: INTERNAL ERROR: attempt to remove from index chart '%s', removed a different chart.", st->id);
-
-    rrdset_index_del_name(host, st);
-
-    // ------------------------------------------------------------------------
-    // free its children structures
-
-    freez(st->exporting_flags);
-
-    while(st->variables)  rrdsetvar_free(st->variables);
-//  while(st->alarms)     rrdsetcalc_unlink(st->alarms);
-    /* We must free all connected alarms here in case this has been an ephemeral chart whose alarm was
-     * created by a template. This leads to an effective memory leak, which cannot be detected since the
-     * alarms will still be connected to the host, and freed during shutdown. */
-    while(st->alarms)     rrdcalc_unlink_and_free(st->rrdhost, st->alarms);
-    while(st->dimensions) rrddim_free(st, st->dimensions);
-
-    rrdfamily_free(host, st->rrdfamily);
-
-    debug(D_RRD_CALLS, "RRDSET: Cleaning up remaining chart variables for host '%s', chart '%s'", host->hostname, st->id);
-    rrdvar_free_remaining_variables(host, &st->rrdvar_root_index);
-
-    // ------------------------------------------------------------------------
-    // unlink it from the host
-
-    if(st == host->rrdset_root) {
-        host->rrdset_root = st->next;
-    }
-    else {
-        // find the previous one
-        RRDSET *s;
-        for(s = host->rrdset_root; s && s->next != st ; s = s->next) ;
-
-        // bypass it
-        if(s) s->next = st->next;
-        else error("Request to free RRDSET '%s': cannot find it under host '%s'", st->id, host->hostname);
-    }
-
-    rrdset_unlock(st);
-
-    // this has to be after the dimensions are freed
-    rrdcontext_removed_rrdset(st);
-
-    // ------------------------------------------------------------------------
-    // free it
-
-    netdata_rwlock_destroy(&st->rrdset_rwlock);
-
-    // free directly allocated members
-    freez((void *)st->name);
-    freez(st->type);
-    freez(st->family);
-    freez(st->title);
-    freez(st->units);
-    freez(st->context);
-    freez(st->cache_dir);
-    freez(st->plugin_name);
-    freez(st->module_name);
-    freez(st->state->old_title);
-    freez(st->state->old_units);
-    freez(st->state->old_context);
-    rrdlabels_destroy(st->state->chart_labels);
-    freez(st->state);
-    freez(st->chart_uuid);
-
-    rrdset_memory_file_free(st);
-    freez(st);
+    rrdset_index_del(st->rrdhost, st);
 }
 
 void rrdset_save(RRDSET *st) {
-    rrdset_check_rdlock(st);
-
     rrdset_memory_file_save(st);
 
     RRDDIM *rd;
     rrddim_foreach_read(rd, st)
         rrddim_memory_file_save(rd);
+    rrddim_foreach_done(rd);
 }
 
 void rrdset_delete_files(RRDSET *st) {
     RRDDIM *rd;
-    rrdset_check_rdlock(st);
 
-    info("Deleting chart '%s' ('%s') from disk...", st->id, st->name);
+    info("Deleting chart '%s' ('%s') from disk...", rrdset_id(st), rrdset_name(st));
 
     if(st->rrd_memory_mode == RRD_MEMORY_MODE_SAVE || st->rrd_memory_mode == RRD_MEMORY_MODE_MAP) {
         const char *cache_filename = rrdset_cache_filename(st);
@@ -440,7 +755,7 @@ void rrdset_delete_files(RRDSET *st) {
                 error("Cannot delete chart header file '%s'", cache_filename);
         }
         else
-            error("Cannot find the cache filename of chart '%s'", st->id);
+            error("Cannot find the cache filename of chart '%s'", rrdset_id(st));
     }
 
     rrddim_foreach_read(rd, st) {
@@ -451,6 +766,7 @@ void rrdset_delete_files(RRDSET *st) {
         if(unlikely(unlink(cache_filename) == -1))
             error("Cannot delete dimension file '%s'", cache_filename);
     }
+    rrddim_foreach_done(rd);
 
     recursively_delete_dir(st->cache_dir, "left-over chart");
 }
@@ -458,9 +774,7 @@ void rrdset_delete_files(RRDSET *st) {
 void rrdset_delete_obsolete_dimensions(RRDSET *st) {
     RRDDIM *rd;
 
-    rrdset_check_rdlock(st);
-
-    info("Deleting dimensions of chart '%s' ('%s') from disk...", st->id, st->name);
+    info("Deleting dimensions of chart '%s' ('%s') from disk...", rrdset_id(st), rrdset_name(st));
 
     rrddim_foreach_read(rd, st) {
         if(rrddim_flag_check(rd, RRDDIM_FLAG_OBSOLETE)) {
@@ -471,30 +785,12 @@ void rrdset_delete_obsolete_dimensions(RRDSET *st) {
                 error("Cannot delete dimension file '%s'", cache_filename);
         }
     }
+    rrddim_foreach_done(rd);
 }
 
 // ----------------------------------------------------------------------------
 // RRDSET - create a chart
 
-static inline RRDSET *rrdset_find_on_create(RRDHOST *host, const char *fullid) {
-    RRDSET *st = rrdset_find(host, fullid);
-    if(unlikely(st)) {
-        rrdset_isnot_obsolete(st);
-        debug(D_RRD_CALLS, "RRDSET '%s', already exists.", fullid);
-        return st;
-    }
-
-    return NULL;
-}
-
-static inline void rrdset_update_permanent_labels(RRDSET *st) {
-    if(!st->state || !st->state->chart_labels) return;
-
-    rrdlabels_add(st->state->chart_labels, "_collect_plugin", st->plugin_name, RRDLABEL_SRC_AUTO| RRDLABEL_FLAG_PERMANENT);
-    rrdlabels_add(st->state->chart_labels, "_collect_module", st->module_name, RRDLABEL_SRC_AUTO| RRDLABEL_FLAG_PERMANENT);
-    rrdlabels_add(st->state->chart_labels, "_instance_family",   st->family,   RRDLABEL_SRC_AUTO| RRDLABEL_FLAG_PERMANENT);
-}
-
 RRDSET *rrdset_create_custom(
           RRDHOST *host
         , const char *type
@@ -512,7 +808,10 @@ RRDSET *rrdset_create_custom(
         , RRD_MEMORY_MODE memory_mode
         , long history_entries
 ) {
-    if(!type || !type[0]) {
+    if (host != localhost)
+        host->senders_last_chart_command = now_realtime_sec();
+
+    if(!type || !type[0])
         fatal("Cannot create rrd stats without a type: id '%s', name '%s', family '%s', context '%s', title '%s', units '%s', plugin '%s', module '%s'."
               , (id && *id)?id:"<unset>"
               , (name && *name)?name:"<unset>"
@@ -523,10 +822,8 @@ RRDSET *rrdset_create_custom(
               , (plugin && *plugin)?plugin:"<unset>"
               , (module && *module)?module:"<unset>"
         );
-        return NULL;
-    }
 
-    if(!id || !id[0]) {
+    if(!id || !id[0])
         fatal("Cannot create rrd stats without an id: type '%s', name '%s', family '%s', context '%s', title '%s', units '%s', plugin '%s', module '%s'."
               , type
               , (name && *name)?name:"<unset>"
@@ -537,311 +834,55 @@ RRDSET *rrdset_create_custom(
               , (plugin && *plugin)?plugin:"<unset>"
               , (module && *module)?module:"<unset>"
         );
-        return NULL;
-    }
-
-    if (host != localhost) {
-        host->senders_last_chart_command = now_realtime_sec();
-    }
 
     // ------------------------------------------------------------------------
     // check if it already exists
 
-    char fullid[RRD_ID_LENGTH_MAX + 1];
-    snprintfz(fullid, RRD_ID_LENGTH_MAX, "%s.%s", type, id);
-
-    int changed_from_archived_to_active = 0;
-    RRDSET *st = rrdset_find_on_create(host, fullid);
-    if (st) {
-        int mark_rebuild = 0;
-        if (rrdset_flag_check(st, RRDSET_FLAG_ARCHIVED)) {
-            rrdset_flag_clear(st, RRDSET_FLAG_ARCHIVED);
-            changed_from_archived_to_active = 1;
-            mark_rebuild |= META_CHART_ACTIVATED;
-        }
-        char *old_plugin = NULL, *old_module = NULL, *old_title = NULL, *old_context = NULL,
-             *old_title_v = NULL, *old_context_v = NULL, *old_units_v = NULL, *old_units = NULL;
-        int rc;
-
-        if(unlikely(name))
-            rc = rrdset_set_name(st, name);
-        else
-            rc = rrdset_set_name(st, id);
-
-        if (rc == 2)
-            mark_rebuild |= META_CHART_UPDATED;
-
-        if (unlikely(st->priority != priority)) {
-            st->priority = priority;
-            mark_rebuild |= META_CHART_UPDATED;
-        }
-        if (unlikely(st->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE && st->update_every != update_every)) {
-            st->update_every = update_every;
-            mark_rebuild |= META_CHART_UPDATED;
-        }
-
-        if (plugin && st->plugin_name) {
-            if (unlikely(strcmp(plugin, st->plugin_name))) {
-                old_plugin = st->plugin_name;
-                st->plugin_name = strdupz(plugin);
-                mark_rebuild |= META_PLUGIN_UPDATED;
-            }
-        } else {
-            if (plugin != st->plugin_name) { // one is NULL?
-                old_plugin = st->plugin_name;
-                st->plugin_name = plugin ? strdupz(plugin) : NULL;
-                mark_rebuild |= META_PLUGIN_UPDATED;
-            }
-        }
-
-        if (module && st->module_name) {
-            if (unlikely(strcmp(module, st->module_name))) {
-                old_module = st->module_name;
-                st->module_name = strdupz(module);
-                mark_rebuild |= META_MODULE_UPDATED;
-            }
-        } else {
-            if (module != st->module_name) {
-                if (st->module_name && *st->module_name) {
-                    old_module = st->module_name;
-                    st->module_name = module ? strdupz(module) : NULL;
-                    mark_rebuild |= META_MODULE_UPDATED;
-                }
-            }
-        }
-
-        if (unlikely(title && st->state->old_title && strcmp(st->state->old_title, title))) {
-            char *new_title = strdupz(title);
-            old_title_v = st->state->old_title;
-            st->state->old_title = strdupz(title);
-            json_fix_string(new_title);
-            old_title = st->title;
-            st->title = new_title;
-            mark_rebuild |= META_CHART_UPDATED;
-        }
-
-        if (unlikely(units && st->state->old_units && strcmp(st->state->old_units, units))) {
-            char *new_units = strdupz(units);
-            old_units_v = st->state->old_units;
-            st->state->old_units = strdupz(units);
-            json_fix_string(new_units);
-            old_units= st->units;
-            st->units = new_units;
-            mark_rebuild |= META_CHART_UPDATED;
-        }
-
-
-        if (st->chart_type != chart_type) {
-            st->chart_type = chart_type;
-            mark_rebuild |= META_CHART_UPDATED;
-        }
-
-        if (unlikely(context && st->state->old_context && strcmp(st->state->old_context, context))) {
-            char *new_context = strdupz(context);
-            old_context_v = st->state->old_context;
-            st->state->old_context = strdupz(context);
-            json_fix_string(new_context);
-            old_context = st->context;
-            st->context = new_context;
-            st->hash_context = simple_hash(st->context);
-            mark_rebuild |= META_CHART_UPDATED;
-        }
-
-        if (mark_rebuild) {
-            rrdset_flag_clear(st, RRDSET_FLAG_ACLK);
-            freez(old_plugin);
-            freez(old_module);
-            freez(old_title);
-            freez(old_units);
-            freez(old_context);
-            freez(old_title_v);
-            freez(old_units_v);
-            freez(old_context_v);
-            if (mark_rebuild != META_CHART_ACTIVATED) {
-                info("Collector updated metadata for chart %s", st->id);
-                sched_yield();
-            }
-        }
-        if (mark_rebuild & (META_CHART_UPDATED | META_PLUGIN_UPDATED | META_MODULE_UPDATED)) {
-            debug(D_METADATALOG, "CHART [%s] metadata updated", st->id);
-            int rc = update_chart_metadata(st->chart_uuid, st, id, name);
-            if (unlikely(rc))
-                error_report("Failed to update chart metadata in the database");
-
-            if (!changed_from_archived_to_active) {
-                rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
-                rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
-            }
-        }
-        /* Fall-through during switch from archived to active so that the host lock is taken and health is linked */
-        if (!changed_from_archived_to_active) {
-            rrdset_update_permanent_labels(st);
-            rrdcontext_updated_rrdset(st);
-            return st;
-        }
-    }
-
-    rrdhost_wrlock(host);
-
-    st = rrdset_find_on_create(host, fullid);
-    if(st) {
-        if (changed_from_archived_to_active) {
-            rrdset_flag_clear(st, RRDSET_FLAG_ARCHIVED);
-            rrdsetvar_create(st, "last_collected_t",    RRDVAR_TYPE_TIME_T,     &st->last_collected_time.tv_sec, RRDVAR_OPTION_DEFAULT);
-            rrdsetvar_create(st, "collected_total_raw", RRDVAR_TYPE_TOTAL,      &st->last_collected_total,       RRDVAR_OPTION_DEFAULT);
-            rrdsetvar_create(st, "green",               RRDVAR_TYPE_CALCULATED, &st->green,                      RRDVAR_OPTION_DEFAULT);
-            rrdsetvar_create(st, "red",                 RRDVAR_TYPE_CALCULATED, &st->red,                        RRDVAR_OPTION_DEFAULT);
-            rrdsetvar_create(st, "update_every",        RRDVAR_TYPE_INT,        &st->update_every,               RRDVAR_OPTION_DEFAULT);
-            rrdsetcalc_link_matching(st);
-            rrdcalctemplate_link_matching(st);
-        }
-        rrdhost_unlock(host);
-        rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
-        rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
-        rrdcontext_updated_rrdset(st);
-        return st;
-    }
+    char full_id[RRD_ID_LENGTH_MAX + 1];
+    snprintfz(full_id, RRD_ID_LENGTH_MAX, "%s.%s", type, id);
 
     // ------------------------------------------------------------------------
-    // get the options from the config, we need to create it
-
-    long entries = 5;
-    if (memory_mode != RRD_MEMORY_MODE_DBENGINE)
-        entries = align_entries_to_pagesize(memory_mode, history_entries);
-
-    char *cache_dir = rrdset_cache_dir(host, fullid);
-
-    // ------------------------------------------------------------------------
-    // load it or allocate it
+    // allocate it
 
     debug(D_RRD_CALLS, "Creating RRD_STATS for '%s.%s'.", type, id);
 
-    st = callocz(1, sizeof(RRDSET));
-    st->state = callocz(1, sizeof(*st->state));
-
-    strcpy(st->id, fullid);
-    st->hash = simple_hash(st->id);
-
-    st->rrdhost = host;
-    st->cache_dir = cache_dir;
-    st->entries = entries;
-    st->update_every = update_every;
-
-    if(memory_mode == RRD_MEMORY_MODE_SAVE || memory_mode == RRD_MEMORY_MODE_MAP) {
-        if(!rrdset_memory_load_or_create_map_save(st, memory_mode)) {
-            info("Failed to use memory mode %s for chart '%s', falling back to ram", (memory_mode == RRD_MEMORY_MODE_MAP)?"map":"save", st->name);
-            memory_mode = RRD_MEMORY_MODE_RAM;
-        }
-    }
-    st->rrd_memory_mode = memory_mode;
-
-    st->plugin_name = plugin?strdupz(plugin):NULL;
-    st->module_name = module?strdupz(module):NULL;
-    st->chart_type  = chart_type;
-    st->type        = strdupz(type);
-    st->family      = family ? strdupz(family) : strdupz(st->type);
-    json_fix_string(st->family);
-
-    st->state->is_ar_chart = strcmp(st->id, ML_ANOMALY_RATES_CHART_ID) == 0;
-
-    st->units = units ? strdupz(units) : strdupz("");
-    st->state->old_units = strdupz(st->units);
-    json_fix_string(st->units);
-
-    st->context = context ? strdupz(context) : strdupz(st->id);
-    st->state->old_context = strdupz(st->context);
-    json_fix_string(st->context);
-    st->hash_context = simple_hash(st->context);
-
-    st->priority = priority;
-
-    rrdset_flag_set(st, RRDSET_FLAG_SYNC_CLOCK);
-
-    st->green = NAN;
-    st->red = NAN;
-
-    st->gap_when_lost_iterations_above = (int) (gap_when_lost_iterations_above + 2);
-
-    avl_init_lock(&st->dimensions_index, rrddim_compare);
-    avl_init_lock(&st->rrdvar_root_index, rrdvar_compare);
-
-    netdata_rwlock_init(&st->rrdset_rwlock);
-    st->state->chart_labels = rrdlabels_create();
-    rrdset_update_permanent_labels(st);
-
-    if(name && *name && rrdset_set_name(st, name))
-        // we did set the name
-        ;
-    else
-        // could not use the name, use the id
-        rrdset_set_name(st, id);
-
-    st->title = strdupz(title);
-    st->state->old_title = strdupz(st->title);
-    json_fix_string(st->title);
-
-    st->rrdfamily = rrdfamily_create(host, st->family);
-
-    st->next = host->rrdset_root;
-    host->rrdset_root = st;
-
-    if(host->health_enabled) {
-        rrdsetvar_create(st, "last_collected_t",    RRDVAR_TYPE_TIME_T,     &st->last_collected_time.tv_sec, RRDVAR_OPTION_DEFAULT);
-        rrdsetvar_create(st, "collected_total_raw", RRDVAR_TYPE_TOTAL,      &st->last_collected_total,       RRDVAR_OPTION_DEFAULT);
-        rrdsetvar_create(st, "green",               RRDVAR_TYPE_CALCULATED, &st->green,                      RRDVAR_OPTION_DEFAULT);
-        rrdsetvar_create(st, "red",                 RRDVAR_TYPE_CALCULATED, &st->red,                        RRDVAR_OPTION_DEFAULT);
-        rrdsetvar_create(st, "update_every",        RRDVAR_TYPE_INT,        &st->update_every,               RRDVAR_OPTION_DEFAULT);
-    }
-
-    if(unlikely(rrdset_index_add(host, st) != st))
-        error("RRDSET: INTERNAL ERROR: attempt to index duplicate chart '%s'", st->id);
-
-    rrdsetcalc_link_matching(st);
-    rrdcalctemplate_link_matching(st);
-
-    st->chart_uuid = find_chart_uuid(host, type, id, name);
-    if (unlikely(!st->chart_uuid))
-        st->chart_uuid = create_chart_uuid(st, id, name);
-    else
-        update_chart_metadata(st->chart_uuid, st, id, name);
-
-    store_active_chart(st->chart_uuid);
-    compute_chart_hash(st);
-
-    rrdhost_unlock(host);
-    rrdcontext_updated_rrdset(st);
+    struct rrdset_constructor tmp = {
+        .host = host,
+        .type = type,
+        .id = id,
+        .name = name,
+        .family = family,
+        .context = context,
+        .title = title,
+        .units = units,
+        .plugin = plugin,
+        .module = module,
+        .priority = priority,
+        .update_every = update_every,
+        .chart_type = chart_type,
+        .memory_mode = memory_mode,
+        .history_entries = history_entries,
+    };
+
+    RRDSET *st = rrdset_index_add(host, full_id, &tmp);
     return(st);
 }
 
-
 // ----------------------------------------------------------------------------
 // RRDSET - data collection iteration control
 
-inline void rrdset_next_usec_unfiltered(RRDSET *st, usec_t microseconds) {
-    if(unlikely(!st->last_collected_time.tv_sec || !microseconds || (rrdset_flag_check(st, RRDSET_FLAG_SYNC_CLOCK)))) {
-        // call the full next_usec() function
-        rrdset_next_usec(st, microseconds);
-        return;
-    }
-
-    st->usec_since_last_update = microseconds;
-}
-
-inline void rrdset_next_usec(RRDSET *st, usec_t microseconds) {
-    struct timeval now;
-    now_realtime_timeval(&now);
-
+void rrdset_timed_next(RRDSET *st, struct timeval now, usec_t duration_since_last_update) {
     #ifdef NETDATA_INTERNAL_CHECKS
     char *discard_reason = NULL;
-    usec_t discarded = microseconds;
+    usec_t discarded = duration_since_last_update;
     #endif
 
     if(unlikely(rrdset_flag_check(st, RRDSET_FLAG_SYNC_CLOCK))) {
         // the chart needs to be re-synced to current time
         rrdset_flag_clear(st, RRDSET_FLAG_SYNC_CLOCK);
 
-        // discard the microseconds supplied
-        microseconds = 0;
+        // discard the duration supplied
+        duration_since_last_update = 0;
 
         #ifdef NETDATA_INTERNAL_CHECKS
         if(!discard_reason) discard_reason = "SYNC CLOCK FLAG";
@@ -850,14 +891,14 @@ inline void rrdset_next_usec(RRDSET *st, usec_t microseconds) {
 
     if(unlikely(!st->last_collected_time.tv_sec)) {
         // the first entry
-        microseconds = st->update_every * USEC_PER_SEC;
+        duration_since_last_update = st->update_every * USEC_PER_SEC;
         #ifdef NETDATA_INTERNAL_CHECKS
         if(!discard_reason) discard_reason = "FIRST DATA COLLECTION";
         #endif
     }
-    else if(unlikely(!microseconds)) {
+    else if(unlikely(!duration_since_last_update)) {
         // no dt given by the plugin
-        microseconds = dt_usec(&now, &st->last_collected_time);
+        duration_since_last_update = dt_usec(&now, &st->last_collected_time);
         #ifdef NETDATA_INTERNAL_CHECKS
         if(!discard_reason) discard_reason = "NO USEC GIVEN BY COLLECTOR";
         #endif
@@ -870,7 +911,13 @@ inline void rrdset_next_usec(RRDSET *st, usec_t microseconds) {
             // oops! the database is in the future
             #ifdef NETDATA_INTERNAL_CHECKS
             info("RRD database for chart '%s' on host '%s' is %0.5" NETDATA_DOUBLE_MODIFIER
-                " secs in the future (counter #%zu, update #%zu). Adjusting it to current time.", st->id, st->rrdhost->hostname, (NETDATA_DOUBLE)-since_last_usec / USEC_PER_SEC, st->counter, st->counter_done);
+                " secs in the future (counter #%zu, update #%zu). Adjusting it to current time."
+                , rrdset_id(st)
+                , rrdhost_hostname(st->rrdhost)
+                , (NETDATA_DOUBLE)-since_last_usec / USEC_PER_SEC
+                , st->counter
+                , st->counter_done
+                );
             #endif
 
             st->last_collected_time.tv_sec  = now.tv_sec - st->update_every;
@@ -881,7 +928,7 @@ inline void rrdset_next_usec(RRDSET *st, usec_t microseconds) {
             st->last_updated.tv_usec = now.tv_usec;
             last_updated_time_align(st);
 
-            microseconds    = st->update_every * USEC_PER_SEC;
+            duration_since_last_update = st->update_every * USEC_PER_SEC;
             #ifdef NETDATA_INTERNAL_CHECKS
             if(!discard_reason) discard_reason = "COLLECTION TIME IN FUTURE";
             #endif
@@ -890,24 +937,24 @@ inline void rrdset_next_usec(RRDSET *st, usec_t microseconds) {
             // oops! the database is too far behind
             #ifdef NETDATA_INTERNAL_CHECKS
             info("RRD database for chart '%s' on host '%s' is %0.5" NETDATA_DOUBLE_MODIFIER
-                " secs in the past (counter #%zu, update #%zu). Adjusting it to current time.", st->id, st->rrdhost->hostname, (NETDATA_DOUBLE)since_last_usec / USEC_PER_SEC, st->counter, st->counter_done);
+                " secs in the past (counter #%zu, update #%zu). Adjusting it to current time.", rrdset_id(st), rrdhost_hostname(st->rrdhost), (NETDATA_DOUBLE)since_last_usec / USEC_PER_SEC, st->counter, st->counter_done);
             #endif
 
-            microseconds = (usec_t)since_last_usec;
+            duration_since_last_update = (usec_t)since_last_usec;
             #ifdef NETDATA_INTERNAL_CHECKS
             if(!discard_reason) discard_reason = "COLLECTION TIME TOO FAR IN THE PAST";
             #endif
         }
 
 #ifdef NETDATA_INTERNAL_CHECKS
-        if(since_last_usec > 0 && (susec_t)microseconds < since_last_usec) {
+        if(since_last_usec > 0 && (susec_t) duration_since_last_update < since_last_usec) {
             static __thread susec_t min_delta = USEC_PER_SEC * 3600, permanent_min_delta = 0;
             static __thread time_t last_t = 0;
 
             // the first time initialize it so that it will make the check later
             if(last_t == 0) last_t = now.tv_sec + 60;
 
-            susec_t delta = since_last_usec - (susec_t)microseconds;
+            susec_t delta = since_last_usec - (susec_t) duration_since_last_update;
             if(delta < min_delta) min_delta = delta;
 
             if(now.tv_sec >= last_t + 60) {
@@ -924,31 +971,49 @@ inline void rrdset_next_usec(RRDSET *st, usec_t microseconds) {
 #endif
     }
 
-    #ifdef NETDATA_INTERNAL_CHECKS
-    debug(D_RRD_CALLS, "rrdset_next_usec() for chart %s with microseconds %llu", st->name, microseconds);
-    rrdset_debug(st, "NEXT: %llu microseconds", microseconds);
+    debug(D_RRD_CALLS, "rrdset_timed_next() for chart %s with duration since last update %llu usec", rrdset_name(st), duration_since_last_update);
+    rrdset_debug(st, "NEXT: %llu microseconds", duration_since_last_update);
 
-    if(discarded && discarded != microseconds)
-        info("host '%s', chart '%s': discarded data collection time of %llu usec, replaced with %llu usec, reason: '%s'", st->rrdhost->hostname, st->id, discarded, microseconds, discard_reason?discard_reason:"UNDEFINED");
+    internal_error(discarded && discarded != duration_since_last_update,
+                   "host '%s', chart '%s': discarded data collection time of %llu usec, "
+                   "replaced with %llu usec, reason: '%s'"
+                   , rrdhost_hostname(st->rrdhost)
+                   , rrdset_id(st)
+                   , discarded
+                   , duration_since_last_update
+                   , discard_reason?discard_reason:"UNDEFINED"
+                   );
 
-    #endif
+    st->usec_since_last_update = duration_since_last_update;
+}
+
+inline void rrdset_next_usec_unfiltered(RRDSET *st, usec_t duration_since_last_update) {
+    if(unlikely(!st->last_collected_time.tv_sec || !duration_since_last_update || (rrdset_flag_check(st, RRDSET_FLAG_SYNC_CLOCK)))) {
+        // call the full next_usec() function
+        rrdset_next_usec(st, duration_since_last_update);
+        return;
+    }
 
-    st->usec_since_last_update = microseconds;
+    st->usec_since_last_update = duration_since_last_update;
 }
 
+inline void rrdset_next_usec(RRDSET *st, usec_t duration_since_last_update) {
+    struct timeval now;
+
+    now_realtime_timeval(&now);
+    rrdset_timed_next(st, now, duration_since_last_update);
+}
 
 // ----------------------------------------------------------------------------
 // RRDSET - process the collected values for all dimensions of a chart
 
-static inline usec_t rrdset_init_last_collected_time(RRDSET *st) {
-    now_realtime_timeval(&st->last_collected_time);
+static inline usec_t rrdset_init_last_collected_time(RRDSET *st, struct timeval now) {
+    st->last_collected_time = now;
     last_collected_time_align(st);
 
     usec_t last_collect_ut = st->last_collected_time.tv_sec * USEC_PER_SEC + st->last_collected_time.tv_usec;
 
-    #ifdef NETDATA_INTERNAL_CHECKS
     rrdset_debug(st, "initialized last collected time to %0.3" NETDATA_DOUBLE_MODIFIER, (NETDATA_DOUBLE)last_collect_ut / USEC_PER_SEC);
-    #endif
 
     return last_collect_ut;
 }
@@ -959,9 +1024,7 @@ static inline usec_t rrdset_update_last_collected_time(RRDSET *st) {
     st->last_collected_time.tv_sec = (time_t) (ut / USEC_PER_SEC);
     st->last_collected_time.tv_usec = (suseconds_t) (ut % USEC_PER_SEC);
 
-    #ifdef NETDATA_INTERNAL_CHECKS
     rrdset_debug(st, "updated last collected time to %0.3" NETDATA_DOUBLE_MODIFIER, (NETDATA_DOUBLE)last_collect_ut / USEC_PER_SEC);
-    #endif
 
     return last_collect_ut;
 }
@@ -978,22 +1041,51 @@ static inline usec_t rrdset_init_last_updated_time(RRDSET *st) {
 
     usec_t last_updated_ut = st->last_updated.tv_sec * USEC_PER_SEC + st->last_updated.tv_usec;
 
-    #ifdef NETDATA_INTERNAL_CHECKS
     rrdset_debug(st, "initialized last updated time to %0.3" NETDATA_DOUBLE_MODIFIER, (NETDATA_DOUBLE)last_updated_ut / USEC_PER_SEC);
-    #endif
 
     return last_updated_ut;
 }
 
+static __thread size_t rrdset_done_statistics_points_stored_per_tier[RRD_STORAGE_TIERS];
+
 static inline time_t tier_next_point_time(RRDDIM *rd, struct rrddim_tier *t, time_t now) {
     time_t loop = (time_t)rd->update_every * (time_t)t->tier_grouping;
     return now + loop - ((now + loop) % loop);
 }
 
-void store_metric_at_tier(RRDDIM *rd, struct rrddim_tier *t, STORAGE_POINT sp, usec_t now_ut) {
+void store_metric_at_tier(RRDDIM *rd, size_t tier, struct rrddim_tier *t, STORAGE_POINT sp, usec_t now_ut __maybe_unused) {
     if (unlikely(!t->next_point_time))
         t->next_point_time = tier_next_point_time(rd, t, sp.end_time);
 
+    if(unlikely(sp.start_time > t->next_point_time)) {
+        if (likely(!storage_point_is_unset(t->virtual_point))) {
+
+            t->collect_ops->store_metric(
+                t->db_collection_handle,
+                t->next_point_time * USEC_PER_SEC,
+                t->virtual_point.sum,
+                t->virtual_point.min,
+                t->virtual_point.max,
+                t->virtual_point.count,
+                t->virtual_point.anomaly_count,
+                t->virtual_point.flags);
+        }
+        else {
+            t->collect_ops->store_metric(
+                t->db_collection_handle,
+                t->next_point_time * USEC_PER_SEC,
+                NAN,
+                NAN,
+                NAN,
+                0,
+                0, SN_FLAG_NONE);
+        }
+
+        rrdset_done_statistics_points_stored_per_tier[tier]++;
+        t->virtual_point.count = 0; // make the point unset
+        t->next_point_time = tier_next_point_time(rd, t, sp.end_time);
+    }
+
     // merge the dates into our virtual point
     if (unlikely(sp.start_time < t->virtual_point.start_time))
         t->virtual_point.start_time = sp.start_time;
@@ -1019,72 +1111,105 @@ void store_metric_at_tier(RRDDIM *rd, struct rrddim_tier *t, STORAGE_POINT sp, u
             t->virtual_point = sp;
         }
     }
-
-    if(unlikely(sp.end_time >= t->next_point_time)) {
-        if (likely(!storage_point_is_unset(t->virtual_point))) {
-
-            t->collect_ops.store_metric(
-                t->db_collection_handle,
-                now_ut,
-                t->virtual_point.sum,
-                t->virtual_point.min,
-                t->virtual_point.max,
-                t->virtual_point.count,
-                t->virtual_point.anomaly_count,
-                t->virtual_point.flags);
-        }
-        else {
-            t->collect_ops.store_metric(
-                t->db_collection_handle,
-                now_ut,
-                NAN,
-                NAN,
-                NAN,
-                0,
-                0, SN_FLAG_NONE);
+}
+#ifdef NETDATA_LOG_COLLECTION_ERRORS
+void rrddim_store_metric_with_trace(RRDDIM *rd, usec_t point_end_time_ut, NETDATA_DOUBLE n, SN_FLAGS flags, const char *function) {
+#else // !NETDATA_LOG_COLLECTION_ERRORS
+void rrddim_store_metric(RRDDIM *rd, usec_t point_end_time_ut, NETDATA_DOUBLE n, SN_FLAGS flags) {
+#endif // !NETDATA_LOG_COLLECTION_ERRORS
+#ifdef NETDATA_LOG_COLLECTION_ERRORS
+    rd->rrddim_store_metric_count++;
+
+    if(likely(rd->rrddim_store_metric_count > 1)) {
+        usec_t expected = rd->rrddim_store_metric_last_ut + rd->update_every * USEC_PER_SEC;
+
+        if(point_end_time_ut != rd->rrddim_store_metric_last_ut) {
+            internal_error(true,
+                           "%s COLLECTION: 'host:%s/chart:%s/dim:%s' granularity %d, collection %zu, expected to store at tier 0 a value at %llu, but it gave %llu [%s%llu usec] (called from %s(), previously by %s())",
+                           (point_end_time_ut < rd->rrddim_store_metric_last_ut) ? "**PAST**" : "GAP",
+                           rrdhost_hostname(rd->rrdset->rrdhost), rrdset_id(rd->rrdset), rrddim_id(rd),
+                           rd->update_every,
+                           rd->rrddim_store_metric_count,
+                           expected, point_end_time_ut,
+                           (point_end_time_ut < rd->rrddim_store_metric_last_ut)?"by -" : "gap ",
+                           expected - point_end_time_ut,
+                           function,
+                           rd->rrddim_store_metric_last_caller?rd->rrddim_store_metric_last_caller:"none");
         }
-
-        t->virtual_point.count = 0;
-        t->next_point_time = tier_next_point_time(rd, t, sp.end_time);
     }
-}
 
-static void store_metric(RRDDIM *rd, usec_t point_end_time_ut, NETDATA_DOUBLE n, SN_FLAGS flags) {
+    rd->rrddim_store_metric_last_ut = point_end_time_ut;
+    rd->rrddim_store_metric_last_caller = function;
+#endif // NETDATA_LOG_COLLECTION_ERRORS
 
     // store the metric on tier 0
-    rd->tiers[0]->collect_ops.store_metric(rd->tiers[0]->db_collection_handle, point_end_time_ut, n, 0, 0, 1, 0, flags);
-
-    for(int tier = 1; tier < storage_tiers ;tier++) {
+    rd->tiers[0]->collect_ops->store_metric(rd->tiers[0]->db_collection_handle, point_end_time_ut, n, 0, 0, 1, 0, flags);
+    rrdset_done_statistics_points_stored_per_tier[0]++;
+
+    time_t now = (time_t)(point_end_time_ut / USEC_PER_SEC);
+
+    STORAGE_POINT sp = {
+        .start_time = now - rd->update_every,
+        .end_time = now,
+        .min = n,
+        .max = n,
+        .sum = n,
+        .count = 1,
+        .anomaly_count = (flags & SN_FLAG_NOT_ANOMALOUS) ? 0 : 1,
+        .flags = flags
+    };
+
+    for(size_t tier = 1; tier < storage_tiers ;tier++) {
         if(unlikely(!rd->tiers[tier])) continue;
 
         struct rrddim_tier *t = rd->tiers[tier];
 
-        time_t now = (time_t)(point_end_time_ut / USEC_PER_SEC);
-
-        if(!t->last_collected_ut) {
+        if(!rrddim_option_check(rd, RRDDIM_OPTION_BACKFILLED_HIGH_TIERS)) {
             // we have not collected this tier before
             // let's fill any gap that may exist
             rrdr_fill_tier_gap_from_smaller_tiers(rd, tier, now);
+            rrddim_option_set(rd, RRDDIM_OPTION_BACKFILLED_HIGH_TIERS);
         }
 
-        STORAGE_POINT sp = {
-            .start_time = now - rd->update_every,
-            .end_time = now,
-            .min = n,
-            .max = n,
-            .sum = n,
-            .count = 1,
-            .anomaly_count = (flags & SN_FLAG_NOT_ANOMALOUS) ? 0 : 1,
-            .flags = flags
-        };
+        store_metric_at_tier(rd, tier, t, sp, point_end_time_ut);
+    }
+}
+
+void store_metric_collection_completed() {
+    global_statistics_rrdset_done_chart_collection_completed(rrdset_done_statistics_points_stored_per_tier);
+}
+
+// caching of dimensions rrdset_done() and rrdset_done_interpolate() loop through
+struct rda_item {
+    const DICTIONARY_ITEM *item;
+    RRDDIM *rd;
+};
+
+static __thread struct rda_item *thread_rda = NULL;
+static __thread size_t thread_rda_entries = 0;
 
-        t->last_collected_ut = point_end_time_ut;
-        store_metric_at_tier(rd, t, sp, point_end_time_ut);
+struct rda_item *rrdset_thread_rda(size_t *dimensions) {
+
+    if(unlikely(!thread_rda || (*dimensions) > thread_rda_entries)) {
+        freez(thread_rda);
+        thread_rda = mallocz((*dimensions) * sizeof(struct rda_item));
+        thread_rda_entries = *dimensions;
     }
+
+    *dimensions = thread_rda_entries;
+    return thread_rda;
+}
+
+void rrdset_thread_rda_free(void) {
+    freez(thread_rda);
+    thread_rda = NULL;
+    thread_rda_entries = 0;
 }
 
 static inline size_t rrdset_done_interpolate(
         RRDSET *st
+        , struct rda_item *rda_base
+        , size_t rda_slots
         , usec_t update_every_ut
         , usec_t last_stored_ut
         , usec_t next_store_ut
@@ -1113,17 +1238,26 @@ static inline size_t rrdset_done_interpolate(
 
     for( ; next_store_ut <= now_collect_ut ; last_collect_ut = next_store_ut, next_store_ut += update_every_ut, iterations-- ) {
 
-        #ifdef NETDATA_INTERNAL_CHECKS
-        if(iterations < 0) { error("INTERNAL CHECK: %s: iterations calculation wrapped! first_ut = %llu, last_stored_ut = %llu, next_store_ut = %llu, now_collect_ut = %llu", st->name, first_ut, last_stored_ut, next_store_ut, now_collect_ut); }
+        internal_error(iterations < 0,
+                       "RRDSET: '%s': iterations calculation wrapped! "
+                       "first_ut = %llu, last_stored_ut = %llu, next_store_ut = %llu, now_collect_ut = %llu"
+                       , rrdset_id(st)
+                       , first_ut
+                       , last_stored_ut
+                       , next_store_ut
+                       , now_collect_ut
+                       );
+
         rrdset_debug(st, "last_stored_ut = %0.3" NETDATA_DOUBLE_MODIFIER " (last updated time)", (NETDATA_DOUBLE)last_stored_ut/USEC_PER_SEC);
         rrdset_debug(st, "next_store_ut  = %0.3" NETDATA_DOUBLE_MODIFIER " (next interpolation point)", (NETDATA_DOUBLE)next_store_ut/USEC_PER_SEC);
-        #endif
 
         last_ut = next_store_ut;
 
-        rrddim_foreach_read(rd, st) {
-            if (rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED))
-                continue;
+        struct rda_item *rda;
+        size_t dim_id;
+        for(dim_id = 0, rda = rda_base ; dim_id < rda_slots ; ++dim_id, ++rda) {
+            rd = rda->rd;
+            if(unlikely(!rd)) continue;
 
             NETDATA_DOUBLE new_value;
 
@@ -1135,18 +1269,16 @@ static inline size_t rrdset_done_interpolate(
                                    / (NETDATA_DOUBLE)(now_collect_ut - last_collect_ut)
                             );
 
-                    #ifdef NETDATA_INTERNAL_CHECKS
                     rrdset_debug(st, "%s: CALC2 INC " NETDATA_DOUBLE_FORMAT " = "
                                  NETDATA_DOUBLE_FORMAT
                                 " * (%llu - %llu)"
                                 " / (%llu - %llu)"
-                              , rd->name
+                              , rrddim_name(rd)
                               , new_value
                               , rd->calculated_value
                               , next_store_ut, last_collect_ut
                               , now_collect_ut, last_collect_ut
                     );
-                    #endif
 
                     rd->calculated_value -= new_value;
                     new_value += rd->last_calculated_value;
@@ -1155,12 +1287,10 @@ static inline size_t rrdset_done_interpolate(
 
                     if(unlikely(next_store_ut - last_stored_ut < update_every_ut)) {
 
-                        #ifdef NETDATA_INTERNAL_CHECKS
                         rrdset_debug(st, "%s: COLLECTION POINT IS SHORT " NETDATA_DOUBLE_FORMAT " - EXTRAPOLATING",
-                                    rd->name
+                                    rrddim_name(rd)
                                   , (NETDATA_DOUBLE)(next_store_ut - last_stored_ut)
                         );
-                        #endif
 
                         new_value = new_value * (NETDATA_DOUBLE)(st->update_every * USEC_PER_SEC) / (NETDATA_DOUBLE)(next_store_ut - last_stored_ut);
                     }
@@ -1189,24 +1319,23 @@ static inline size_t rrdset_done_interpolate(
                                     +  rd->last_calculated_value
                                 );
 
-                        #ifdef NETDATA_INTERNAL_CHECKS
                         rrdset_debug(st, "%s: CALC2 DEF " NETDATA_DOUBLE_FORMAT " = ((("
                                             "(" NETDATA_DOUBLE_FORMAT " - " NETDATA_DOUBLE_FORMAT ")"
                                             " * %llu"
-                                            " / %llu) + " NETDATA_DOUBLE_FORMAT, rd->name
+                                            " / %llu) + " NETDATA_DOUBLE_FORMAT, rrddim_name(rd)
                                   , new_value
                                   , rd->calculated_value, rd->last_calculated_value
                                   , (next_store_ut - first_ut)
                                   , (now_collect_ut - first_ut), rd->last_calculated_value
                         );
-                        #endif
                     }
                     break;
             }
 
             if(unlikely(!store_this_entry)) {
                 (void) ml_is_anomalous(rd, 0, false);
-                store_metric(rd, next_store_ut, NAN, SN_FLAG_NONE);
+                rrddim_store_metric(rd, next_store_ut, NAN, SN_FLAG_NONE);
+                rrdcontext_collected_rrddim(rd);
                 continue;
             }
 
@@ -1218,17 +1347,17 @@ static inline size_t rrdset_done_interpolate(
                     dim_storage_flags &= ~((storage_number)SN_FLAG_NOT_ANOMALOUS);
                 }
 
-                store_metric(rd, next_store_ut, new_value, dim_storage_flags);
+                rrddim_store_metric(rd, next_store_ut, new_value, dim_storage_flags);
+                rrdcontext_collected_rrddim(rd);
                 rd->last_stored_value = new_value;
             }
             else {
                 (void) ml_is_anomalous(rd, 0, false);
 
-                #ifdef NETDATA_INTERNAL_CHECKS
-                rrdset_debug(st, "%s: STORE[%ld] = NON EXISTING ", rd->name, current_entry);
-                #endif
+                rrdset_debug(st, "%s: STORE[%ld] = NON EXISTING ", rrddim_name(rd), current_entry);
 
-                store_metric(rd, next_store_ut, NAN, SN_FLAG_NONE);
+                rrddim_store_metric(rd, next_store_ut, NAN, SN_FLAG_NONE);
+                rrdcontext_collected_rrddim(rd);
                 rd->last_stored_value = NAN;
             }
 
@@ -1274,11 +1403,10 @@ static inline void rrdset_done_fill_the_gap(RRDSET *st) {
             rd->db[current_entry] = pack_storage_number(NAN, SN_FLAG_NONE);
             current_entry = ((current_entry + 1) >= entries) ? 0 : current_entry + 1;
 
-            #ifdef NETDATA_INTERNAL_CHECKS
-            rrdset_debug(st, "%s: STORE[%ld] = NON EXISTING (FILLED THE GAP)", rd->name, current_entry);
-            #endif
+            rrdset_debug(st, "%s: STORE[%ld] = NON EXISTING (FILLED THE GAP)", rrddim_name(rd), current_entry);
         }
     }
+    rrddim_foreach_done(rd);
 
     if(c > 0) {
         c--;
@@ -1292,10 +1420,19 @@ static inline void rrdset_done_fill_the_gap(RRDSET *st) {
 }
 
 void rrdset_done(RRDSET *st) {
+    struct timeval now;
+
+    now_realtime_timeval(&now);
+    rrdset_timed_done(st, now, /* pending_rrdset_next = */ st->counter_done != 0);
+}
+
+void rrdset_timed_done(RRDSET *st, struct timeval now, bool pending_rrdset_next) {
     if(unlikely(netdata_exit)) return;
 
-    debug(D_RRD_CALLS, "rrdset_done() for chart %s", st->name);
-    rrdcontext_collected_rrdset(st);
+    if (pending_rrdset_next)
+        rrdset_next(st);
+
+    debug(D_RRD_CALLS, "rrdset_done() for chart '%s'", rrdset_name(st));
 
     RRDDIM *rd;
 
@@ -1312,44 +1449,29 @@ void rrdset_done(RRDSET *st) {
 
     netdata_thread_disable_cancelability();
 
-    // a read lock is OK here
-    rrdset_rdlock(st);
-
-#ifdef ENABLE_ACLK
-    if (likely(!st->state->is_ar_chart)) {
-        if (unlikely(!rrdset_flag_check(st, RRDSET_FLAG_ACLK))) {
-            if (likely(st->dimensions && st->counter_done && !queue_chart_to_aclk(st))) {
-                rrdset_flag_set(st, RRDSET_FLAG_ACLK);
-            }
-        }
-    }
-#endif
-
     if(unlikely(rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE))) {
-        error("Chart '%s' has the OBSOLETE flag set, but it is collected.", st->id);
+        error("Chart '%s' has the OBSOLETE flag set, but it is collected.", rrdset_id(st));
         rrdset_isnot_obsolete(st);
     }
 
     // check if the chart has a long time to be updated
     if(unlikely(st->usec_since_last_update > st->entries * update_every_ut &&
                 st->rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE && st->rrd_memory_mode != RRD_MEMORY_MODE_NONE)) {
-        info("host '%s', chart %s: took too long to be updated (counter #%zu, update #%zu, %0.3" NETDATA_DOUBLE_MODIFIER
-            " secs). Resetting it.", st->rrdhost->hostname, st->name, st->counter, st->counter_done, (NETDATA_DOUBLE)st->usec_since_last_update / USEC_PER_SEC);
+        info("host '%s', chart '%s': took too long to be updated (counter #%zu, update #%zu, %0.3" NETDATA_DOUBLE_MODIFIER
+            " secs). Resetting it.", rrdhost_hostname(st->rrdhost), rrdset_id(st), st->counter, st->counter_done, (NETDATA_DOUBLE)st->usec_since_last_update / USEC_PER_SEC);
         rrdset_reset(st);
         st->usec_since_last_update = update_every_ut;
         store_this_entry = 0;
         first_entry = 1;
     }
 
-    #ifdef NETDATA_INTERNAL_CHECKS
     rrdset_debug(st, "microseconds since last update: %llu", st->usec_since_last_update);
-    #endif
 
     // set last_collected_time
     if(unlikely(!st->last_collected_time.tv_sec)) {
         // it is the first entry
         // set the last_collected_time to now
-        last_collect_ut = rrdset_init_last_collected_time(st) - update_every_ut;
+        last_collect_ut = rrdset_init_last_collected_time(st, now) - update_every_ut;
 
         // the first entry should not be stored
         store_this_entry = 0;
@@ -1380,9 +1502,9 @@ void rrdset_done(RRDSET *st) {
     if(unlikely(dt_usec(&st->last_collected_time, &st->last_updated) > st->entries * update_every_ut &&
                 st->rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)) {
         info(
-            "%s: too old data (last updated at %"PRId64".%"PRId64", last collected at %"PRId64".%"PRId64"). "
+            "'%s': too old data (last updated at %"PRId64".%"PRId64", last collected at %"PRId64".%"PRId64"). "
             "Resetting it. Will not store the next entry.",
-            st->name,
+            rrdset_id(st),
             (int64_t)st->last_updated.tv_sec,
             (int64_t)st->last_updated.tv_usec,
             (int64_t)st->last_collected_time.tv_sec,
@@ -1402,9 +1524,9 @@ void rrdset_done(RRDSET *st) {
     if(unlikely(st->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE &&
                 dt_usec(&st->last_collected_time, &st->last_updated) > (RRDENG_BLOCK_SIZE / sizeof(storage_number)) * update_every_ut)) {
         info(
-            "%s: too old data (last updated at %" PRId64 ".%" PRId64 ", last collected at %" PRId64 ".%" PRId64 "). "
+            "'%s': too old data (last updated at %" PRId64 ".%" PRId64 ", last collected at %" PRId64 ".%" PRId64 "). "
             "Resetting it. Will not store the next entry.",
-            st->name,
+            rrdset_id(st),
             (int64_t)st->last_updated.tv_sec,
             (int64_t)st->last_updated.tv_usec,
             (int64_t)st->last_collected_time.tv_sec,
@@ -1449,79 +1571,108 @@ void rrdset_done(RRDSET *st) {
             store_this_entry = 1;
             last_collect_ut = next_store_ut - update_every_ut;
 
-            #ifdef NETDATA_INTERNAL_CHECKS
             rrdset_debug(st, "Fixed first entry.");
-            #endif
         }
         else {
             store_this_entry = 0;
 
-            #ifdef NETDATA_INTERNAL_CHECKS
             rrdset_debug(st, "Will not store the next entry.");
-            #endif
         }
     }
 
 after_first_database_work:
     st->counter_done++;
 
-    if(unlikely(st->rrdhost->rrdpush_send_enabled))
+    if(unlikely(rrdhost_has_rrdpush_sender_enabled(st->rrdhost)))
         rrdset_done_push(st);
-    if (unlikely(st->rrd_memory_mode == RRD_MEMORY_MODE_NONE)) {
-        goto after_second_database_work;
-    }
 
-    #ifdef NETDATA_INTERNAL_CHECKS
-    rrdset_debug(st, "last_collect_ut = %0.3" NETDATA_DOUBLE_MODIFIER " (last collection time)", (NETDATA_DOUBLE)last_collect_ut/USEC_PER_SEC);
-    rrdset_debug(st, "now_collect_ut  = %0.3" NETDATA_DOUBLE_MODIFIER " (current collection time)", (NETDATA_DOUBLE)now_collect_ut/USEC_PER_SEC);
-    rrdset_debug(st, "last_stored_ut  = %0.3" NETDATA_DOUBLE_MODIFIER " (last updated time)", (NETDATA_DOUBLE)last_stored_ut/USEC_PER_SEC);
-    rrdset_debug(st, "next_store_ut   = %0.3" NETDATA_DOUBLE_MODIFIER " (next interpolation point)", (NETDATA_DOUBLE)next_store_ut/USEC_PER_SEC);
-    #endif
+    uint32_t has_reset_value = 0;
 
-    // calculate totals and count the dimensions
-    int dimensions = 0;
-    st->collected_total = 0;
+    size_t rda_slots = dictionary_entries(st->rrddim_root_index);
+    struct rda_item *rda_base = rrdset_thread_rda(&rda_slots);
+
+    size_t dim_id;
+    size_t dimensions = 0;
+    struct rda_item *rda = rda_base;
+    total_number collected_total = 0;
+    total_number last_collected_total = 0;
     rrddim_foreach_read(rd, st) {
-        if (rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED))
+        if(rd_dfe.counter >= rda_slots)
+            break;
+
+        rda = &rda_base[dimensions++];
+
+        if(rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED)) {
+            rda->item = NULL;
+            rda->rd = NULL;
             continue;
+        }
+
+        // store the dimension in the array
+        rda->item = dictionary_acquired_item_dup(st->rrddim_root_index, rd_dfe.item);
+        rda->rd = dictionary_acquired_item_value(rda->item);
+
+        // calculate totals
+        if(likely(rd->updated)) {
+            // if the new is smaller than the old (an overflow, or reset), set the old equal to the new
+            // to reset the calculation (it will give zero as the calculation for this second)
+            if(unlikely(rd->algorithm == RRD_ALGORITHM_PCENT_OVER_DIFF_TOTAL && rd->last_collected_value > rd->collected_value)) {
+                debug(D_RRD_STATS, "'%s' / '%s': RESET or OVERFLOW. Last collected value = " COLLECTED_NUMBER_FORMAT ", current = " COLLECTED_NUMBER_FORMAT
+                , rrdset_id(st)
+                , rrddim_name(rd)
+                , rd->last_collected_value
+                , rd->collected_value
+                );
 
-        dimensions++;
+                if(!(rrddim_option_check(rd, RRDDIM_OPTION_DONT_DETECT_RESETS_OR_OVERFLOWS)))
+                    has_reset_value = 1;
 
-        if(likely(rd->updated))
-            st->collected_total += rd->collected_value;
+                rd->last_collected_value = rd->collected_value;
+            }
+
+            last_collected_total += rd->last_collected_value;
+            collected_total += rd->collected_value;
+
+            if(unlikely(rrddim_flag_check(rd, RRDDIM_FLAG_OBSOLETE))) {
+                error("Dimension %s in chart '%s' has the OBSOLETE flag set, but it is collected.", rrddim_name(rd), rrdset_id(st));
+                rrddim_isnot_obsolete(st, rd);
+            }
+        }
     }
+    rrddim_foreach_done(rd);
+    rda_slots = dimensions;
 
-    uint32_t has_reset_value = 0;
+    if (unlikely(st->rrd_memory_mode == RRD_MEMORY_MODE_NONE))
+        goto after_second_database_work;
+
+    rrdset_debug(st, "last_collect_ut = %0.3" NETDATA_DOUBLE_MODIFIER " (last collection time)", (NETDATA_DOUBLE)last_collect_ut/USEC_PER_SEC);
+    rrdset_debug(st, "now_collect_ut  = %0.3" NETDATA_DOUBLE_MODIFIER " (current collection time)", (NETDATA_DOUBLE)now_collect_ut/USEC_PER_SEC);
+    rrdset_debug(st, "last_stored_ut  = %0.3" NETDATA_DOUBLE_MODIFIER " (last updated time)", (NETDATA_DOUBLE)last_stored_ut/USEC_PER_SEC);
+    rrdset_debug(st, "next_store_ut   = %0.3" NETDATA_DOUBLE_MODIFIER " (next interpolation point)", (NETDATA_DOUBLE)next_store_ut/USEC_PER_SEC);
 
     // process all dimensions to calculate their values
     // based on the collected figures only
     // at this stage we do not interpolate anything
-    rrddim_foreach_read(rd, st) {
-        if (rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED))
-            continue;
+    for(dim_id = 0, rda = rda_base ; dim_id < rda_slots ; ++dim_id, ++rda) {
+        rd = rda->rd;
+        if(unlikely(!rd)) continue;
 
         if(unlikely(!rd->updated)) {
             rd->calculated_value = 0;
             continue;
         }
 
-        if(unlikely(rrddim_flag_check(rd, RRDDIM_FLAG_OBSOLETE))) {
-            error("Dimension %s in chart '%s' has the OBSOLETE flag set, but it is collected.", rd->name, st->id);
-            rrddim_isnot_obsolete(st, rd);
-        }
-
-        #ifdef NETDATA_INTERNAL_CHECKS
         rrdset_debug(st, "%s: START "
                 " last_collected_value = " COLLECTED_NUMBER_FORMAT
                 " collected_value = " COLLECTED_NUMBER_FORMAT
                 " last_calculated_value = " NETDATA_DOUBLE_FORMAT
-                " calculated_value = " NETDATA_DOUBLE_FORMAT, rd->name
-                                      , rd->last_collected_value
-                                      , rd->collected_value
-                                      , rd->last_calculated_value
-                                      , rd->calculated_value
+                " calculated_value = " NETDATA_DOUBLE_FORMAT
+                     , rrddim_name(rd)
+                     , rd->last_collected_value
+                     , rd->collected_value
+                     , rd->last_calculated_value
+                     , rd->calculated_value
         );
-        #endif
 
         switch(rd->algorithm) {
             case RRD_ALGORITHM_ABSOLUTE:
@@ -1529,22 +1680,20 @@ after_first_database_work:
                                        * (NETDATA_DOUBLE)rd->multiplier
                                        / (NETDATA_DOUBLE)rd->divisor;
 
-                #ifdef NETDATA_INTERNAL_CHECKS
                 rrdset_debug(st, "%s: CALC ABS/ABS-NO-IN " NETDATA_DOUBLE_FORMAT " = "
                             COLLECTED_NUMBER_FORMAT
                             " * " NETDATA_DOUBLE_FORMAT
-                            " / " NETDATA_DOUBLE_FORMAT, rd->name
+                            " / " NETDATA_DOUBLE_FORMAT
+                          , rrddim_name(rd)
                           , rd->calculated_value
                           , rd->collected_value
                           , (NETDATA_DOUBLE)rd->multiplier
                           , (NETDATA_DOUBLE)rd->divisor
                 );
-                #endif
-
                 break;
 
             case RRD_ALGORITHM_PCENT_OVER_ROW_TOTAL:
-                if(unlikely(!st->collected_total))
+                if(unlikely(!collected_total))
                     rd->calculated_value = 0;
                 else
                     // the percentage of the current value
@@ -1552,19 +1701,16 @@ after_first_database_work:
                     rd->calculated_value =
                             (NETDATA_DOUBLE)100
                             * (NETDATA_DOUBLE)rd->collected_value
-                            / (NETDATA_DOUBLE)st->collected_total;
+                            / (NETDATA_DOUBLE)collected_total;
 
-                #ifdef NETDATA_INTERNAL_CHECKS
                 rrdset_debug(st, "%s: CALC PCENT-ROW " NETDATA_DOUBLE_FORMAT " = 100"
                             " * " COLLECTED_NUMBER_FORMAT
                             " / " COLLECTED_NUMBER_FORMAT
-                          , rd->name
+                          , rrddim_name(rd)
                           , rd->calculated_value
                           , rd->collected_value
-                          , st->collected_total
+                          , collected_total
                 );
-                #endif
-
                 break;
 
             case RRD_ALGORITHM_INCREMENTAL:
@@ -1578,12 +1724,13 @@ after_first_database_work:
                 // It is imperative to set the comparison to uint64_t since type collected_number is signed and
                 // produces wrong results as far as incremental counters are concerned.
                 if(unlikely((uint64_t)rd->last_collected_value > (uint64_t)rd->collected_value)) {
-                    debug(D_RRD_STATS, "%s.%s: RESET or OVERFLOW. Last collected value = " COLLECTED_NUMBER_FORMAT ", current = " COLLECTED_NUMBER_FORMAT
-                          , st->name, rd->name
+                    debug(D_RRD_STATS, "'%s' / '%s': RESET or OVERFLOW. Last collected value = " COLLECTED_NUMBER_FORMAT ", current = " COLLECTED_NUMBER_FORMAT
+                          , rrdset_id(st)
+                          , rrddim_name(rd)
                           , rd->last_collected_value
                           , rd->collected_value);
 
-                    if(!(rrddim_flag_check(rd, RRDDIM_FLAG_DONT_DETECT_RESETS_OR_OVERFLOWS)))
+                    if(!(rrddim_option_check(rd, RRDDIM_OPTION_DONT_DETECT_RESETS_OR_OVERFLOWS)))
                         has_reset_value = 1;
 
                     uint64_t last = (uint64_t)rd->last_collected_value;
@@ -1622,19 +1769,17 @@ after_first_database_work:
                             / (NETDATA_DOUBLE) rd->divisor;
                 }
 
-                #ifdef NETDATA_INTERNAL_CHECKS
                 rrdset_debug(st, "%s: CALC INC PRE " NETDATA_DOUBLE_FORMAT " = ("
                             COLLECTED_NUMBER_FORMAT " - " COLLECTED_NUMBER_FORMAT
                             ")"
                                     " * " NETDATA_DOUBLE_FORMAT
-                            " / " NETDATA_DOUBLE_FORMAT, rd->name
+                            " / " NETDATA_DOUBLE_FORMAT
+                          , rrddim_name(rd)
                           , rd->calculated_value
                           , rd->collected_value, rd->last_collected_value
                           , (NETDATA_DOUBLE)rd->multiplier
                           , (NETDATA_DOUBLE)rd->divisor
                 );
-                #endif
-
                 break;
 
             case RRD_ALGORITHM_PCENT_OVER_DIFF_TOTAL:
@@ -1643,42 +1788,24 @@ after_first_database_work:
                     continue;
                 }
 
-                // if the new is smaller than the old (an overflow, or reset), set the old equal to the new
-                // to reset the calculation (it will give zero as the calculation for this second)
-                if(unlikely(rd->last_collected_value > rd->collected_value)) {
-                    debug(D_RRD_STATS, "%s.%s: RESET or OVERFLOW. Last collected value = " COLLECTED_NUMBER_FORMAT ", current = " COLLECTED_NUMBER_FORMAT
-                          , st->name, rd->name
-                          , rd->last_collected_value
-                          , rd->collected_value
-                    );
-
-                    if(!(rrddim_flag_check(rd, RRDDIM_FLAG_DONT_DETECT_RESETS_OR_OVERFLOWS)))
-                        has_reset_value = 1;
-
-                    rd->last_collected_value = rd->collected_value;
-                }
-
                 // the percentage of the current increment
                 // over the increment of all dimensions together
-                if(unlikely(st->collected_total == st->last_collected_total))
+                if(unlikely(collected_total == last_collected_total))
                     rd->calculated_value = 0;
                 else
                     rd->calculated_value =
                             (NETDATA_DOUBLE)100
                             * (NETDATA_DOUBLE)(rd->collected_value - rd->last_collected_value)
-                            / (NETDATA_DOUBLE)(st->collected_total - st->last_collected_total);
+                            / (NETDATA_DOUBLE)(collected_total - last_collected_total);
 
-                #ifdef NETDATA_INTERNAL_CHECKS
                 rrdset_debug(st, "%s: CALC PCENT-DIFF " NETDATA_DOUBLE_FORMAT " = 100"
                             " * (" COLLECTED_NUMBER_FORMAT " - " COLLECTED_NUMBER_FORMAT ")"
                             " / (" COLLECTED_NUMBER_FORMAT " - " COLLECTED_NUMBER_FORMAT ")"
-                          , rd->name
+                          , rrddim_name(rd)
                           , rd->calculated_value
                           , rd->collected_value, rd->last_collected_value
-                          , st->collected_total, st->last_collected_total
+                          , collected_total, last_collected_total
                 );
-                #endif
-
                 break;
 
             default:
@@ -1686,43 +1813,41 @@ after_first_database_work:
                 // it gets noticed when we add new types
                 rd->calculated_value = 0;
 
-                #ifdef NETDATA_INTERNAL_CHECKS
                 rrdset_debug(st, "%s: CALC " NETDATA_DOUBLE_FORMAT " = 0"
-                          , rd->name
+                          , rrddim_name(rd)
                           , rd->calculated_value
                 );
-                #endif
-
                 break;
         }
 
-        #ifdef NETDATA_INTERNAL_CHECKS
         rrdset_debug(st, "%s: PHASE2 "
                     " last_collected_value = " COLLECTED_NUMBER_FORMAT
                     " collected_value = " COLLECTED_NUMBER_FORMAT
                     " last_calculated_value = " NETDATA_DOUBLE_FORMAT
-                    " calculated_value = " NETDATA_DOUBLE_FORMAT, rd->name
-                                      , rd->last_collected_value
-                                      , rd->collected_value
-                                      , rd->last_calculated_value
-                                      , rd->calculated_value
+                    " calculated_value = " NETDATA_DOUBLE_FORMAT
+                    , rrddim_name(rd)
+                    , rd->last_collected_value
+                    , rd->collected_value
+                    , rd->last_calculated_value
+                    , rd->calculated_value
         );
-        #endif
-
     }
 
     // at this point we have all the calculated values ready
     // it is now time to interpolate values on a second boundary
 
-#ifdef NETDATA_INTERNAL_CHECKS
-    if(unlikely(now_collect_ut < next_store_ut && st->counter_done > 1)) {
-        // this is collected in the same interpolation point
-        rrdset_debug(st, "THIS IS IN THE SAME INTERPOLATION POINT");
-        info("INTERNAL CHECK: host '%s', chart '%s' collection %zu is in the same interpolation point: short by %llu microseconds", st->rrdhost->hostname, st->name, st->counter_done, next_store_ut - now_collect_ut);
-    }
-#endif
-
-    rrdset_done_interpolate(st
+// #ifdef NETDATA_INTERNAL_CHECKS
+//     if(unlikely(now_collect_ut < next_store_ut && st->counter_done > 1)) {
+//         // this is collected in the same interpolation point
+//         rrdset_debug(st, "THIS IS IN THE SAME INTERPOLATION POINT");
+//         info("INTERNAL CHECK: host '%s', chart '%s' collection %zu is in the same interpolation point: short by %llu microseconds", st->rrdhost->hostname, rrdset_name(st), st->counter_done, next_store_ut - now_collect_ut);
+//     }
+// #endif
+
+    rrdset_done_interpolate(
+            st
+            , rda_base
+            , rda_slots
             , update_every_ut
             , last_stored_ut
             , next_store_ut
@@ -1733,54 +1858,41 @@ after_first_database_work:
     );
 
 after_second_database_work:
-    st->last_collected_total  = st->collected_total;
+    for(dim_id = 0, rda = rda_base ; dim_id < rda_slots ; ++dim_id, ++rda) {
+        rd = rda->rd;
+        if(unlikely(!rd)) continue;
 
-#ifdef ENABLE_ACLK
-    time_t mark = now_realtime_sec();
-#endif
-    rrddim_foreach_read(rd, st) {
-        if (rrddim_flag_check(rd, RRDDIM_FLAG_ARCHIVED))
-            continue;
-
-#ifdef ENABLE_ACLK
-        if (likely(!st->state->is_ar_chart)) {
-            if (!rrddim_flag_check(rd, RRDDIM_FLAG_HIDDEN) && likely(rrdset_flag_check(st, RRDSET_FLAG_ACLK)))
-                queue_dimension_to_aclk(rd, calc_dimension_liveness(rd, mark));
-        }
-#endif
         if(unlikely(!rd->updated))
             continue;
 
-        #ifdef NETDATA_INTERNAL_CHECKS
-        rrdset_debug(st, "%s: setting last_collected_value (old: " COLLECTED_NUMBER_FORMAT ") to last_collected_value (new: " COLLECTED_NUMBER_FORMAT ")", rd->name, rd->last_collected_value, rd->collected_value);
-        #endif
+        rrdset_debug(st, "%s: setting last_collected_value (old: " COLLECTED_NUMBER_FORMAT ") to last_collected_value (new: " COLLECTED_NUMBER_FORMAT ")", rrddim_name(rd), rd->last_collected_value, rd->collected_value);
 
         rd->last_collected_value = rd->collected_value;
 
         switch(rd->algorithm) {
             case RRD_ALGORITHM_INCREMENTAL:
                 if(unlikely(!first_entry)) {
-                    #ifdef NETDATA_INTERNAL_CHECKS
-                    rrdset_debug(st, "%s: setting last_calculated_value (old: " NETDATA_DOUBLE_FORMAT
-                        ") to last_calculated_value (new: " NETDATA_DOUBLE_FORMAT ")", rd->name, rd->last_calculated_value + rd->calculated_value, rd->calculated_value);
-                    #endif
+                    rrdset_debug(st, "%s: setting last_calculated_value (old: " NETDATA_DOUBLE_FORMAT ") to "
+                                     "last_calculated_value (new: " NETDATA_DOUBLE_FORMAT ")"
+                        , rrddim_name(rd)
+                        , rd->last_calculated_value + rd->calculated_value
+                        , rd->calculated_value);
 
                     rd->last_calculated_value += rd->calculated_value;
                 }
                 else {
-                    #ifdef NETDATA_INTERNAL_CHECKS
                     rrdset_debug(st, "THIS IS THE FIRST POINT");
-                    #endif
                 }
                 break;
 
             case RRD_ALGORITHM_ABSOLUTE:
             case RRD_ALGORITHM_PCENT_OVER_ROW_TOTAL:
             case RRD_ALGORITHM_PCENT_OVER_DIFF_TOTAL:
-                #ifdef NETDATA_INTERNAL_CHECKS
-                rrdset_debug(st, "%s: setting last_calculated_value (old: " NETDATA_DOUBLE_FORMAT
-                    ") to last_calculated_value (new: " NETDATA_DOUBLE_FORMAT ")", rd->name, rd->last_calculated_value, rd->calculated_value);
-                #endif
+                rrdset_debug(st, "%s: setting last_calculated_value (old: " NETDATA_DOUBLE_FORMAT ") to "
+                                 "last_calculated_value (new: " NETDATA_DOUBLE_FORMAT ")"
+                    , rrddim_name(rd)
+                    , rd->last_calculated_value
+                    , rd->calculated_value);
 
                 rd->last_calculated_value = rd->calculated_value;
                 break;
@@ -1790,19 +1902,17 @@ after_second_database_work:
         rd->collected_value = 0;
         rd->updated = 0;
 
-        #ifdef NETDATA_INTERNAL_CHECKS
         rrdset_debug(st, "%s: END "
                     " last_collected_value = " COLLECTED_NUMBER_FORMAT
                     " collected_value = " COLLECTED_NUMBER_FORMAT
                     " last_calculated_value = " NETDATA_DOUBLE_FORMAT
-                    " calculated_value = " NETDATA_DOUBLE_FORMAT, rd->name
-                                      , rd->last_collected_value
-                                      , rd->collected_value
-                                      , rd->last_calculated_value
-                                      , rd->calculated_value
+                    " calculated_value = " NETDATA_DOUBLE_FORMAT
+                    , rrddim_name(rd)
+                    , rd->last_collected_value
+                    , rd->collected_value
+                    , rd->last_calculated_value
+                    , rd->calculated_value
         );
-        #endif
-
     }
 
     // ALL DONE ABOUT THE DATA UPDATE
@@ -1812,99 +1922,54 @@ after_second_database_work:
         // update the memory mapped files with the latest values
 
         rrdset_memory_file_update(st);
-        rrddim_foreach_read(rd, st) {
+
+        for(dim_id = 0, rda = rda_base; dim_id < rda_slots ; ++dim_id, ++rda) {
+            rd = rda->rd;
+            if(unlikely(!rd)) continue;
             rrddim_memory_file_update(rd);
         }
     }
 
-    // find if there are any obsolete dimensions
-    if(unlikely(rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE_DIMENSIONS))) {
-        rrddim_foreach_read(rd, st)
-            if(unlikely(rrddim_flag_check(rd, RRDDIM_FLAG_OBSOLETE)))
-                break;
+    for(dim_id = 0, rda = rda_base; dim_id < rda_slots ; ++dim_id, ++rda) {
+        rd = rda->rd;
+        if(unlikely(!rd)) continue;
 
-        if(unlikely(rd)) {
-            time_t now = now_realtime_sec();
-
-            RRDDIM *last;
-            // there is a dimension to free
-            // upgrade our read lock to a write lock
-            rrdset_unlock(st);
-            rrdset_wrlock(st);
-
-            for( rd = st->dimensions, last = NULL ; likely(rd) ; ) {
-                if(unlikely(rrddim_flag_check(rd, RRDDIM_FLAG_OBSOLETE) &&  !rrddim_flag_check(rd, RRDDIM_FLAG_ACLK)
-                             && (rd->last_collected_time.tv_sec + rrdset_free_obsolete_time < now))) {
-                    info("Removing obsolete dimension '%s' (%s) of '%s' (%s).", rd->name, rd->id, st->name, st->id);
-
-                    const char *cache_filename = rrddim_cache_filename(rd);
-                    if(cache_filename) {
-                        info("Deleting dimension file '%s'.", cache_filename);
-                        if (unlikely(unlink(cache_filename) == -1))
-                            error("Cannot delete dimension file '%s'", cache_filename);
-                    }
-
-#ifdef ENABLE_DBENGINE
-                    if (rd->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE) {
-                        rrddim_flag_set(rd, RRDDIM_FLAG_ARCHIVED);
-                        while(rd->variables)
-                            rrddimvar_free(rd->variables);
-
-                        rrddim_flag_clear(rd, RRDDIM_FLAG_OBSOLETE);
-                        /* only a collector can mark a chart as obsolete, so we must remove the reference */
-
-                        size_t tiers_available = 0, tiers_said_yes = 0;
-                        for(int tier = 0; tier < storage_tiers ;tier++) {
-                            if(rd->tiers[tier]) {
-                                tiers_available++;
-
-                                if(rd->tiers[tier]->collect_ops.finalize(rd->tiers[tier]->db_collection_handle))
-                                    tiers_said_yes++;
-
-                                rd->tiers[tier]->db_collection_handle = NULL;
-                            }
-                        }
-
-                        if (tiers_available == tiers_said_yes && tiers_said_yes) {
-                            /* This metric has no data and no references */
-                            delete_dimension_uuid(&rd->metric_uuid);
-                        } else {
-                            /* Do not delete this dimension */
-#ifdef ENABLE_ACLK
-                            queue_dimension_to_aclk(rd, calc_dimension_liveness(rd, mark));
-#endif
-                            last = rd;
-                            rd = rd->next;
-                            continue;
-                        }
-                    }
-#endif
-                    if(unlikely(!last)) {
-                        rrddim_free(st, rd);
-                        rd = st->dimensions;
-                        continue;
-                    }
-                    else {
-                        rrddim_free(st, rd);
-                        rd = last->next;
-                        continue;
-                    }
-                }
-
-                last = rd;
-                rd = rd->next;
-            }
-        }
-        else {
-            rrdset_flag_clear(st, RRDSET_FLAG_OBSOLETE_DIMENSIONS);
-        }
+        dictionary_acquired_item_release(st->rrddim_root_index, rda->item);
+        rda->item = NULL;
+        rda->rd = NULL;
     }
 
-    rrdset_unlock(st);
+    rrdcontext_collected_rrdset(st);
 
     netdata_thread_enable_cancelability();
+
+    store_metric_collection_completed();
 }
 
+time_t rrdset_set_update_every(RRDSET *st, time_t update_every) {
+
+    internal_error(true, "RRDSET '%s' switching update every from %d to %d",
+                   rrdset_id(st), (int)st->update_every, (int)update_every);
+
+    time_t prev_update_every = st->update_every;
+    st->update_every = update_every;
+
+    // switch update every to the storage engine
+    RRDDIM *rd;
+    rrddim_foreach_read(rd, st) {
+        for (size_t tier = 0; tier < storage_tiers; tier++) {
+            if (rd->tiers[tier] && rd->tiers[tier]->db_collection_handle)
+                rd->tiers[tier]->collect_ops->change_collection_frequency(rd->tiers[tier]->db_collection_handle, (int)(st->rrdhost->db[tier].tier_grouping * st->update_every));
+        }
+
+        assert(rd->update_every == prev_update_every &&
+               "chart's update every differs from the update every of its dimensions");
+        rd->update_every = st->update_every;
+    }
+    rrddim_foreach_done(rd);
+
+    return prev_update_every;
+}
 
 // ----------------------------------------------------------------------------
 // compatibility layer for RRDSET files v019
@@ -1966,8 +2031,8 @@ struct rrdset_map_save_v019 {
     usec_t usec_since_last_update;                  // NEEDS TO BE UPDATED - maintained on load
     struct timeval last_updated;                    // NEEDS TO BE UPDATED - check to reset all - fixed on load
     struct timeval last_collected_time;             // ignored
-    long long collected_total;                      // NEEDS TO BE UPDATED - maintained on load
-    long long last_collected_total;                 // NEEDS TO BE UPDATED - maintained on load
+    long long collected_total;                      // ignored
+    long long last_collected_total;                 // ignored
     void *rrdfamily;                                // ignored
     void *rrdhost;                                  // ignored
     void *next;                                     // ignored
@@ -1991,8 +2056,6 @@ void rrdset_memory_file_update(RRDSET *st) {
     st_on_file->usec_since_last_update = st->usec_since_last_update;
     st_on_file->last_updated.tv_sec = st->last_updated.tv_sec;
     st_on_file->last_updated.tv_usec = st->last_updated.tv_usec;
-    st_on_file->collected_total = st->collected_total;
-    st_on_file->last_collected_total = st->last_collected_total;
 }
 
 const char *rrdset_cache_filename(RRDSET *st) {
@@ -2008,7 +2071,7 @@ void rrdset_memory_file_free(RRDSET *st) {
     rrdset_memory_file_update(st);
 
     struct rrdset_map_save_v019 *st_on_file = st->st_on_file;
-    munmap(st_on_file, st_on_file->memsize);
+    netdata_munmap(st_on_file, st_on_file->memsize);
 
     // remove the pointers from the RRDDIM
     st->st_on_file = NULL;
@@ -2047,8 +2110,8 @@ bool rrdset_memory_load_or_create_map_save(RRDSET *st, RRD_MEMORY_MODE memory_mo
         info("Initializing file '%s'.", fullfilename);
         memset(st_on_file, 0, size);
     }
-    else if(strncmp(st_on_file->id, st->id, RRD_ID_LENGTH_MAX_V019) != 0) {
-        error("File '%s' contents are not for chart '%s'. Clearing it.", fullfilename, st->id);
+    else if(strncmp(st_on_file->id, rrdset_id(st), RRD_ID_LENGTH_MAX_V019) != 0) {
+        error("File '%s' contents are not for chart '%s'. Clearing it.", fullfilename, rrdset_id(st));
         memset(st_on_file, 0, size);
     }
     else if(st_on_file->memsize != size || st_on_file->entries != st->entries) {
@@ -2084,8 +2147,6 @@ bool rrdset_memory_load_or_create_map_save(RRDSET *st, RRD_MEMORY_MODE memory_mo
     st->usec_since_last_update = st_on_file->usec_since_last_update;
     st->last_updated.tv_sec = st_on_file->last_updated.tv_sec;
     st->last_updated.tv_usec = st_on_file->last_updated.tv_usec;
-    st->collected_total = st_on_file->collected_total;
-    st->last_collected_total = st_on_file->last_collected_total;
 
     // link it to st
     st->st_on_file = st_on_file;
@@ -2094,7 +2155,7 @@ bool rrdset_memory_load_or_create_map_save(RRDSET *st, RRD_MEMORY_MODE memory_mo
     memset(st_on_file, 0, size);
 
     // set the values we need
-    strncpyz(st_on_file->id, st->id, RRD_ID_LENGTH_MAX_V019 + 1);
+    strncpyz(st_on_file->id, rrdset_id(st), RRD_ID_LENGTH_MAX_V019 + 1);
     strcpy(st_on_file->cache_filename, fullfilename);
     strcpy(st_on_file->magic, RRDSET_MAGIC_V019);
     st_on_file->memsize = size;
diff --git a/database/rrdsetvar.c b/database/rrdsetvar.c
index e520764a2..22cf8a1f0 100644
--- a/database/rrdsetvar.c
+++ b/database/rrdsetvar.c
@@ -1,190 +1,293 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
-#define NETDATA_HEALTH_INTERNALS
 #include "rrd.h"
 
-// ----------------------------------------------------------------------------
-// RRDSETVAR management
-// CHART VARIABLES
+typedef struct rrdsetvar {
+    STRING *name;               // variable name
+    void *value;                // we need this to maintain the allocation for custom chart variables
 
-static inline void rrdsetvar_free_variables(RRDSETVAR *rs) {
-    RRDSET *st = rs->rrdset;
+    const RRDVAR_ACQUIRED *rrdvar_local;
+    const RRDVAR_ACQUIRED *rrdvar_family_chart_id;
+    const RRDVAR_ACQUIRED *rrdvar_family_chart_name;
+    const RRDVAR_ACQUIRED *rrdvar_host_chart_id;
+    const RRDVAR_ACQUIRED *rrdvar_host_chart_name;
+
+    RRDVAR_FLAGS flags:24;
+    RRDVAR_TYPE type:8;
+} RRDSETVAR;
+
+// should only be called while the rrdsetvar dict is write locked
+// otherwise, 2+ threads may be setting the same variables at the same time
+static inline void rrdsetvar_free_rrdvars_unsafe(RRDSET *st, RRDSETVAR *rs) {
     RRDHOST *host = st->rrdhost;
 
     // ------------------------------------------------------------------------
     // CHART
-    rrdvar_free(host, &st->rrdvar_root_index, rs->var_local);
-    rs->var_local = NULL;
+
+    if(st->rrdvars) {
+        rrdvar_release_and_del(st->rrdvars, rs->rrdvar_local);
+        rs->rrdvar_local = NULL;
+    }
 
     // ------------------------------------------------------------------------
     // FAMILY
-    rrdvar_free(host, &st->rrdfamily->rrdvar_root_index, rs->var_family);
-    rs->var_family = NULL;
 
-    rrdvar_free(host, &st->rrdfamily->rrdvar_root_index, rs->var_family_name);
-    rs->var_family_name = NULL;
+    if(st->rrdfamily) {
+        rrdvar_release_and_del(rrdfamily_rrdvars_dict(st->rrdfamily), rs->rrdvar_family_chart_id);
+        rs->rrdvar_family_chart_id = NULL;
+
+        rrdvar_release_and_del(rrdfamily_rrdvars_dict(st->rrdfamily), rs->rrdvar_family_chart_name);
+        rs->rrdvar_family_chart_name = NULL;
+    }
 
     // ------------------------------------------------------------------------
     // HOST
-    rrdvar_free(host, &host->rrdvar_root_index, rs->var_host);
-    rs->var_host = NULL;
 
-    rrdvar_free(host, &host->rrdvar_root_index, rs->var_host_name);
-    rs->var_host_name = NULL;
+    if(host->rrdvars && host->health_enabled) {
+        rrdvar_release_and_del(host->rrdvars, rs->rrdvar_host_chart_id);
+        rs->rrdvar_host_chart_id = NULL;
 
-    // ------------------------------------------------------------------------
-    // KEYS
-    freez(rs->key_fullid);
-    rs->key_fullid = NULL;
-
-    freez(rs->key_fullname);
-    rs->key_fullname = NULL;
+        rrdvar_release_and_del(host->rrdvars, rs->rrdvar_host_chart_name);
+        rs->rrdvar_host_chart_name = NULL;
+    }
 }
 
-static inline void rrdsetvar_create_variables(RRDSETVAR *rs) {
-    RRDSET *st = rs->rrdset;
+// should only be called while the rrdsetvar dict is write locked
+// otherwise, 2+ threads may be setting the same variables at the same time
+static inline void rrdsetvar_update_rrdvars_unsafe(RRDSET *st, RRDSETVAR *rs) {
     RRDHOST *host = st->rrdhost;
 
-    RRDVAR_OPTIONS options = rs->options;
-    if(rs->options & RRDVAR_OPTION_ALLOCATED)
-        options &= ~ RRDVAR_OPTION_ALLOCATED;
+    RRDVAR_FLAGS options = rs->flags;
+    options &= ~RRDVAR_OPTIONS_REMOVED_WHEN_PROPAGATING_TO_RRDVAR;
 
     // ------------------------------------------------------------------------
     // free the old ones (if any)
 
-    rrdsetvar_free_variables(rs);
+    rrdsetvar_free_rrdvars_unsafe(st, rs);
 
     // ------------------------------------------------------------------------
     // KEYS
 
     char buffer[RRDVAR_MAX_LENGTH + 1];
-    snprintfz(buffer, RRDVAR_MAX_LENGTH, "%s.%s", st->id, rs->variable);
-    rs->key_fullid = strdupz(buffer);
+    snprintfz(buffer, RRDVAR_MAX_LENGTH, "%s.%s", rrdset_id(st), string2str(rs->name));
+    STRING *key_chart_id = string_strdupz(buffer);
 
-    snprintfz(buffer, RRDVAR_MAX_LENGTH, "%s.%s", st->name, rs->variable);
-    rs->key_fullname = strdupz(buffer);
+    snprintfz(buffer, RRDVAR_MAX_LENGTH, "%s.%s", rrdset_name(st), string2str(rs->name));
+    STRING *key_chart_name = string_strdupz(buffer);
 
     // ------------------------------------------------------------------------
     // CHART
-    rs->var_local       = rrdvar_create_and_index("local",  &st->rrdvar_root_index, rs->variable, rs->type, options, rs->value);
+
+    if(st->rrdvars) {
+        rs->rrdvar_local = rrdvar_add_and_acquire("local", st->rrdvars, rs->name, rs->type, options, rs->value);
+    }
 
     // ------------------------------------------------------------------------
     // FAMILY
-    rs->var_family      = rrdvar_create_and_index("family", &st->rrdfamily->rrdvar_root_index, rs->key_fullid,   rs->type, options, rs->value);
-    rs->var_family_name = rrdvar_create_and_index("family", &st->rrdfamily->rrdvar_root_index, rs->key_fullname, rs->type, options, rs->value);
+
+    if(st->rrdfamily) {
+        rs->rrdvar_family_chart_id = rrdvar_add_and_acquire("family", rrdfamily_rrdvars_dict(st->rrdfamily), key_chart_id, rs->type, options, rs->value);
+        rs->rrdvar_family_chart_name = rrdvar_add_and_acquire("family", rrdfamily_rrdvars_dict(st->rrdfamily), key_chart_name, rs->type, options, rs->value);
+    }
 
     // ------------------------------------------------------------------------
     // HOST
-    rs->var_host        = rrdvar_create_and_index("host",   &host->rrdvar_root_index, rs->key_fullid,   rs->type, options, rs->value);
-    rs->var_host_name   = rrdvar_create_and_index("host",   &host->rrdvar_root_index, rs->key_fullname, rs->type, options, rs->value);
-}
 
-RRDSETVAR *rrdsetvar_create(RRDSET *st, const char *variable, RRDVAR_TYPE type, void *value, RRDVAR_OPTIONS options) {
-    debug(D_VARIABLES, "RRDVARSET create for chart id '%s' name '%s' with variable name '%s'", st->id, st->name, variable);
-    RRDSETVAR *rs = (RRDSETVAR *)callocz(1, sizeof(RRDSETVAR));
+    if(host->rrdvars && host->health_enabled) {
+        rs->rrdvar_host_chart_id = rrdvar_add_and_acquire("host", host->rrdvars, key_chart_id, rs->type, options, rs->value);
+        rs->rrdvar_host_chart_name = rrdvar_add_and_acquire("host", host->rrdvars, key_chart_name, rs->type, options, rs->value);
+    }
 
-    rs->variable = strdupz(variable);
-    rs->hash = simple_hash(rs->variable);
-    rs->type = type;
-    rs->value = value;
-    rs->options = options;
-    rs->rrdset = st;
+    // free the keys
+    string_freez(key_chart_id);
+    string_freez(key_chart_name);
+}
 
-    rs->next = st->variables;
-    st->variables = rs;
+static void rrdsetvar_free_value_unsafe(RRDSETVAR *rs) {
+    if(rs->flags & RRDVAR_FLAG_ALLOCATED) {
+        void *old = rs->value;
+        rs->value = NULL;
+        rs->flags &= ~RRDVAR_FLAG_ALLOCATED;
+        freez(old);
+    }
+}
 
-    rrdsetvar_create_variables(rs);
+static void rrdsetvar_set_value_unsafe(RRDSETVAR *rs, void *new_value) {
+    rrdsetvar_free_value_unsafe(rs);
 
-    return rs;
+    if(new_value)
+        rs->value = new_value;
+    else {
+        NETDATA_DOUBLE *n = mallocz(sizeof(NETDATA_DOUBLE));
+        *n = NAN;
+        rs->value = n;
+        rs->flags |= RRDVAR_FLAG_ALLOCATED;
+    }
 }
 
-void rrdsetvar_rename_all(RRDSET *st) {
-    debug(D_VARIABLES, "RRDSETVAR rename for chart id '%s' name '%s'", st->id, st->name);
+struct rrdsetvar_constructor {
+    RRDSET *rrdset;
+    const char *name;
+    void *value;
+    RRDVAR_FLAGS flags :16;
+    RRDVAR_TYPE type:8;
+};
 
-    RRDSETVAR *rs;
-    for(rs = st->variables; rs ; rs = rs->next)
-        rrdsetvar_create_variables(rs);
+static void rrdsetvar_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdsetvar, void *constructor_data) {
+    RRDSETVAR *rs = rrdsetvar;
+    struct rrdsetvar_constructor *ctr = constructor_data;
+
+    ctr->flags &= ~RRDVAR_OPTIONS_REMOVED_ON_NEW_OBJECTS;
 
-    rrdsetcalc_link_matching(st);
+    rs->name = string_strdupz(ctr->name);
+    rs->type = ctr->type;
+    rs->flags = ctr->flags;
+    rrdsetvar_set_value_unsafe(rs, ctr->value);
+
+    // create the rrdvariables while we are having a write lock to the dictionary
+    rrdsetvar_update_rrdvars_unsafe(ctr->rrdset, rs);
 }
 
-void rrdsetvar_free(RRDSETVAR *rs) {
-    RRDSET *st = rs->rrdset;
-    debug(D_VARIABLES, "RRDSETVAR free for chart id '%s' name '%s', variable '%s'", st->id, st->name, rs->variable);
+static bool rrdsetvar_conflict_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdsetvar, void *new_rrdsetvar __maybe_unused, void *constructor_data) {
+    RRDSETVAR *rs = rrdsetvar;
+    struct rrdsetvar_constructor *ctr = constructor_data;
 
-    if(st->variables == rs) {
-        st->variables = rs->next;
-    }
-    else {
-        RRDSETVAR *t;
-        for (t = st->variables; t && t->next != rs; t = t->next);
-        if(!t) error("RRDSETVAR '%s' not found in chart '%s' variables linked list", rs->key_fullname, st->id);
-        else t->next = rs->next;
+    ctr->flags &= ~RRDVAR_OPTIONS_REMOVED_ON_NEW_OBJECTS;
+
+    RRDVAR_FLAGS options = rs->flags;
+    options &= ~RRDVAR_OPTIONS_REMOVED_ON_NEW_OBJECTS;
+
+    if(((ctr->value == NULL && rs->value != NULL && rs->flags & RRDVAR_FLAG_ALLOCATED) || (rs->value == ctr->value))
+        && ctr->flags == options && rs->type == ctr->type) {
+        // don't reset it - everything is the same, or as it should...
+        return false;
     }
 
-    rrdsetvar_free_variables(rs);
+    internal_error(true, "RRDSETVAR: resetting variable '%s' of chart '%s' of host '%s', options from 0x%x to 0x%x, type from %d to %d",
+                   string2str(rs->name), rrdset_id(ctr->rrdset), rrdhost_hostname(ctr->rrdset->rrdhost),
+                   options, ctr->flags, rs->type, ctr->type);
 
-    freez(rs->variable);
+    rrdsetvar_free_value_unsafe(rs); // we are going to change the options, so free it before setting it
+    rs->flags = ctr->flags;
+    rs->type = ctr->type;
+    rrdsetvar_set_value_unsafe(rs, ctr->value);
 
-    if(rs->options & RRDVAR_OPTION_ALLOCATED)
-        freez(rs->value);
+    // recreate the rrdvariables while we are having a write lock to the dictionary
+    rrdsetvar_update_rrdvars_unsafe(ctr->rrdset, rs);
+    return true;
+}
+
+static void rrdsetvar_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdsetvar, void *rrdset __maybe_unused) {
+    RRDSET *st = rrdset;
+    RRDSETVAR *rs = rrdsetvar;
 
-    freez(rs);
+    rrdsetvar_free_rrdvars_unsafe(st, rs);
+    rrdsetvar_free_value_unsafe(rs);
+    string_freez(rs->name);
+    rs->name = NULL;
 }
 
-// --------------------------------------------------------------------------------------------------------------------
-// custom chart variables
+void rrdsetvar_index_init(RRDSET *st) {
+    if(!st->rrdsetvar_root_index) {
+        st->rrdsetvar_root_index = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
 
-RRDSETVAR *rrdsetvar_custom_chart_variable_create(RRDSET *st, const char *name) {
-    RRDHOST *host = st->rrdhost;
+        dictionary_register_insert_callback(st->rrdsetvar_root_index, rrdsetvar_insert_callback, NULL);
+        dictionary_register_conflict_callback(st->rrdsetvar_root_index, rrdsetvar_conflict_callback, NULL);
+        dictionary_register_delete_callback(st->rrdsetvar_root_index, rrdsetvar_delete_callback, st);
+    }
+}
 
-    char *n = strdupz(name);
-    rrdvar_fix_name(n);
-    uint32_t hash = simple_hash(n);
+void rrdsetvar_index_destroy(RRDSET *st) {
+    dictionary_destroy(st->rrdsetvar_root_index);
+    st->rrdsetvar_root_index = NULL;
+}
 
-    rrdset_wrlock(st);
+const RRDSETVAR_ACQUIRED *rrdsetvar_add_and_acquire(RRDSET *st, const char *name, RRDVAR_TYPE type, void *value, RRDVAR_FLAGS flags) {
+    struct rrdsetvar_constructor tmp = {
+        .name = name,
+        .type = type,
+        .value = value,
+        .flags = flags,
+        .rrdset = st,
+    };
+
+    const RRDSETVAR_ACQUIRED *rsa = (const RRDSETVAR_ACQUIRED *)dictionary_set_and_acquire_item_advanced(st->rrdsetvar_root_index, name, -1, NULL, sizeof(RRDSETVAR), &tmp);
+    return rsa;
+}
+
+void rrdsetvar_add_and_leave_released(RRDSET *st, const char *name, RRDVAR_TYPE type, void *value, RRDVAR_FLAGS flags) {
+    const RRDSETVAR_ACQUIRED *rsa = rrdsetvar_add_and_acquire(st, name, type, value, flags);
+    dictionary_acquired_item_release(st->rrdsetvar_root_index, (const DICTIONARY_ITEM *)rsa);
+}
+
+void rrdsetvar_rename_all(RRDSET *st) {
+    debug(D_VARIABLES, "RRDSETVAR rename for chart id '%s' name '%s'", rrdset_id(st), rrdset_name(st));
 
-    // find it
     RRDSETVAR *rs;
-    for(rs = st->variables; rs ; rs = rs->next) {
-        if(hash == rs->hash && strcmp(n, rs->variable) == 0) {
-            rrdset_unlock(st);
-            if(rs->options & RRDVAR_OPTION_CUSTOM_CHART_VAR) {
-                freez(n);
-                return rs;
-            }
-            else {
-                error("RRDSETVAR: custom variable '%s' on chart '%s' of host '%s', conflicts with an internal chart variable", n, st->id, host->hostname);
-                freez(n);
-                return NULL;
-            }
-        }
+    dfe_start_write(st->rrdsetvar_root_index, rs) {
+        // should only be called while the rrdsetvar dict is write locked
+        rrdsetvar_update_rrdvars_unsafe(st, rs);
     }
+    dfe_done(rs);
 
-    // not found, allocate one
+    rrdcalc_link_matching_alerts_to_rrdset(st);
+}
 
-    NETDATA_DOUBLE *v = mallocz(sizeof(NETDATA_DOUBLE));
-    *v = NAN;
+void rrdsetvar_release_and_delete_all(RRDSET *st) {
+    RRDSETVAR *rs;
+    dfe_start_write(st->rrdsetvar_root_index, rs) {
+        dictionary_del_advanced(st->rrdsetvar_root_index, string2str(rs->name), (ssize_t)string_strlen(rs->name) + 1);
+    }
+    dfe_done(rs);
+}
 
-    rs = rrdsetvar_create(st, n, RRDVAR_TYPE_CALCULATED, v, RRDVAR_OPTION_ALLOCATED|RRDVAR_OPTION_CUSTOM_CHART_VAR);
-    rrdset_unlock(st);
+void rrdsetvar_release(DICTIONARY *dict, const RRDSETVAR_ACQUIRED *rsa) {
+    dictionary_acquired_item_release(dict, (const DICTIONARY_ITEM *)rsa);
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+// custom chart variables
 
-    freez(n);
+const RRDSETVAR_ACQUIRED *rrdsetvar_custom_chart_variable_add_and_acquire(RRDSET *st, const char *name) {
+    STRING *name_string = rrdvar_name_to_string(name);
+    const RRDSETVAR_ACQUIRED *rs = rrdsetvar_add_and_acquire(st, string2str(name_string), RRDVAR_TYPE_CALCULATED, NULL, RRDVAR_FLAG_CUSTOM_CHART_VAR);
+    string_freez(name_string);
     return rs;
 }
 
-void rrdsetvar_custom_chart_variable_set(RRDSETVAR *rs, NETDATA_DOUBLE value) {
-    if(rs->type != RRDVAR_TYPE_CALCULATED || !(rs->options & RRDVAR_OPTION_CUSTOM_CHART_VAR) || !(rs->options & RRDVAR_OPTION_ALLOCATED)) {
+void rrdsetvar_custom_chart_variable_set(RRDSET *st, const RRDSETVAR_ACQUIRED *rsa, NETDATA_DOUBLE value) {
+    if(!rsa) return;
+
+    RRDSETVAR *rs = dictionary_acquired_item_value((const DICTIONARY_ITEM *)rsa);
+
+    if(rs->type != RRDVAR_TYPE_CALCULATED || !(rs->flags & RRDVAR_FLAG_CUSTOM_CHART_VAR) || !(rs->flags & RRDVAR_FLAG_ALLOCATED)) {
         error("RRDSETVAR: requested to set variable '%s' of chart '%s' on host '%s' to value " NETDATA_DOUBLE_FORMAT
-            " but the variable is not a custom chart one.", rs->variable, rs->rrdset->id, rs->rrdset->rrdhost->hostname, value);
+            " but the variable is not a custom chart one (it has options 0x%x, value pointer %p). Ignoring request.", string2str(rs->name), rrdset_id(st), rrdhost_hostname(st->rrdhost), value, (uint32_t)rs->flags, rs->value);
     }
     else {
         NETDATA_DOUBLE *v = rs->value;
         if(*v != value) {
             *v = value;
+            rrdset_flag_set(st, RRDSET_FLAG_UPSTREAM_SEND_VARIABLES);
+        }
+    }
+}
+
+void rrdsetvar_print_to_streaming_custom_chart_variables(RRDSET *st, BUFFER *wb) {
+    rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_SEND_VARIABLES);
 
-            // mark the chart to be sent upstream
-            rrdset_flag_clear(rs->rrdset, RRDSET_FLAG_UPSTREAM_EXPOSED);
+    // send the chart local custom variables
+    RRDSETVAR *rs;
+    dfe_start_read(st->rrdsetvar_root_index, rs) {
+        if(unlikely(rs->type == RRDVAR_TYPE_CALCULATED && rs->flags & RRDVAR_FLAG_CUSTOM_CHART_VAR)) {
+            NETDATA_DOUBLE *value = (NETDATA_DOUBLE *) rs->value;
+
+            buffer_sprintf(wb
+                , "VARIABLE CHART %s = " NETDATA_DOUBLE_FORMAT "\n"
+                , string2str(rs->name)
+                , *value
+            );
         }
     }
+    dfe_done(rs);
 }
diff --git a/database/rrdsetvar.h b/database/rrdsetvar.h
index 37f4da959..0c2e66712 100644
--- a/database/rrdsetvar.h
+++ b/database/rrdsetvar.h
@@ -11,34 +11,20 @@
 // This means, there will be no speed penalty for using
 // these variables
 
-struct rrdsetvar {
-    char *variable;                 // variable name
-    uint32_t hash;                  // variable name hash
+void rrdsetvar_index_init(RRDSET *st);
+void rrdsetvar_index_destroy(RRDSET *st);
+void rrdsetvar_release_and_delete_all(RRDSET *st);
 
-    char *key_fullid;               // chart type.chart id.variable
-    char *key_fullname;             // chart type.chart name.variable
+#define rrdsetvar_custom_chart_variable_release(st, rsa) rrdsetvar_release((st)->rrdsetvar_root_index, rsa)
+void rrdsetvar_release(DICTIONARY *dict, const RRDSETVAR_ACQUIRED *rsa);
 
-    RRDVAR_TYPE type;
-    void *value;
+const RRDSETVAR_ACQUIRED *rrdsetvar_custom_chart_variable_add_and_acquire(RRDSET *st, const char *name);
+void rrdsetvar_custom_chart_variable_set(RRDSET *st, const RRDSETVAR_ACQUIRED *rsa, NETDATA_DOUBLE value);
 
-    RRDVAR_OPTIONS options;
+void rrdsetvar_rename_all(RRDSET *st);
+const RRDSETVAR_ACQUIRED *rrdsetvar_add_and_acquire(RRDSET *st, const char *name, RRDVAR_TYPE type, void *value, RRDVAR_FLAGS flags);
+void rrdsetvar_add_and_leave_released(RRDSET *st, const char *name, RRDVAR_TYPE type, void *value, RRDVAR_FLAGS flags);
 
-    RRDVAR *var_local;
-    RRDVAR *var_family;
-    RRDVAR *var_host;
-    RRDVAR *var_family_name;
-    RRDVAR *var_host_name;
-
-    struct rrdset *rrdset;
-
-    struct rrdsetvar *next;
-};
-
-extern RRDSETVAR *rrdsetvar_custom_chart_variable_create(RRDSET *st, const char *name);
-extern void rrdsetvar_custom_chart_variable_set(RRDSETVAR *rv, NETDATA_DOUBLE value);
-
-extern void rrdsetvar_rename_all(RRDSET *st);
-extern RRDSETVAR *rrdsetvar_create(RRDSET *st, const char *variable, RRDVAR_TYPE type, void *value, RRDVAR_OPTIONS options);
-extern void rrdsetvar_free(RRDSETVAR *rs);
+void rrdsetvar_print_to_streaming_custom_chart_variables(RRDSET *st, BUFFER *wb);
 
 #endif //NETDATA_RRDSETVAR_H
diff --git a/database/rrdvar.c b/database/rrdvar.c
index d4dda1079..28be4f6a1 100644
--- a/database/rrdvar.c
+++ b/database/rrdvar.c
@@ -1,8 +1,19 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
-#define NETDATA_HEALTH_INTERNALS
 #include "rrd.h"
 
+// the variables as stored in the variables indexes
+// there are 3 indexes:
+// 1. at each chart   (RRDSET.rrdvar_root_index)
+// 2. at each context (RRDFAMILY.rrdvar_root_index)
+// 3. at each host    (RRDHOST.rrdvar_root_index)
+typedef struct rrdvar {
+    STRING *name;
+    void *value;
+    RRDVAR_FLAGS flags:24;
+    RRDVAR_TYPE type:8;
+} RRDVAR;
+
 // ----------------------------------------------------------------------------
 // RRDVAR management
 
@@ -20,168 +31,153 @@ inline int rrdvar_fix_name(char *variable) {
     return fixed;
 }
 
-int rrdvar_compare(void* a, void* b) {
-    if(((RRDVAR *)a)->hash < ((RRDVAR *)b)->hash) return -1;
-    else if(((RRDVAR *)a)->hash > ((RRDVAR *)b)->hash) return 1;
-    else return strcmp(((RRDVAR *)a)->name, ((RRDVAR *)b)->name);
+inline STRING *rrdvar_name_to_string(const char *name) {
+    char *variable = strdupz(name);
+    rrdvar_fix_name(variable);
+    STRING *name_string = string_strdupz(variable);
+    freez(variable);
+    return name_string;
 }
 
-static inline RRDVAR *rrdvar_index_add(avl_tree_lock *tree, RRDVAR *rv) {
-    RRDVAR *ret = (RRDVAR *)avl_insert_lock(tree, (avl_t *)(rv));
-    if(ret != rv)
-        debug(D_VARIABLES, "Request to insert RRDVAR '%s' into index failed. Already exists.", rv->name);
+struct rrdvar_constructor {
+    STRING *name;
+    void *value;
+    RRDVAR_FLAGS options:16;
+    RRDVAR_TYPE type:8;
 
-    return ret;
-}
+    enum {
+        RRDVAR_REACT_NONE    = 0,
+        RRDVAR_REACT_NEW     = (1 << 0),
+    } react_action;
+};
+
+static void rrdvar_insert_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdvar, void *constructor_data) {
+    RRDVAR *rv = rrdvar;
+    struct rrdvar_constructor *ctr = constructor_data;
 
-static inline RRDVAR *rrdvar_index_del(avl_tree_lock *tree, RRDVAR *rv) {
-    RRDVAR *ret = (RRDVAR *)avl_remove_lock(tree, (avl_t *)(rv));
-    if(!ret)
-        error("Request to remove RRDVAR '%s' from index failed. Not Found.", rv->name);
+    ctr->options &= ~RRDVAR_OPTIONS_REMOVED_ON_NEW_OBJECTS;
 
-    return ret;
+    rv->name = string_dup(ctr->name);
+    rv->type = ctr->type;
+    rv->flags = ctr->options;
+
+    if(!ctr->value) {
+        NETDATA_DOUBLE *v = mallocz(sizeof(NETDATA_DOUBLE));
+        *v = NAN;
+        rv->value = v;
+        rv->flags |= RRDVAR_FLAG_ALLOCATED;
+    }
+    else
+        rv->value = ctr->value;
+
+    ctr->react_action = RRDVAR_REACT_NEW;
 }
 
-static inline RRDVAR *rrdvar_index_find(avl_tree_lock *tree, const char *name, uint32_t hash) {
-    RRDVAR tmp;
-    tmp.name = (char *)name;
-    tmp.hash = (hash)?hash:simple_hash(tmp.name);
+static void rrdvar_delete_callback(const DICTIONARY_ITEM *item __maybe_unused, void *rrdvar, void *nothing __maybe_unused) {
+    RRDVAR *rv = rrdvar;
 
-    return (RRDVAR *)avl_search_lock(tree, (avl_t *)&tmp);
+    if(rv->flags & RRDVAR_FLAG_ALLOCATED)
+        freez(rv->value);
+
+    string_freez(rv->name);
+    rv->name = NULL;
 }
 
-inline void rrdvar_free(RRDHOST *host, avl_tree_lock *tree, RRDVAR *rv) {
-    (void)host;
+DICTIONARY *rrdvariables_create(void) {
+    DICTIONARY *dict = dictionary_create(DICT_OPTION_DONT_OVERWRITE_VALUE);
 
-    if(!rv) return;
+    dictionary_register_insert_callback(dict, rrdvar_insert_callback, NULL);
+    dictionary_register_delete_callback(dict, rrdvar_delete_callback, NULL);
 
-    if(tree) {
-        debug(D_VARIABLES, "Deleting variable '%s'", rv->name);
-        if(unlikely(!rrdvar_index_del(tree, rv)))
-            error("RRDVAR: Attempted to delete variable '%s' from host '%s', but it is not found.", rv->name, host->hostname);
-    }
+    return dict;
+}
 
-    if(rv->options & RRDVAR_OPTION_ALLOCATED)
-        freez(rv->value);
+void rrdvariables_destroy(DICTIONARY *dict) {
+    dictionary_destroy(dict);
+}
 
-    freez(rv->name);
-    freez(rv);
+static inline const RRDVAR_ACQUIRED *rrdvar_get_and_acquire(DICTIONARY *dict, STRING *name) {
+    return (const RRDVAR_ACQUIRED *)dictionary_get_and_acquire_item_advanced(dict, string2str(name), (ssize_t)string_strlen(name) + 1);
 }
 
-inline RRDVAR *rrdvar_create_and_index(const char *scope __maybe_unused, avl_tree_lock *tree, const char *name,
-                                       RRDVAR_TYPE type, RRDVAR_OPTIONS options, void *value) {
-    char *variable = strdupz(name);
-    rrdvar_fix_name(variable);
-    uint32_t hash = simple_hash(variable);
-
-    RRDVAR *rv = rrdvar_index_find(tree, variable, hash);
-    if(unlikely(!rv)) {
-        debug(D_VARIABLES, "Variable '%s' not found in scope '%s'. Creating a new one.", variable, scope);
-
-        rv = callocz(1, sizeof(RRDVAR));
-        rv->name = variable;
-        rv->hash = hash;
-        rv->type = type;
-        rv->options = options;
-        rv->value = value;
-        rv->last_updated = now_realtime_sec();
-
-        RRDVAR *ret = rrdvar_index_add(tree, rv);
-        if(unlikely(ret != rv)) {
-            debug(D_VARIABLES, "Variable '%s' in scope '%s' already exists", variable, scope);
-            freez(rv);
-            freez(variable);
-            rv = NULL;
-        }
-        else
-            debug(D_VARIABLES, "Variable '%s' created in scope '%s'", variable, scope);
-    }
-    else {
-        debug(D_VARIABLES, "Variable '%s' is already found in scope '%s'.", variable, scope);
+inline void rrdvar_release_and_del(DICTIONARY *dict, const RRDVAR_ACQUIRED *rva) {
+    if(unlikely(!dict || !rva)) return;
 
-        // already exists
-        freez(variable);
+    RRDVAR *rv = dictionary_acquired_item_value((const DICTIONARY_ITEM *)rva);
 
-        // this is important
-        // it must return NULL - not the existing variable - or double-free will happen
-        rv = NULL;
-    }
+    dictionary_del_advanced(dict, string2str(rv->name), (ssize_t)string_strlen(rv->name) + 1);
 
-    return rv;
+    dictionary_acquired_item_release(dict, (const DICTIONARY_ITEM *)rva);
 }
 
-void rrdvar_free_remaining_variables(RRDHOST *host, avl_tree_lock *tree_lock) {
-    // This is not bullet proof - avl should support some means to destroy it
-    // with a callback for each item already in the index
+inline const RRDVAR_ACQUIRED *rrdvar_add_and_acquire(const char *scope __maybe_unused, DICTIONARY *dict, STRING *name, RRDVAR_TYPE type, RRDVAR_FLAGS options, void *value) {
+    if(unlikely(!dict || !name)) return NULL;
 
-    RRDVAR *rv, *last = NULL;
-    while((rv = (RRDVAR *)tree_lock->avl_tree.root)) {
-        if(unlikely(rv == last)) {
-            error("RRDVAR: INTERNAL ERROR: Cannot cleanup tree of RRDVARs");
-            break;
-        }
-        last = rv;
-        rrdvar_free(host, tree_lock, rv);
-    }
+    struct rrdvar_constructor tmp = {
+        .name = name,
+        .value = value,
+        .type = type,
+        .options = options,
+        .react_action = RRDVAR_REACT_NONE,
+    };
+    return (const RRDVAR_ACQUIRED *)dictionary_set_and_acquire_item_advanced(dict, string2str(name), (ssize_t)string_strlen(name) + 1, NULL, sizeof(RRDVAR), &tmp);
+}
+
+void rrdvar_delete_all(DICTIONARY *dict) {
+    dictionary_flush(dict);
 }
 
+
 // ----------------------------------------------------------------------------
 // CUSTOM HOST VARIABLES
 
-inline int rrdvar_callback_for_all_host_variables(RRDHOST *host, int (*callback)(void * /*rrdvar*/, void * /*data*/), void *data) {
-    return avl_traverse_lock(&host->rrdvar_root_index, callback, data);
+inline int rrdvar_walkthrough_read(DICTIONARY *dict, int (*callback)(const DICTIONARY_ITEM *item, void *rrdvar, void *data), void *data) {
+    if(unlikely(!dict)) return 0;  // when health is not enabled
+    return dictionary_walkthrough_read(dict, callback, data);
 }
 
-static RRDVAR *rrdvar_custom_variable_create(const char *scope, avl_tree_lock *tree_lock, const char *name) {
-    NETDATA_DOUBLE *v = callocz(1, sizeof(NETDATA_DOUBLE));
-    *v = NAN;
-
-    RRDVAR *rv = rrdvar_create_and_index(scope, tree_lock, name, RRDVAR_TYPE_CALCULATED, RRDVAR_OPTION_CUSTOM_HOST_VAR|RRDVAR_OPTION_ALLOCATED, v);
-    if(unlikely(!rv)) {
-        freez(v);
-        debug(D_VARIABLES, "Requested variable '%s' already exists - possibly 2 plugins are updating it at the same time.", name);
+const RRDVAR_ACQUIRED *rrdvar_custom_host_variable_add_and_acquire(RRDHOST *host, const char *name) {
+    DICTIONARY *dict = host->rrdvars;
+    if(unlikely(!dict)) return NULL; // when health is not enabled
 
-        char *variable = strdupz(name);
-        rrdvar_fix_name(variable);
-        uint32_t hash = simple_hash(variable);
+    STRING *name_string = rrdvar_name_to_string(name);
 
-        // find the existing one to return it
-        rv = rrdvar_index_find(tree_lock, variable, hash);
+    const RRDVAR_ACQUIRED *rva = rrdvar_add_and_acquire("host", dict, name_string, RRDVAR_TYPE_CALCULATED, RRDVAR_FLAG_CUSTOM_HOST_VAR, NULL);
 
-        freez(variable);
-    }
-
-    return rv;
+    string_freez(name_string);
+    return rva;
 }
 
-RRDVAR *rrdvar_custom_host_variable_create(RRDHOST *host, const char *name) {
-    return rrdvar_custom_variable_create("host", &host->rrdvar_root_index, name);
-}
+void rrdvar_custom_host_variable_set(RRDHOST *host, const RRDVAR_ACQUIRED *rva, NETDATA_DOUBLE value) {
+    if(unlikely(!host->rrdvars || !rva)) return; // when health is not enabled
 
-void rrdvar_custom_host_variable_set(RRDHOST *host, RRDVAR *rv, NETDATA_DOUBLE value) {
-    if(rv->type != RRDVAR_TYPE_CALCULATED || !(rv->options & RRDVAR_OPTION_CUSTOM_HOST_VAR) || !(rv->options & RRDVAR_OPTION_ALLOCATED))
-        error("requested to set variable '%s' to value " NETDATA_DOUBLE_FORMAT " but the variable is not a custom one.", rv->name, value);
+    if(rrdvar_type(rva) != RRDVAR_TYPE_CALCULATED || !(rrdvar_flags(rva) & (RRDVAR_FLAG_CUSTOM_HOST_VAR | RRDVAR_FLAG_ALLOCATED)))
+        error("requested to set variable '%s' to value " NETDATA_DOUBLE_FORMAT " but the variable is not a custom one.", rrdvar_name(rva), value);
     else {
+        RRDVAR *rv = dictionary_acquired_item_value((const DICTIONARY_ITEM *)rva);
         NETDATA_DOUBLE *v = rv->value;
         if(*v != value) {
             *v = value;
 
-            rv->last_updated = now_realtime_sec();
-
             // if the host is streaming, send this variable upstream immediately
-            rrdpush_sender_send_this_host_variable_now(host, rv);
+            rrdpush_sender_send_this_host_variable_now(host, rva);
         }
     }
 }
 
-int foreach_host_variable_callback(RRDHOST *host, int (*callback)(RRDVAR * /*rv*/, void * /*data*/), void *data) {
-    return avl_traverse_lock(&host->rrdvar_root_index, (int (*)(void *, void *))callback, data);
+void rrdvar_release(DICTIONARY *dict, const RRDVAR_ACQUIRED *rva) {
+    if(unlikely(!dict || !rva)) return;  // when health is not enabled
+    dictionary_acquired_item_release(dict, (const DICTIONARY_ITEM *)rva);
 }
 
 // ----------------------------------------------------------------------------
 // RRDVAR lookup
 
-NETDATA_DOUBLE rrdvar2number(RRDVAR *rv) {
+NETDATA_DOUBLE rrdvar2number(const RRDVAR_ACQUIRED *rva) {
+    if(unlikely(!rva)) return NAN;
+
+    RRDVAR *rv = dictionary_acquired_item_value((const DICTIONARY_ITEM *)rva);
+
     switch(rv->type) {
         case RRDVAR_TYPE_CALCULATED: {
             NETDATA_DOUBLE *n = (NETDATA_DOUBLE *)rv->value;
@@ -190,17 +186,17 @@ NETDATA_DOUBLE rrdvar2number(RRDVAR *rv) {
 
         case RRDVAR_TYPE_TIME_T: {
             time_t *n = (time_t *)rv->value;
-            return *n;
+            return (NETDATA_DOUBLE)*n;
         }
 
         case RRDVAR_TYPE_COLLECTED: {
             collected_number *n = (collected_number *)rv->value;
-            return *n;
+            return (NETDATA_DOUBLE)*n;
         }
 
         case RRDVAR_TYPE_TOTAL: {
             total_number *n = (total_number *)rv->value;
-            return *n;
+            return (NETDATA_DOUBLE)*n;
         }
 
         case RRDVAR_TYPE_INT: {
@@ -214,28 +210,31 @@ NETDATA_DOUBLE rrdvar2number(RRDVAR *rv) {
     }
 }
 
-int health_variable_lookup(const char *variable, uint32_t hash, RRDCALC *rc, NETDATA_DOUBLE *result) {
+int health_variable_lookup(STRING *variable, RRDCALC *rc, NETDATA_DOUBLE *result) {
     RRDSET *st = rc->rrdset;
     if(!st) return 0;
 
     RRDHOST *host = st->rrdhost;
-    RRDVAR *rv;
+    const RRDVAR_ACQUIRED *rva;
 
-    rv = rrdvar_index_find(&st->rrdvar_root_index, variable, hash);
-    if(rv) {
-        *result = rrdvar2number(rv);
+    rva = rrdvar_get_and_acquire(st->rrdvars, variable);
+    if(rva) {
+        *result = rrdvar2number(rva);
+        dictionary_acquired_item_release(st->rrdvars, (const DICTIONARY_ITEM *)rva);
         return 1;
     }
 
-    rv = rrdvar_index_find(&st->rrdfamily->rrdvar_root_index, variable, hash);
-    if(rv) {
-        *result = rrdvar2number(rv);
+    rva = rrdvar_get_and_acquire(rrdfamily_rrdvars_dict(st->rrdfamily), variable);
+    if(rva) {
+        *result = rrdvar2number(rva);
+        dictionary_acquired_item_release(rrdfamily_rrdvars_dict(st->rrdfamily), (const DICTIONARY_ITEM *)rva);
         return 1;
     }
 
-    rv = rrdvar_index_find(&host->rrdvar_root_index, variable, hash);
-    if(rv) {
-        *result = rrdvar2number(rv);
+    rva = rrdvar_get_and_acquire(host->rrdvars, variable);
+    if(rva) {
+        *result = rrdvar2number(rva);
+        dictionary_acquired_item_release(host->rrdvars, (const DICTIONARY_ITEM *)rva);
         return 1;
     }
 
@@ -248,19 +247,19 @@ int health_variable_lookup(const char *variable, uint32_t hash, RRDCALC *rc, NET
 struct variable2json_helper {
     BUFFER *buf;
     size_t counter;
-    RRDVAR_OPTIONS options;
+    RRDVAR_FLAGS options;
 };
 
-static int single_variable2json(void *entry, void *data) {
-    struct variable2json_helper *helper = (struct variable2json_helper *)data;
-    RRDVAR *rv = (RRDVAR *)entry;
-    NETDATA_DOUBLE value = rrdvar2number(rv);
+static int single_variable2json_callback(const DICTIONARY_ITEM *item __maybe_unused, void *entry __maybe_unused, void *helper_data) {
+    struct variable2json_helper *helper = (struct variable2json_helper *)helper_data;
+    const RRDVAR_ACQUIRED *rva = (const RRDVAR_ACQUIRED *)item;
+    NETDATA_DOUBLE value = rrdvar2number(rva);
 
-    if (helper->options == RRDVAR_OPTION_DEFAULT || rv->options & helper->options) {
+    if (helper->options == RRDVAR_FLAG_NONE || rrdvar_flags(rva) & helper->options) {
         if(unlikely(isnan(value) || isinf(value)))
-            buffer_sprintf(helper->buf, "%s\n\t\t\"%s\": null", helper->counter?",":"", rv->name);
+            buffer_sprintf(helper->buf, "%s\n\t\t\"%s\": null", helper->counter?",":"", rrdvar_name(rva));
         else
-            buffer_sprintf(helper->buf, "%s\n\t\t\"%s\": %0.5" NETDATA_DOUBLE_MODIFIER, helper->counter?",":"", rv->name, (NETDATA_DOUBLE)value);
+            buffer_sprintf(helper->buf, "%s\n\t\t\"%s\": %0.5" NETDATA_DOUBLE_MODIFIER, helper->counter?",":"", rrdvar_name(rva), (NETDATA_DOUBLE)value);
 
         helper->counter++;
     }
@@ -272,11 +271,10 @@ void health_api_v1_chart_custom_variables2json(RRDSET *st, BUFFER *buf) {
     struct variable2json_helper helper = {
             .buf = buf,
             .counter = 0,
-            .options = RRDVAR_OPTION_CUSTOM_CHART_VAR
-    };
+            .options = RRDVAR_FLAG_CUSTOM_CHART_VAR};
 
     buffer_sprintf(buf, "{");
-    avl_traverse_lock(&st->rrdvar_root_index, single_variable2json, (void *)&helper);
+    rrdvar_walkthrough_read(st->rrdvars, single_variable2json_callback, &helper);
     buffer_strcat(buf, "\n\t\t\t}");
 }
 
@@ -286,20 +284,34 @@ void health_api_v1_chart_variables2json(RRDSET *st, BUFFER *buf) {
     struct variable2json_helper helper = {
             .buf = buf,
             .counter = 0,
-            .options = RRDVAR_OPTION_DEFAULT
-    };
+            .options = RRDVAR_FLAG_NONE};
 
-    buffer_sprintf(buf, "{\n\t\"chart\": \"%s\",\n\t\"chart_name\": \"%s\",\n\t\"chart_context\": \"%s\",\n\t\"chart_variables\": {", st->id, st->name, st->context);
-    avl_traverse_lock(&st->rrdvar_root_index, single_variable2json, (void *)&helper);
+    buffer_sprintf(buf, "{\n\t\"chart\": \"%s\",\n\t\"chart_name\": \"%s\",\n\t\"chart_context\": \"%s\",\n\t\"chart_variables\": {", rrdset_id(st), rrdset_name(st), rrdset_context(st));
+    rrdvar_walkthrough_read(st->rrdvars, single_variable2json_callback, &helper);
 
-    buffer_sprintf(buf, "\n\t},\n\t\"family\": \"%s\",\n\t\"family_variables\": {", st->family);
+    buffer_sprintf(buf, "\n\t},\n\t\"family\": \"%s\",\n\t\"family_variables\": {", rrdset_family(st));
     helper.counter = 0;
-    avl_traverse_lock(&st->rrdfamily->rrdvar_root_index, single_variable2json, (void *)&helper);
+    rrdvar_walkthrough_read(rrdfamily_rrdvars_dict(st->rrdfamily), single_variable2json_callback, &helper);
 
-    buffer_sprintf(buf, "\n\t},\n\t\"host\": \"%s\",\n\t\"host_variables\": {", host->hostname);
+    buffer_sprintf(buf, "\n\t},\n\t\"host\": \"%s\",\n\t\"host_variables\": {", rrdhost_hostname(host));
     helper.counter = 0;
-    avl_traverse_lock(&host->rrdvar_root_index, single_variable2json, (void *)&helper);
+    rrdvar_walkthrough_read(host->rrdvars, single_variable2json_callback, &helper);
 
     buffer_strcat(buf, "\n\t}\n}\n");
 }
 
+// ----------------------------------------------------------------------------
+// RRDVAR private members examination
+
+const char *rrdvar_name(const RRDVAR_ACQUIRED *rva) {
+    return dictionary_acquired_item_name((const DICTIONARY_ITEM *)rva);
+}
+
+RRDVAR_FLAGS rrdvar_flags(const RRDVAR_ACQUIRED *rva) {
+    RRDVAR *rv = dictionary_acquired_item_value((const DICTIONARY_ITEM *)rva);
+    return rv->flags;
+}
+RRDVAR_TYPE rrdvar_type(const RRDVAR_ACQUIRED *rva) {
+    RRDVAR *rv = dictionary_acquired_item_value((const DICTIONARY_ITEM *)rva);
+    return rv->type;
+}
diff --git a/database/rrdvar.h b/database/rrdvar.h
index 9074edcdb..a511c732d 100644
--- a/database/rrdvar.h
+++ b/database/rrdvar.h
@@ -5,62 +5,67 @@
 
 #include "libnetdata/libnetdata.h"
 
-extern int rrdvar_compare(void *a, void *b);
-
 typedef enum rrdvar_type {
     RRDVAR_TYPE_CALCULATED              = 1,
     RRDVAR_TYPE_TIME_T                  = 2,
     RRDVAR_TYPE_COLLECTED               = 3,
     RRDVAR_TYPE_TOTAL                   = 4,
     RRDVAR_TYPE_INT                     = 5
+
+    // this is 8 bit
+    // to increase it you have to set change the bitfield in
+    // rrdvar, rrdsetvar, rrddimvar
 } RRDVAR_TYPE;
 
 typedef enum rrdvar_options {
-    RRDVAR_OPTION_DEFAULT                    = 0,
-    RRDVAR_OPTION_ALLOCATED                  = (1 << 0), // the value ptr is allocated (not a reference)
-    RRDVAR_OPTION_CUSTOM_HOST_VAR            = (1 << 1), // this is a custom host variable, not associated with a dimension
-    RRDVAR_OPTION_CUSTOM_CHART_VAR           = (1 << 2), // this is a custom chart variable, not associated with a dimension
-    RRDVAR_OPTION_RRDCALC_LOCAL_VAR          = (1 << 3), // this is a an alarm variable, attached to a chart
-    RRDVAR_OPTION_RRDCALC_FAMILY_VAR         = (1 << 4), // this is a an alarm variable, attached to a family
-    RRDVAR_OPTION_RRDCALC_HOST_CHARTID_VAR   = (1 << 5), // this is a an alarm variable, attached to the host, using the chart id
-    RRDVAR_OPTION_RRDCALC_HOST_CHARTNAME_VAR = (1 << 6), // this is a an alarm variable, attached to the host, using the chart name
-} RRDVAR_OPTIONS;
-
-// the variables as stored in the variables indexes
-// there are 3 indexes:
-// 1. at each chart   (RRDSET.rrdvar_root_index)
-// 2. at each context (RRDFAMILY.rrdvar_root_index)
-// 3. at each host    (RRDHOST.rrdvar_root_index)
-struct rrdvar {
-    avl_t avl;
-
-    char *name;
-    uint32_t hash;
-
-    RRDVAR_TYPE type;
-    RRDVAR_OPTIONS options;
-
-    void *value;
-
-    time_t last_updated;
-};
+    RRDVAR_FLAG_NONE                        = 0,
+    RRDVAR_FLAG_ALLOCATED                   = (1 << 0), // the value ptr is allocated (not a reference)
+    RRDVAR_FLAG_CUSTOM_HOST_VAR             = (1 << 1), // this is a custom host variable, not associated with a dimension
+    RRDVAR_FLAG_CUSTOM_CHART_VAR            = (1 << 2), // this is a custom chart variable, not associated with a dimension
+    RRDVAR_FLAG_RRDCALC_LOCAL_VAR           = (1 << 3), // this is a an alarm variable, attached to a chart
+    RRDVAR_FLAG_RRDCALC_FAMILY_VAR          = (1 << 4), // this is a an alarm variable, attached to a family
+    RRDVAR_FLAG_RRDCALC_HOST_CHARTID_VAR    = (1 << 5), // this is a an alarm variable, attached to the host, using the chart id
+    RRDVAR_FLAG_RRDCALC_HOST_CHARTNAME_VAR  = (1 << 6), // this is a an alarm variable, attached to the host, using the chart name
+
+    // this is 24 bit
+    // to increase it you have to set change the bitfield in
+    // rrdvar, rrdsetvar, rrddimvar
+} RRDVAR_FLAGS;
+
+#define RRDVAR_OPTIONS_REMOVED_ON_NEW_OBJECTS \
+    (RRDVAR_FLAG_ALLOCATED)
+
+#define RRDVAR_OPTIONS_REMOVED_WHEN_PROPAGATING_TO_RRDVAR \
+    (RRDVAR_FLAG_ALLOCATED)
 
 #define RRDVAR_MAX_LENGTH 1024
 
-extern int rrdvar_fix_name(char *variable);
+int rrdvar_fix_name(char *variable);
 
 #include "rrd.h"
 
-extern RRDVAR *rrdvar_custom_host_variable_create(RRDHOST *host, const char *name);
-extern void rrdvar_custom_host_variable_set(RRDHOST *host, RRDVAR *rv, NETDATA_DOUBLE value);
-extern int foreach_host_variable_callback(RRDHOST *host, int (*callback)(RRDVAR *rv, void *data), void *data);
-extern void rrdvar_free_remaining_variables(RRDHOST *host, avl_tree_lock *tree_lock);
+STRING *rrdvar_name_to_string(const char *name);
+
+const RRDVAR_ACQUIRED *rrdvar_custom_host_variable_add_and_acquire(RRDHOST *host, const char *name);
+void rrdvar_custom_host_variable_set(RRDHOST *host, const RRDVAR_ACQUIRED *rva, NETDATA_DOUBLE value);
+
+int rrdvar_walkthrough_read(DICTIONARY *dict, int (*callback)(const DICTIONARY_ITEM *item, void *rrdvar, void *data), void *data);
+
+#define rrdvar_custom_host_variable_release(host, rva) rrdvar_release((host)->rrdvars, rva)
+void rrdvar_release(DICTIONARY *dict, const RRDVAR_ACQUIRED *rva);
+
+NETDATA_DOUBLE rrdvar2number(const RRDVAR_ACQUIRED *rva);
+
+const RRDVAR_ACQUIRED *rrdvar_add_and_acquire(const char *scope, DICTIONARY *dict, STRING *name, RRDVAR_TYPE type, RRDVAR_FLAGS options, void *value);
+void rrdvar_release_and_del(DICTIONARY *dict, const RRDVAR_ACQUIRED *rva);
 
-extern int  rrdvar_callback_for_all_host_variables(RRDHOST *host, int (*callback)(void *rrdvar, void *data), void *data);
+DICTIONARY *rrdvariables_create(void);
+void rrdvariables_destroy(DICTIONARY *dict);
 
-extern NETDATA_DOUBLE rrdvar2number(RRDVAR *rv);
+void rrdvar_delete_all(DICTIONARY *dict);
 
-extern RRDVAR *rrdvar_create_and_index(const char *scope, avl_tree_lock *tree, const char *name, RRDVAR_TYPE type, RRDVAR_OPTIONS options, void *value);
-extern void rrdvar_free(RRDHOST *host, avl_tree_lock *tree, RRDVAR *rv);
+const char *rrdvar_name(const RRDVAR_ACQUIRED *rva);
+RRDVAR_FLAGS rrdvar_flags(const RRDVAR_ACQUIRED *rva);
+RRDVAR_TYPE rrdvar_type(const RRDVAR_ACQUIRED *rva);
 
 #endif //NETDATA_RRDVAR_H
diff --git a/database/sqlite/sqlite_aclk.c b/database/sqlite/sqlite_aclk.c
index 43b341097..7e3a9b2eb 100644
--- a/database/sqlite/sqlite_aclk.c
+++ b/database/sqlite/sqlite_aclk.c
@@ -3,59 +3,20 @@
 #include "sqlite_functions.h"
 #include "sqlite_aclk.h"
 
-#include "sqlite_aclk_chart.h"
 #include "sqlite_aclk_node.h"
 
-#ifdef ENABLE_ACLK
-#include "../../aclk/aclk.h"
-#endif
-
 void sanity_check(void) {
     // make sure the compiler will stop on misconfigurations
     BUILD_BUG_ON(WORKER_UTILIZATION_MAX_JOB_TYPES < ACLK_MAX_ENUMERATIONS_DEFINED);
 }
 
 const char *aclk_sync_config[] = {
-    "CREATE TABLE IF NOT EXISTS dimension_delete (dimension_id blob, dimension_name text, chart_type_id text, "
-    "dim_id blob, chart_id blob, host_id blob, date_created);",
-
-    "CREATE INDEX IF NOT EXISTS ind_h1 ON dimension_delete (host_id);",
-
-    "CREATE TRIGGER IF NOT EXISTS tr_dim_del AFTER DELETE ON dimension BEGIN INSERT INTO dimension_delete "
-    "(dimension_id, dimension_name, chart_type_id, dim_id, chart_id, host_id, date_created)"
-    " select old.id, old.name, c.type||\".\"||c.id, old.dim_id, old.chart_id, c.host_id, unixepoch() FROM"
-    " chart c WHERE c.chart_id = old.chart_id; END;",
-
-    "DELETE FROM dimension_delete WHERE host_id NOT IN"
-    " (SELECT host_id FROM host) OR unixepoch() - date_created > 604800;",
 
     NULL,
 };
 
 uv_mutex_t aclk_async_lock;
 struct aclk_database_worker_config  *aclk_thread_head = NULL;
-int retention_running = 0;
-
-#ifdef ENABLE_ACLK
-static void stop_retention_run()
-{
-    uv_mutex_lock(&aclk_async_lock);
-    retention_running = 0;
-    uv_mutex_unlock(&aclk_async_lock);
-}
-
-static int request_retention_run()
-{
-    int rc = 0;
-    uv_mutex_lock(&aclk_async_lock);
-    if (unlikely(retention_running))
-        rc = 1;
-    else
-        retention_running = 1;
-    uv_mutex_unlock(&aclk_async_lock);
-    return rc;
-}
-#endif
 
 int claimed()
 {
@@ -197,25 +158,6 @@ struct aclk_database_cmd aclk_database_deq_cmd(struct aclk_database_worker_confi
     return ret;
 }
 
-int aclk_worker_enq_cmd(char *node_id, struct aclk_database_cmd *cmd)
-{
-    if (unlikely(!node_id || !cmd))
-        return 0;
-
-    uv_mutex_lock(&aclk_async_lock);
-    struct aclk_database_worker_config *wc = aclk_thread_head;
-
-    while (wc) {
-        if (!strcmp(wc->node_id, node_id))
-            break;
-        wc = wc->next;
-    }
-    uv_mutex_unlock(&aclk_async_lock);
-    if (wc)
-        aclk_database_enq_cmd(wc, cmd);
-    return (wc == NULL);
-}
-
 struct aclk_database_worker_config *find_inactive_wc_by_node_id(char *node_id)
 {
     if (unlikely(!node_id))
@@ -237,15 +179,14 @@ struct aclk_database_worker_config *find_inactive_wc_by_node_id(char *node_id)
 void aclk_sync_exit_all()
 {
     rrd_rdlock();
-    RRDHOST *host = localhost;
-    while(host) {
+    RRDHOST *host;
+    rrdhost_foreach_read(host) {
         struct aclk_database_worker_config *wc = host->dbsync_worker;
         if (wc) {
             wc->is_shutting_down = 1;
             (void) aclk_database_deq_cmd(wc);
             uv_cond_signal(&wc->cmd_cond);
         }
-        host = host->next;
     }
     rrd_unlock();
 
@@ -304,23 +245,26 @@ static int create_host_callback(void *data, int argc, char **argv, char **column
         , (const char *) (argv[IDX_PROGRAM_VERSION] ? argv[IDX_PROGRAM_VERSION] : "unknown")
         , argv[3] ? str2i(argv[IDX_UPDATE_EVERY]) : 1
         , argv[13] ? str2i(argv[IDX_ENTRIES]) : 0
-        , RRD_MEMORY_MODE_DBENGINE
+        , default_rrd_memory_mode
         , 0 // health
         , 0 // rrdpush enabled
         , NULL  //destination
         , NULL  // api key
         , NULL  // send charts matching
+        , false // rrdpush_enable_replication
+        , 0     // rrdpush_seconds_to_replicate
+        , 0     // rrdpush_replication_step
         , system_info
         , 1
     );
     if (likely(host))
-        host->host_labels = sql_load_host_labels((uuid_t *)argv[IDX_HOST_ID]);
+        host->rrdlabels = sql_load_host_labels((uuid_t *)argv[IDX_HOST_ID]);
 
 #ifdef NETDATA_INTERNAL_CHECKS
     char node_str[UUID_STR_LEN] = "<none>";
     if (likely(host->node_id))
         uuid_unparse_lower(*host->node_id, node_str);
-    internal_error(true, "Adding archived host \"%s\" with GUID \"%s\" node id = \"%s\"", host->hostname, host->machine_guid, node_str);
+    internal_error(true, "Adding archived host \"%s\" with GUID \"%s\" node id = \"%s\"", rrdhost_hostname(host), host->machine_guid, node_str);
 #endif
     return 0;
 }
@@ -335,7 +279,7 @@ int aclk_start_sync_thread(void *data, int argc, char **argv, char **column)
 
     uuid_unparse_lower(*((uuid_t *) argv[0]), uuid_str);
 
-    RRDHOST *host = rrdhost_find_by_guid(uuid_str, 0);
+    RRDHOST *host = rrdhost_find_by_guid(uuid_str);
     if (host == localhost)
         return 0;
 
@@ -361,7 +305,7 @@ void sql_aclk_sync_init(void)
 
     for (int i = 0; aclk_sync_config[i]; i++) {
         debug(D_ACLK_SYNC, "Executing %s", aclk_sync_config[i]);
-        rc = sqlite3_exec(db_meta, aclk_sync_config[i], 0, 0, &err_msg);
+        rc = sqlite3_exec_monitored(db_meta, aclk_sync_config[i], 0, 0, &err_msg);
         if (rc != SQLITE_OK) {
             error_report("SQLite error aclk sync initialization setup, rc = %d (%s)", rc, err_msg);
             error_report("SQLite failed statement %s", aclk_sync_config[i]);
@@ -372,18 +316,16 @@ void sql_aclk_sync_init(void)
     info("SQLite aclk sync initialization completed");
     fatal_assert(0 == uv_mutex_init(&aclk_async_lock));
 
-    if (likely(rrdcontext_enabled == CONFIG_BOOLEAN_YES)) {
-        rc = sqlite3_exec(db_meta, "SELECT host_id, hostname, registry_hostname, update_every, os, "
-           "timezone, tags, hops, memory_mode, abbrev_timezone, utc_offset, program_name, "
-           "program_version, entries, health_enabled FROM host WHERE hops >0;",
-              create_host_callback, NULL, &err_msg);
-        if (rc != SQLITE_OK) {
-            error_report("SQLite error when loading archived hosts, rc = %d (%s)", rc, err_msg);
-            sqlite3_free(err_msg);
-        }
+    rc = sqlite3_exec_monitored(db_meta, "SELECT host_id, hostname, registry_hostname, update_every, os, "
+       "timezone, tags, hops, memory_mode, abbrev_timezone, utc_offset, program_name, "
+       "program_version, entries, health_enabled FROM host WHERE hops >0;",
+          create_host_callback, NULL, &err_msg);
+    if (rc != SQLITE_OK) {
+        error_report("SQLite error when loading archived hosts, rc = %d (%s)", rc, err_msg);
+        sqlite3_free(err_msg);
     }
 
-    rc = sqlite3_exec(db_meta, "SELECT ni.host_id, ni.node_id FROM host h, node_instance ni WHERE "
+    rc = sqlite3_exec_monitored(db_meta, "SELECT ni.host_id, ni.node_id FROM host h, node_instance ni WHERE "
         "h.host_id = ni.host_id AND ni.node_id IS NOT NULL;", aclk_start_sync_thread, NULL, &err_msg);
     if (rc != SQLITE_OK) {
         error_report("SQLite error when starting ACLK sync threads, rc = %d (%s)", rc, err_msg);
@@ -423,30 +365,6 @@ static void timer_cb(uv_timer_t* handle)
     }
 
     if (aclk_connected) {
-        if (wc->rotation_after && wc->rotation_after < now) {
-            cmd.opcode = ACLK_DATABASE_UPD_RETENTION;
-            if (!aclk_database_enq_cmd_noblock(wc, &cmd))
-                wc->rotation_after += ACLK_DATABASE_ROTATION_INTERVAL;
-        }
-
-        if (wc->chart_updates && !wc->chart_pending && wc->chart_payload_count) {
-            cmd.opcode = ACLK_DATABASE_PUSH_CHART;
-            cmd.count = ACLK_MAX_CHART_BATCH;
-            cmd.param1 = ACLK_MAX_CHART_BATCH_COUNT;
-            if (!aclk_database_enq_cmd_noblock(wc, &cmd)) {
-                if (wc->retry_count)
-                    info("Queued chart/dimension payload command %s, retry count = %u", wc->host_guid, wc->retry_count);
-                wc->chart_pending = 1;
-                wc->retry_count = 0;
-            } else {
-                wc->retry_count++;
-                if (wc->retry_count % 100 == 0)
-                    error_report("Failed to queue chart/dimension payload command %s, retry count = %u",
-                        wc->host_guid,
-                        wc->retry_count);
-            }
-        }
-
         if (wc->alert_updates && !wc->pause_alert_updates) {
             cmd.opcode = ACLK_DATABASE_PUSH_ALERT;
             cmd.count = ACLK_MAX_ALERT_UPDATES;
@@ -456,52 +374,12 @@ static void timer_cb(uv_timer_t* handle)
 #endif
 }
 
-
-#ifdef ENABLE_ACLK
-void after_send_retention(uv_work_t *req, int status)
-{
-    struct aclk_database_worker_config *wc = req->data;
-    (void)status;
-    stop_retention_run();
-    wc->retention_running = 0;
-
-    struct aclk_database_cmd cmd;
-    memset(&cmd, 0, sizeof(cmd));
-    cmd.opcode = ACLK_DATABASE_DIM_DELETION;
-    if (aclk_database_enq_cmd_noblock(wc, &cmd))
-        info("Failed to queue a dimension deletion message");
-
-    cmd.opcode = ACLK_DATABASE_NODE_INFO;
-    if (aclk_database_enq_cmd_noblock(wc, &cmd))
-        info("Failed to queue a node update info message");
-}
-
-
-static void send_retention(uv_work_t *req)
-{
-    struct aclk_database_worker_config *wc = req->data;
-
-    if (unlikely(wc->is_shutting_down))
-        return;
-
-    aclk_update_retention(wc);
-}
-#endif
-
 #define MAX_CMD_BATCH_SIZE (256)
 
 void aclk_database_worker(void *arg)
 {
     worker_register("ACLKSYNC");
     worker_register_job_name(ACLK_DATABASE_NOOP,                 "noop");
-    worker_register_job_name(ACLK_DATABASE_ADD_CHART,            "chart add");
-    worker_register_job_name(ACLK_DATABASE_ADD_DIMENSION,        "dimension add");
-    worker_register_job_name(ACLK_DATABASE_PUSH_CHART,           "chart push");
-    worker_register_job_name(ACLK_DATABASE_PUSH_CHART_CONFIG,    "chart conf push");
-    worker_register_job_name(ACLK_DATABASE_RESET_CHART,          "chart reset");
-    worker_register_job_name(ACLK_DATABASE_CHART_ACK,            "chart ack");
-    worker_register_job_name(ACLK_DATABASE_UPD_RETENTION,        "retention check");
-    worker_register_job_name(ACLK_DATABASE_DIM_DELETION,         "dimension delete");
     worker_register_job_name(ACLK_DATABASE_ORPHAN_HOST,          "node orphan");
     worker_register_job_name(ACLK_DATABASE_ALARM_HEALTH_LOG,     "alert log");
     worker_register_job_name(ACLK_DATABASE_CLEANUP,              "cleanup");
@@ -526,7 +404,7 @@ void aclk_database_worker(void *arg)
 
     char threadname[NETDATA_THREAD_NAME_MAX+1];
     if (wc->host)
-        snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "AS_%s", wc->host->hostname);
+        snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "AS_%s", rrdhost_hostname(wc->host));
     else {
         snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "AS_%s", wc->uuid_str);
         threadname[11] = '\0';
@@ -556,23 +434,13 @@ void aclk_database_worker(void *arg)
     timer_req.data = wc;
     fatal_assert(0 == uv_timer_start(&timer_req, timer_cb, TIMER_PERIOD_MS, TIMER_PERIOD_MS));
 
-//    wc->retry_count = 0;
     wc->node_info_send = 1;
-//    aclk_add_worker_thread(wc);
-    info("Starting ACLK sync thread for host %s -- scratch area %lu bytes", wc->host_guid, sizeof(*wc));
+    info("Starting ACLK sync thread for host %s -- scratch area %lu bytes", wc->host_guid, (unsigned long int) sizeof(*wc));
 
     memset(&cmd, 0, sizeof(cmd));
-#ifdef ENABLE_ACLK
-    uv_work_t retention_work;
-    sql_get_last_chart_sequence(wc);
-    wc->chart_payload_count = sql_get_pending_count(wc);
-    if (!wc->chart_payload_count)
-        info("%s: No pending charts and dimensions detected during startup", wc->host_guid);
-#endif
 
     wc->startup_time = now_realtime_sec();
     wc->cleanup_after = wc->startup_time + ACLK_DATABASE_CLEANUP_FIRST;
-    wc->rotation_after = wc->startup_time + ACLK_DATABASE_ROTATION_DELAY;
 
     debug(D_ACLK_SYNC,"Node %s reports pending message count = %u", wc->node_id, wc->chart_payload_count);
 
@@ -604,6 +472,13 @@ void aclk_database_worker(void *arg)
 // MAINTENANCE
                 case ACLK_DATABASE_CLEANUP:
                     debug(D_ACLK_SYNC, "Database cleanup for %s", wc->host_guid);
+
+                    if (wc->startup_time + ACLK_DATABASE_CLEANUP_FIRST + 2 < now_realtime_sec() && claimed() && aclk_connected) {
+                        cmd.opcode = ACLK_DATABASE_NODE_INFO;
+                        cmd.completion = NULL;
+                        (void) aclk_database_enq_cmd_noblock(wc, &cmd);
+                    }
+
                     sql_maint_aclk_sync_database(wc, cmd);
                     if (wc->host == localhost)
                         sql_check_aclk_table_list(wc);
@@ -614,33 +489,6 @@ void aclk_database_worker(void *arg)
                     sql_delete_aclk_table_list(wc, cmd);
                     break;
 
-// CHART / DIMENSION OPERATIONS
-#ifdef ENABLE_ACLK
-                case ACLK_DATABASE_ADD_CHART:
-                    debug(D_ACLK_SYNC, "Adding chart event for %s", wc->host_guid);
-                    aclk_add_chart_event(wc, cmd);
-                    break;
-                case ACLK_DATABASE_ADD_DIMENSION:
-                    debug(D_ACLK_SYNC, "Adding dimension event for %s", wc->host_guid);
-                    aclk_add_dimension_event(wc, cmd);
-                    break;
-                case ACLK_DATABASE_PUSH_CHART:
-                    debug(D_ACLK_SYNC, "Pushing chart info to the cloud for node %s", wc->host_guid);
-                    aclk_send_chart_event(wc, cmd);
-                    break;
-                case ACLK_DATABASE_PUSH_CHART_CONFIG:
-                    debug(D_ACLK_SYNC, "Pushing chart config info to the cloud for node %s", wc->host_guid);
-                    aclk_send_chart_config(wc, cmd);
-                    break;
-                case ACLK_DATABASE_CHART_ACK:
-                    debug(D_ACLK_SYNC, "ACK chart SEQ for %s to %"PRIu64, wc->uuid_str, (uint64_t) cmd.param1);
-                    aclk_receive_chart_ack(wc, cmd);
-                    break;
-                case ACLK_DATABASE_RESET_CHART:
-                    debug(D_ACLK_SYNC, "RESET chart SEQ for %s to %"PRIu64, wc->uuid_str, (uint64_t) cmd.param1);
-                    aclk_receive_chart_reset(wc, cmd);
-                    break;
-#endif
 // ALERTS
                 case ACLK_DATABASE_PUSH_ALERT_CONFIG:
                     debug(D_ACLK_SYNC,"Pushing chart config info to the cloud for %s", wc->host_guid);
@@ -673,27 +521,6 @@ void aclk_database_worker(void *arg)
                     sql_build_node_collectors(wc);
                     break;
 #ifdef ENABLE_ACLK
-                case ACLK_DATABASE_DIM_DELETION:
-                    debug(D_ACLK_SYNC,"Sending dimension deletion information %s", wc->uuid_str);
-                    aclk_process_dimension_deletion(wc, cmd);
-                    break;
-                case ACLK_DATABASE_UPD_RETENTION:
-                    if (unlikely(wc->retention_running))
-                        break;
-
-                    if (unlikely(request_retention_run())) {
-                        wc->rotation_after = now_realtime_sec() + ACLK_DATABASE_RETENTION_RETRY;
-                        break;
-                    }
-
-                    debug(D_ACLK_SYNC,"Sending retention info for %s", wc->uuid_str);
-                    retention_work.data = wc;
-                    wc->retention_running = 1;
-                    if (unlikely(uv_queue_work(loop, &retention_work, send_retention, after_send_retention))) {
-                        wc->retention_running = 0;
-                        stop_retention_run();
-                    }
-                    break;
 
 // NODE_INSTANCE DETECTION
                 case ACLK_DATABASE_ORPHAN_HOST:
@@ -705,14 +532,14 @@ void aclk_database_worker(void *arg)
                 case ACLK_DATABASE_TIMER:
                     if (unlikely(localhost && !wc->host && !wc->is_orphan)) {
                         if (claimed()) {
-                            wc->host = rrdhost_find_by_guid(wc->host_guid, 0);
+                            wc->host = rrdhost_find_by_guid(wc->host_guid);
                             if (wc->host) {
-                                info("HOST %s (%s) detected as active", wc->host->hostname, wc->host_guid);
-                                snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "AS_%s", wc->host->hostname);
+                                info("HOST %s (%s) detected as active", rrdhost_hostname(wc->host), wc->host_guid);
+                                snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "AS_%s", rrdhost_hostname(wc->host));
                                 uv_thread_set_name_np(wc->thread, threadname);
                                 wc->host->dbsync_worker = wc;
                                 if (unlikely(!wc->hostname))
-                                    wc->hostname = strdupz(wc->host->hostname);
+                                    wc->hostname = strdupz(rrdhost_hostname(wc->host));
                                 aclk_del_worker_thread(wc);
                                 wc->node_info_send = 1;
                             }
@@ -803,30 +630,6 @@ void sql_create_aclk_table(RRDHOST *host, uuid_t *host_uuid, uuid_t *node_id)
 
     BUFFER *sql = buffer_create(ACLK_SYNC_QUERY_SIZE);
 
-    buffer_sprintf(sql, TABLE_ACLK_CHART, uuid_str);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql, TABLE_ACLK_CHART_PAYLOAD, uuid_str);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql, TABLE_ACLK_CHART_LATEST, uuid_str);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql, INDEX_ACLK_CHART, uuid_str, uuid_str);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql, INDEX_ACLK_CHART_LATEST, uuid_str, uuid_str);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql, TRIGGER_ACLK_CHART_PAYLOAD, uuid_str, uuid_str, uuid_str);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
     buffer_sprintf(sql, TABLE_ACLK_ALERT, uuid_str);
     db_execute(buffer_tostring(sql));
     buffer_flush(sql);
@@ -844,16 +647,14 @@ void sql_create_aclk_table(RRDHOST *host, uuid_t *host_uuid, uuid_t *node_id)
         uuid_unparse_lower(*node_id, wc->node_id);
     if (likely(host)) {
         host->dbsync_worker = (void *)wc;
-        wc->hostname = strdupz(host->hostname);
+        wc->hostname = strdupz(rrdhost_hostname(host));
     }
     else
         wc->hostname = get_hostname_by_node_id(wc->node_id);
     wc->host = host;
     strcpy(wc->uuid_str, uuid_str);
     strcpy(wc->host_guid, host_guid);
-    wc->chart_updates = 0;
     wc->alert_updates = 0;
-    wc->retry_count = 0;
     aclk_database_init_cmd_queue(wc);
     aclk_add_worker_thread(wc);
     fatal_assert(0 == uv_thread_create(&(wc->thread), aclk_database_worker, wc));
@@ -873,31 +674,9 @@ void sql_maint_aclk_sync_database(struct aclk_database_worker_config *wc, struct
 
     BUFFER *sql = buffer_create(ACLK_SYNC_QUERY_SIZE);
 
-    buffer_sprintf(sql,"DELETE FROM aclk_chart_%s WHERE date_submitted IS NOT NULL AND "
-        "CAST(date_updated AS INT) < unixepoch()-%d;", wc->uuid_str, ACLK_DELETE_ACK_INTERNAL);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql,"DELETE FROM aclk_chart_payload_%s WHERE unique_id NOT IN "
-        "(SELECT unique_id FROM aclk_chart_%s) AND unique_id NOT IN (SELECT unique_id FROM aclk_chart_latest_%s);",
-          wc->uuid_str,  wc->uuid_str, wc->uuid_str);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
     buffer_sprintf(sql,"DELETE FROM aclk_alert_%s WHERE date_submitted IS NOT NULL AND "
         "CAST(date_cloud_ack AS INT) < unixepoch()-%d;", wc->uuid_str, ACLK_DELETE_ACK_ALERTS_INTERNAL);
     db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql,"UPDATE aclk_chart_%s SET status = NULL, date_submitted=unixepoch() WHERE "
-            "date_submitted IS NULL AND CAST(date_created AS INT) < unixepoch()-%d;", wc->uuid_str, ACLK_AUTO_MARK_SUBMIT_INTERVAL);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql,"UPDATE aclk_chart_%s SET date_updated = unixepoch() WHERE date_updated IS NULL"
-                " AND date_submitted IS NOT NULL AND CAST(date_submitted AS INT) < unixepoch()-%d;",
-                wc->uuid_str, ACLK_AUTO_MARK_UPDATED_INTERVAL);
-    db_execute(buffer_tostring(sql));
 
     buffer_free(sql);
     return;
@@ -927,7 +706,7 @@ static int is_host_available(uuid_t *host_id)
         error_report("Failed to bind host_id parameter to select node instance information");
         goto failed;
     }
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
 
     failed:
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
@@ -980,7 +759,7 @@ void sql_delete_aclk_table_list(struct aclk_database_worker_config *wc, struct a
     }
     buffer_flush(sql);
 
-    while (sqlite3_step(res) == SQLITE_ROW)
+    while (sqlite3_step_monitored(res) == SQLITE_ROW)
         buffer_strcat(sql, (char *) sqlite3_column_text(res, 0));
 
     rc = sqlite3_finalize(res);
@@ -1016,42 +795,10 @@ void sql_check_aclk_table_list(struct aclk_database_worker_config *wc)
 {
     char *err_msg = NULL;
     debug(D_ACLK_SYNC,"Cleaning tables for nodes that do not exist");
-    int rc = sqlite3_exec(db_meta, SQL_SELECT_ACLK_ACTIVE_LIST, sql_check_aclk_table, (void *) wc, &err_msg);
+    int rc = sqlite3_exec_monitored(db_meta, SQL_SELECT_ACLK_ACTIVE_LIST, sql_check_aclk_table, (void *) wc, &err_msg);
     if (rc != SQLITE_OK) {
         error_report("Query failed when trying to check for obsolete ACLK sync tables, %s", err_msg);
         sqlite3_free(err_msg);
     }
-    db_execute("DELETE FROM dimension_delete WHERE host_id NOT IN (SELECT host_id FROM host) "
-               " OR unixepoch() - date_created > 604800;");
-    return;
-}
-
-void aclk_data_rotated(void)
-{
-#ifdef ENABLE_ACLK
-
-    if (!aclk_connected)
-        return;
-
-    time_t next_rotation_time = now_realtime_sec()+ACLK_DATABASE_ROTATION_DELAY;
-    rrd_rdlock();
-    RRDHOST *this_host = localhost;
-    while (this_host) {
-        struct aclk_database_worker_config *wc = this_host->dbsync_worker;
-        if (wc)
-            wc->rotation_after = next_rotation_time;
-        this_host = this_host->next;
-    }
-    rrd_unlock();
-
-    struct aclk_database_worker_config *tmp = aclk_thread_head;
-
-    uv_mutex_lock(&aclk_async_lock);
-    while (tmp) {
-        tmp->rotation_after = next_rotation_time;
-        tmp = tmp->next;
-    }
-    uv_mutex_unlock(&aclk_async_lock);
-#endif
     return;
 }
diff --git a/database/sqlite/sqlite_aclk.h b/database/sqlite/sqlite_aclk.h
index b73f422e1..06d5d0270 100644
--- a/database/sqlite/sqlite_aclk.h
+++ b/database/sqlite/sqlite_aclk.h
@@ -5,8 +5,6 @@
 
 #include "sqlite3.h"
 
-// TODO: To be added
-#include "../../aclk/schema-wrappers/chart_stream.h"
 
 #ifndef ACLK_MAX_CHART_BATCH
 #define ACLK_MAX_CHART_BATCH    (200)
@@ -15,15 +13,9 @@
 #define ACLK_MAX_CHART_BATCH_COUNT (10)
 #endif
 #define ACLK_MAX_ALERT_UPDATES  (5)
-#define ACLK_DATABASE_CLEANUP_FIRST  (60)
-#define ACLK_DATABASE_ROTATION_DELAY  (180)
-#define ACLK_DATABASE_RETENTION_RETRY (60)
+#define ACLK_DATABASE_CLEANUP_FIRST  (1200)
 #define ACLK_DATABASE_CLEANUP_INTERVAL (3600)
-#define ACLK_DATABASE_ROTATION_INTERVAL (3600)
-#define ACLK_DELETE_ACK_INTERNAL (600)
 #define ACLK_DELETE_ACK_ALERTS_INTERNAL (86400)
-#define ACLK_AUTO_MARK_SUBMIT_INTERVAL (3600)
-#define ACLK_AUTO_MARK_UPDATED_INTERVAL (1800)
 #define ACLK_SYNC_QUERY_SIZE 512
 
 struct aclk_completion {
@@ -74,57 +66,14 @@ static inline void uuid_unparse_lower_fix(uuid_t *uuid, char *out)
     out[23] = '_';
 }
 
-static inline char *get_str_from_uuid(uuid_t *uuid)
-{
-    char uuid_str[GUID_LEN + 1];
-    if (unlikely(!uuid)) {
-        uuid_t zero_uuid;
-        uuid_clear(zero_uuid);
-        uuid_unparse_lower(zero_uuid, uuid_str);
-    }
-    else
-        uuid_unparse_lower(*uuid, uuid_str);
-    return strdupz(uuid_str);
-}
-
-#define TABLE_ACLK_CHART "CREATE TABLE IF NOT EXISTS aclk_chart_%s (sequence_id INTEGER PRIMARY KEY, " \
-        "date_created, date_updated, date_submitted, status, uuid, type, unique_id, " \
-        "update_count default 1, unique(uuid, status));"
-
-#define TABLE_ACLK_CHART_PAYLOAD "CREATE TABLE IF NOT EXISTS aclk_chart_payload_%s (unique_id BLOB PRIMARY KEY, " \
-        "uuid, claim_id, type, date_created, payload);"
-
-#define TABLE_ACLK_CHART_LATEST "CREATE TABLE IF NOT EXISTS aclk_chart_latest_%s (uuid BLOB PRIMARY KEY, " \
-        "unique_id, date_submitted);"
-
-#define TRIGGER_ACLK_CHART_PAYLOAD "CREATE TRIGGER IF NOT EXISTS aclk_tr_chart_payload_%s " \
-        "after insert on aclk_chart_payload_%s " \
-        "begin insert into aclk_chart_%s (uuid, unique_id, type, status, date_created) values " \
-        " (new.uuid, new.unique_id, new.type, 'pending', unixepoch()) on conflict(uuid, status) " \
-        " do update set unique_id = new.unique_id, update_count = update_count + 1; " \
-        "end;"
-
 #define TABLE_ACLK_ALERT "CREATE TABLE IF NOT EXISTS aclk_alert_%s (sequence_id INTEGER PRIMARY KEY, " \
-        "alert_unique_id, date_created, date_submitted, date_cloud_ack, " \
+        "alert_unique_id, date_created, date_submitted, date_cloud_ack, filtered_alert_unique_id NOT NULL, " \
         "unique(alert_unique_id));"
 
-#define INDEX_ACLK_CHART "CREATE INDEX IF NOT EXISTS aclk_chart_index_%s ON aclk_chart_%s (unique_id);"
-
-#define INDEX_ACLK_CHART_LATEST  "CREATE INDEX IF NOT EXISTS aclk_chart_latest_index_%s ON aclk_chart_latest_%s (unique_id);"
-
 #define INDEX_ACLK_ALERT "CREATE INDEX IF NOT EXISTS aclk_alert_index_%s ON aclk_alert_%s (alert_unique_id);"
-
 enum aclk_database_opcode {
     ACLK_DATABASE_NOOP = 0,
 
-    ACLK_DATABASE_ADD_CHART,
-    ACLK_DATABASE_ADD_DIMENSION,
-    ACLK_DATABASE_PUSH_CHART,
-    ACLK_DATABASE_PUSH_CHART_CONFIG,
-    ACLK_DATABASE_RESET_CHART,
-    ACLK_DATABASE_CHART_ACK,
-    ACLK_DATABASE_UPD_RETENTION,
-    ACLK_DATABASE_DIM_DELETION,
     ACLK_DATABASE_ORPHAN_HOST,
     ACLK_DATABASE_ALARM_HEALTH_LOG,
     ACLK_DATABASE_CLEANUP,
@@ -142,20 +91,11 @@ enum aclk_database_opcode {
     ACLK_MAX_ENUMERATIONS_DEFINED
 };
 
-struct aclk_chart_payload_t {
-    long sequence_id;
-    long last_sequence_id;
-    char *payload;
-    struct aclk_chart_payload_t *next;
-};
-
-
 struct aclk_database_cmd {
     enum aclk_database_opcode opcode;
     void *data;
     void *data_param;
     int count;
-    uint64_t param1;
     struct aclk_completion *completion;
 };
 
@@ -172,12 +112,8 @@ struct aclk_database_worker_config {
     char node_id[GUID_LEN + 1];
     char host_guid[GUID_LEN + 1];
     char *hostname;                 // hostname to avoid constant lookups
-    uint64_t chart_sequence_id;     // last chart_sequence_id
-    time_t chart_timestamp;         // last chart timestamp
     time_t cleanup_after;           // Start a cleanup after this timestamp
     time_t startup_time;           // When the sync thread started
-    time_t rotation_after;
-    uint64_t batch_id;    // batch id to use
     uint64_t alerts_batch_id; // batch id for alerts to use
     uint64_t alerts_start_seq_id; // cloud has asked to start streaming from
     uint64_t alert_sequence_id; // last alert sequence_id
@@ -193,15 +129,9 @@ struct aclk_database_worker_config {
     uv_cond_t cmd_cond;
     volatile unsigned queue_size;
     struct aclk_database_cmdqueue cmd_queue;
-    uint32_t retry_count;
-    int chart_updates;
     int alert_updates;
-    time_t batch_created;
     int node_info_send;
     time_t node_collectors_send;
-    int chart_pending;
-    int chart_reset_count;
-    int retention_running;
     volatile unsigned is_shutting_down;
     volatile unsigned is_orphan;
     struct aclk_database_worker_config  *next;
@@ -216,23 +146,25 @@ static inline RRDHOST *find_host_by_node_id(char *node_id)
     if (uuid_parse(node_id, node_uuid))
         return NULL;
 
-    RRDHOST *host = localhost;
-    while(host) {
-        if (host->node_id && !(uuid_compare(*host->node_id, node_uuid)))
-            return host;
-        host = host->next;
+    rrd_rdlock();
+    RRDHOST *host, *ret = NULL;
+    rrdhost_foreach_read(host) {
+        if (host->node_id && !(uuid_compare(*host->node_id, node_uuid))) {
+            ret = host;
+            break;
+        }
     }
-    return NULL;
+    rrd_unlock();
+
+    return ret;
 }
 
 
 extern sqlite3 *db_meta;
 
-extern int aclk_database_enq_cmd_noblock(struct aclk_database_worker_config *wc, struct aclk_database_cmd *cmd);
-extern void aclk_database_enq_cmd(struct aclk_database_worker_config *wc, struct aclk_database_cmd *cmd);
-extern void sql_create_aclk_table(RRDHOST *host, uuid_t *host_uuid, uuid_t *node_id);
-int aclk_worker_enq_cmd(char *node_id, struct aclk_database_cmd *cmd);
-void aclk_data_rotated(void);
+int aclk_database_enq_cmd_noblock(struct aclk_database_worker_config *wc, struct aclk_database_cmd *cmd);
+void aclk_database_enq_cmd(struct aclk_database_worker_config *wc, struct aclk_database_cmd *cmd);
+void sql_create_aclk_table(RRDHOST *host, uuid_t *host_uuid, uuid_t *node_id);
 void sql_aclk_sync_init(void);
 void sql_check_aclk_table_list(struct aclk_database_worker_config *wc);
 void sql_delete_aclk_table_list(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
diff --git a/database/sqlite/sqlite_aclk_alert.c b/database/sqlite/sqlite_aclk_alert.c
index ea1cc9fea..47663a8d1 100644
--- a/database/sqlite/sqlite_aclk_alert.c
+++ b/database/sqlite/sqlite_aclk_alert.c
@@ -24,7 +24,7 @@ time_t removed_when(uint32_t alarm_id, uint32_t before_unique_id, uint32_t after
         return 0;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
     if (likely(rc == SQLITE_ROW)) {
         when = (time_t) sqlite3_column_int64(res, 0);
     }
@@ -36,7 +36,14 @@ time_t removed_when(uint32_t alarm_id, uint32_t before_unique_id, uint32_t after
     return when;
 }
 
-#define MAX_REMOVED_PERIOD 900
+void update_filtered(ALARM_ENTRY *ae, uint32_t unique_id, char *uuid_str) {
+    char sql[ACLK_SYNC_QUERY_SIZE];
+    snprintfz(sql, ACLK_SYNC_QUERY_SIZE-1, "UPDATE aclk_alert_%s SET filtered_alert_unique_id = %u where filtered_alert_unique_id = %u", uuid_str, ae->unique_id, unique_id);
+    sqlite3_exec_monitored(db_meta, sql, 0, 0, NULL);
+    ae->flags |= HEALTH_ENTRY_FLAG_ACLK_QUEUED;
+}
+
+#define MAX_REMOVED_PERIOD 86400
 //decide if some events should be sent or not
 int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
 {
@@ -56,12 +63,13 @@ int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
     uuid_t config_hash_id;
     RRDCALC_STATUS status;
     uint32_t unique_id;
-    
+
     //get the previous sent event of this alarm_id
+    //base the search on the last filtered event
     snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, "select hl.new_status, hl.config_hash_id, hl.unique_id from health_log_%s hl, aclk_alert_%s aa \
-                         where hl.unique_id = aa.alert_unique_id        \
-                         and hl.alarm_id = %u and hl.unique_id <> %u \
-                         order by alarm_event_id desc LIMIT 1;", uuid_str, uuid_str, ae->alarm_id, ae->unique_id);
+                         where hl.unique_id = aa.filtered_alert_unique_id \
+                         and hl.alarm_id = %u \
+                         order by alarm_event_id desc LIMIT 1;", uuid_str, uuid_str, ae->alarm_id);
 
     rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
     if (rc != SQLITE_OK) {
@@ -70,7 +78,7 @@ int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
         return send;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
     if (likely(rc == SQLITE_ROW)) {
         status  = (RRDCALC_STATUS) sqlite3_column_int(res, 0);
         if (sqlite3_column_type(res, 1) != SQLITE_NULL)
@@ -93,8 +101,9 @@ int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
     }
 
     //same status, same config
-    if (ae->new_status == RRDCALC_STATUS_CLEAR) {
+    if (ae->new_status == RRDCALC_STATUS_CLEAR || ae->new_status == RRDCALC_STATUS_UNDEFINED) {
         send = 0;
+        update_filtered(ae, unique_id, uuid_str);
         goto done;
     }
 
@@ -107,6 +116,7 @@ int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
             goto done;
         } else {
             send = 0;
+            update_filtered(ae, unique_id, uuid_str);
             goto done;
         }
     }
@@ -130,6 +140,8 @@ int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter)
         return 0;
     }
 
+    CHECK_SQLITE_CONNECTION(db_meta);
+
     if (!skip_filter) {
         if (!should_send_to_cloud(host, ae)) {
             return 0;
@@ -137,9 +149,6 @@ int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter)
     }
 
     int rc = 0;
-
-    CHECK_SQLITE_CONNECTION(db_meta);
-
     sqlite3_stmt *res_alert = NULL;
     char uuid_str[GUID_LEN + 1];
     uuid_unparse_lower_fix(&host->host_uuid, uuid_str);
@@ -148,8 +157,8 @@ int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter)
 
     buffer_sprintf(
         sql,
-        "INSERT INTO aclk_alert_%s (alert_unique_id, date_created) "
-        "VALUES (@alert_unique_id, unixepoch()) on conflict (alert_unique_id) do nothing; ",
+        "INSERT INTO aclk_alert_%s (alert_unique_id, date_created, filtered_alert_unique_id) "
+        "VALUES (@alert_unique_id, unixepoch(), @alert_unique_id) on conflict (alert_unique_id) do nothing; ",
         uuid_str);
 
     rc = sqlite3_prepare_v2(db_meta, buffer_tostring(sql), -1, &res_alert, 0);
@@ -220,7 +229,7 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
     int rc;
 
     if (unlikely(!wc->alert_updates)) {
-        log_access("ACLK STA [%s (%s)]: Ignoring alert push event, updates have been turned off for this node.", wc->node_id, wc->host ? wc->host->hostname : "N/A");
+        log_access("ACLK STA [%s (%s)]: Ignoring alert push event, updates have been turned off for this node.", wc->node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A");
         return;
     }
 
@@ -280,7 +289,7 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
     static __thread uint64_t log_first_sequence_id = 0;
     static __thread uint64_t log_last_sequence_id = 0;
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         struct alarm_log_entry alarm_log;
         char old_value_string[100 + 1];
         char new_value_string[100 + 1];
@@ -300,9 +309,9 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
         alarm_log.config_hash = strdupz((char *)uuid_str);
 
         alarm_log.utc_offset = wc->host->utc_offset;
-        alarm_log.timezone = strdupz((char *)wc->host->abbrev_timezone);
+        alarm_log.timezone = strdupz(rrdhost_abbrev_timezone(wc->host));
         alarm_log.exec_path = sqlite3_column_bytes(res, 14) > 0 ? strdupz((char *)sqlite3_column_text(res, 14)) :
-                                                                  strdupz((char *)wc->host->health_default_exec);
+                                                                  strdupz((char *)string2str(wc->host->health_default_exec));
         alarm_log.conf_source = strdupz((char *)sqlite3_column_text(res, 16));
 
         char *edit_command = sqlite3_column_bytes(res, 16) > 0 ?
@@ -374,7 +383,7 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
             log_access(
                 "ACLK RES [%s (%s)]: ALERTS SENT from %" PRIu64 " to %" PRIu64 " batch=%" PRIu64,
                 wc->node_id,
-                wc->host ? wc->host->hostname : "N/A",
+                wc->host ? rrdhost_hostname(wc->host) : "N/A",
                 log_first_sequence_id,
                 log_last_sequence_id,
                 wc->alerts_batch_id);
@@ -401,8 +410,8 @@ void sql_queue_existing_alerts_to_aclk(RRDHOST *host)
     BUFFER *sql = buffer_create(1024);
 
     buffer_sprintf(sql,"delete from aclk_alert_%s; " \
-                       "insert into aclk_alert_%s (alert_unique_id, date_created) " \
-                       "select unique_id alert_unique_id, unixepoch() from health_log_%s " \
+                       "insert into aclk_alert_%s (alert_unique_id, date_created, filtered_alert_unique_id) " \
+                       "select unique_id alert_unique_id, unixepoch(), unique_id alert_unique_id from health_log_%s " \
                        "where new_status <> 0 and new_status <> -2 and config_hash_id is not null and updated_by_id = 0 " \
                        "order by unique_id asc on conflict (alert_unique_id) do nothing;", uuid_str, uuid_str, uuid_str);
 
@@ -424,9 +433,7 @@ void aclk_send_alarm_health_log(char *node_id)
     struct aclk_database_worker_config *wc = find_inactive_wc_by_node_id(node_id);
 
     if (likely(!wc)) {
-        rrd_rdlock();
         RRDHOST *host = find_host_by_node_id(node_id);
-        rrd_unlock();
         if (likely(host))
             wc = (struct aclk_database_worker_config *)host->dbsync_worker;
     }
@@ -460,9 +467,7 @@ void aclk_push_alarm_health_log(struct aclk_database_worker_config *wc, struct a
 
     RRDHOST *host = wc->host;
     if (unlikely(!host)) {
-        rrd_rdlock();
         host = find_host_by_node_id(wc->node_id);
-        rrd_unlock();
 
         if (unlikely(!host)) {
             log_access(
@@ -500,7 +505,7 @@ void aclk_push_alarm_health_log(struct aclk_database_worker_config *wc, struct a
     last_timestamp.tv_sec = 0;
     last_timestamp.tv_usec = 0;
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         first_sequence = sqlite3_column_bytes(res, 0) > 0 ? (uint64_t) sqlite3_column_int64(res, 0) : 0;
         if (sqlite3_column_bytes(res, 1) > 0) {
             first_timestamp.tv_sec = sqlite3_column_int64(res, 1);
@@ -536,8 +541,6 @@ void aclk_push_alarm_health_log(struct aclk_database_worker_config *wc, struct a
 
     freez(claim_id);
     buffer_free(sql);
-
-    aclk_alert_reloaded = 1;
 #endif
 
     return;
@@ -554,7 +557,7 @@ void aclk_send_alarm_configuration(char *config_hash)
         return;
     }
 
-    log_access("ACLK REQ [%s (%s)]: Request to send alert config %s.", wc->node_id, wc->host ? wc->host->hostname : "N/A", config_hash);
+    log_access("ACLK REQ [%s (%s)]: Request to send alert config %s.", wc->node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A", config_hash);
 
     struct aclk_database_cmd cmd;
     memset(&cmd, 0, sizeof(cmd));
@@ -603,7 +606,7 @@ int aclk_push_alert_config_event(struct aclk_database_worker_config *wc, struct
     struct provide_alarm_configuration p_alarm_config;
     p_alarm_config.cfg_hash = NULL;
 
-    if (sqlite3_step(res) == SQLITE_ROW) {
+    if (sqlite3_step_monitored(res) == SQLITE_ROW) {
 
         alarm_config.alarm = sqlite3_column_bytes(res, 0) > 0 ? strdupz((char *)sqlite3_column_text(res, 0)) : NULL;
         alarm_config.tmpl = sqlite3_column_bytes(res, 1) > 0 ? strdupz((char *)sqlite3_column_text(res, 1)) : NULL;
@@ -664,14 +667,14 @@ int aclk_push_alert_config_event(struct aclk_database_worker_config *wc, struct
     }
 
     if (likely(p_alarm_config.cfg_hash)) {
-        log_access("ACLK RES [%s (%s)]: Sent alert config %s.", wc->node_id, wc->host ? wc->host->hostname : "N/A", config_hash);
+        log_access("ACLK RES [%s (%s)]: Sent alert config %s.", wc->node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A", config_hash);
         aclk_send_provide_alarm_cfg(&p_alarm_config);
         freez((char *) cmd.data_param);
         freez(p_alarm_config.cfg_hash);
         destroy_aclk_alarm_configuration(&alarm_config);
     }
     else
-        log_access("ACLK STA [%s (%s)]: Alert config for %s not found.", wc->node_id, wc->host ? wc->host->hostname : "N/A", config_hash);
+        log_access("ACLK STA [%s (%s)]: Alert config for %s not found.", wc->node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A", config_hash);
 
 bind_fail:
     rc = sqlite3_finalize(res);
@@ -697,9 +700,7 @@ void aclk_start_alert_streaming(char *node_id, uint64_t batch_id, uint64_t start
         return;
 
     struct aclk_database_worker_config *wc  = NULL;
-    rrd_rdlock();
     RRDHOST *host = find_host_by_node_id(node_id);
-    rrd_unlock();
     if (likely(host)) {
         wc = (struct aclk_database_worker_config *)host->dbsync_worker ?
                  (struct aclk_database_worker_config *)host->dbsync_worker :
@@ -716,7 +717,7 @@ void aclk_start_alert_streaming(char *node_id, uint64_t batch_id, uint64_t start
         wc = (struct aclk_database_worker_config *)find_inactive_wc_by_node_id(node_id);
 
     if (likely(wc)) {
-        log_access("ACLK REQ [%s (%s)]: ALERTS STREAM from %"PRIu64" batch=%"PRIu64, node_id, wc->host ? wc->host->hostname : "N/A", start_seq_id, batch_id);
+        log_access("ACLK REQ [%s (%s)]: ALERTS STREAM from %"PRIu64" batch=%"PRIu64, node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A", start_seq_id, batch_id);
         __sync_synchronize();
         wc->alerts_batch_id = batch_id;
         wc->alerts_start_seq_id = start_seq_id;
@@ -736,15 +737,15 @@ void sql_process_queue_removed_alerts_to_aclk(struct aclk_database_worker_config
 
     BUFFER *sql = buffer_create(1024);
 
-    buffer_sprintf(sql,"insert into aclk_alert_%s (alert_unique_id, date_created) " \
-        "select unique_id alert_unique_id, unixepoch() from health_log_%s " \
+    buffer_sprintf(sql,"insert into aclk_alert_%s (alert_unique_id, date_created, filtered_alert_unique_id) " \
+        "select unique_id alert_unique_id, unixepoch(), unique_id alert_unique_id from health_log_%s " \
         "where new_status = -2 and updated_by_id = 0 and unique_id not in " \
         "(select alert_unique_id from aclk_alert_%s) order by unique_id asc " \
         "on conflict (alert_unique_id) do nothing;", wc->uuid_str, wc->uuid_str, wc->uuid_str);
 
     db_execute(buffer_tostring(sql));
 
-    log_access("ACLK STA [%s (%s)]: QUEUED REMOVED ALERTS", wc->node_id, wc->host ? wc->host->hostname : "N/A");
+    log_access("ACLK STA [%s (%s)]: QUEUED REMOVED ALERTS", wc->node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A");
 
     buffer_free(sql);
 
@@ -780,17 +781,15 @@ void aclk_process_send_alarm_snapshot(char *node_id, char *claim_id, uint64_t sn
         return;
 
     struct aclk_database_worker_config *wc = NULL;
-    rrd_rdlock();
     RRDHOST *host = find_host_by_node_id(node_id);
     if (likely(host))
         wc = (struct aclk_database_worker_config *)host->dbsync_worker;
-    rrd_unlock();
 
     if (likely(wc)) {
         log_access(
             "IN [%s (%s)]: Request to send alerts snapshot, snapshot_id %" PRIu64 " and ack_sequence_id %" PRIu64,
             wc->node_id,
-            wc->host ? wc->host->hostname : "N/A",
+            wc->host ? rrdhost_hostname(wc->host) : "N/A",
             snapshot_id,
             sequence_id);
         if (wc->alerts_snapshot_id == snapshot_id)
@@ -831,13 +830,13 @@ void aclk_mark_alert_cloud_ack(char *uuid_str, uint64_t alerts_ack_sequence_id)
 #ifdef ENABLE_ACLK
 void health_alarm_entry2proto_nolock(struct alarm_log_entry *alarm_log, ALARM_ENTRY *ae, RRDHOST *host)
 {
-    char *edit_command = ae->source ? health_edit_command_from_source(ae->source) : strdupz("UNKNOWN=0=UNKNOWN");
+    char *edit_command = ae->source ? health_edit_command_from_source(ae_source(ae)) : strdupz("UNKNOWN=0=UNKNOWN");
     char config_hash_id[GUID_LEN + 1];
     uuid_unparse_lower(ae->config_hash_id, config_hash_id);
 
-    alarm_log->chart = strdupz((char *)ae->chart);
-    alarm_log->name = strdupz((char *)ae->name);
-    alarm_log->family = strdupz((char *)ae->family);
+    alarm_log->chart = strdupz(ae_chart_name(ae));
+    alarm_log->name = strdupz(ae_name(ae));
+    alarm_log->family = strdupz(ae_family(ae));
 
     alarm_log->batch_id = 0;
     alarm_log->sequence_id = 0;
@@ -846,9 +845,9 @@ void health_alarm_entry2proto_nolock(struct alarm_log_entry *alarm_log, ALARM_EN
     alarm_log->config_hash = strdupz((char *)config_hash_id);
 
     alarm_log->utc_offset = host->utc_offset;
-    alarm_log->timezone = strdupz((char *)host->abbrev_timezone);
-    alarm_log->exec_path = ae->exec ? strdupz((char *)ae->exec) : strdupz((char *)host->health_default_exec);
-    alarm_log->conf_source = ae->source ? strdupz((char *)ae->source) : strdupz((char *)"");
+    alarm_log->timezone = strdupz(rrdhost_abbrev_timezone(host));
+    alarm_log->exec_path = ae->exec ? strdupz(ae_exec(ae)) : strdupz((char *)string2str(host->health_default_exec));
+    alarm_log->conf_source = ae->source ? strdupz(ae_source(ae)) : strdupz((char *)"");
 
     alarm_log->command = strdupz((char *)edit_command);
 
@@ -861,31 +860,31 @@ void health_alarm_entry2proto_nolock(struct alarm_log_entry *alarm_log, ALARM_EN
     alarm_log->last_repeat = (time_t)ae->last_repeat;
 
     alarm_log->silenced =
-        ((ae->flags & HEALTH_ENTRY_FLAG_SILENCED) || (ae->recipient && !strncmp((char *)ae->recipient, "silent", 6))) ?
+        ((ae->flags & HEALTH_ENTRY_FLAG_SILENCED) || (ae->recipient && !strncmp(ae_recipient(ae), "silent", 6))) ?
             1 :
             0;
 
-    alarm_log->value_string = strdupz(ae->new_value_string);
-    alarm_log->old_value_string = strdupz(ae->old_value_string);
+    alarm_log->value_string = strdupz(ae_new_value_string(ae));
+    alarm_log->old_value_string = strdupz(ae_old_value_string(ae));
 
     alarm_log->value = (!isnan(ae->new_value)) ? (NETDATA_DOUBLE)ae->new_value : 0;
     alarm_log->old_value = (!isnan(ae->old_value)) ? (NETDATA_DOUBLE)ae->old_value : 0;
 
     alarm_log->updated = (ae->flags & HEALTH_ENTRY_FLAG_UPDATED) ? 1 : 0;
-    alarm_log->rendered_info = ae->info ? strdupz(ae->info) : strdupz((char *)"");
-    alarm_log->chart_context = ae->chart_context ? strdupz(ae->chart_context) : strdupz((char *)"");
+    alarm_log->rendered_info = strdupz(ae_info(ae));
+    alarm_log->chart_context = strdupz(ae_chart_context(ae));
 
     freez(edit_command);
 }
 #endif
 
 #ifdef ENABLE_ACLK
-static int have_recent_alarm(RRDHOST *host, uint32_t alarm_id, time_t mark)
+static int have_recent_alarm(RRDHOST *host, uint32_t alarm_id, uint32_t mark)
 {
     ALARM_ENTRY *ae = host->health_log.alarms;
 
     while (ae) {
-        if (ae->alarm_id == alarm_id && ae->unique_id > mark &&
+        if (ae->alarm_id == alarm_id && ae->unique_id >mark &&
             (ae->new_status != RRDCALC_STATUS_WARNING && ae->new_status != RRDCALC_STATUS_CRITICAL))
             return 1;
         ae = ae->next;
@@ -905,7 +904,7 @@ void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, stru
     UNUSED(cmd);
     // we perhaps we don't need this for snapshots
     if (unlikely(!wc->alert_updates)) {
-        log_access("ACLK STA [%s (%s)]: Ignoring alert snapshot event, updates have been turned off for this node.", wc->node_id, wc->host ? wc->host->hostname : "N/A");
+        log_access("ACLK STA [%s (%s)]: Ignoring alert snapshot event, updates have been turned off for this node.", wc->node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A");
         return;
     }
 
@@ -921,7 +920,7 @@ void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, stru
     if (unlikely(!claim_id))
         return;
 
-    log_access("ACLK REQ [%s (%s)]: Sending alerts snapshot, snapshot_id %" PRIu64, wc->node_id, wc->host ? wc->host->hostname : "N/A", wc->alerts_snapshot_id);
+    log_access("ACLK REQ [%s (%s)]: Sending alerts snapshot, snapshot_id %" PRIu64, wc->node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A", wc->alerts_snapshot_id);
 
     aclk_mark_alert_cloud_ack(wc->uuid_str, wc->alerts_ack_sequence_id);
 
@@ -1025,11 +1024,11 @@ void sql_aclk_alert_clean_dead_entries(RRDHOST *host)
 
     BUFFER *sql = buffer_create(1024);
 
-    buffer_sprintf(sql,"delete from aclk_alert_%s where alert_unique_id not in "
+    buffer_sprintf(sql,"delete from aclk_alert_%s where filtered_alert_unique_id not in "
                    " (select unique_id from health_log_%s); ", uuid_str, uuid_str);
     
     char *err_msg = NULL;
-    int rc = sqlite3_exec(db_meta, buffer_tostring(sql), NULL, NULL, &err_msg);
+    int rc = sqlite3_exec_monitored(db_meta, buffer_tostring(sql), NULL, NULL, &err_msg);
     if (rc != SQLITE_OK) {
         error_report("Failed when trying to clean stale ACLK alert entries from aclk_alert_%s, error message \"%s""",
                      uuid_str, err_msg);
@@ -1064,7 +1063,7 @@ int get_proto_alert_status(RRDHOST *host, struct proto_alert_status *proto_alert
         return 1;
     }
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         proto_alert_status->pending_min_sequence_id = sqlite3_column_bytes(res, 0) > 0 ? (uint64_t) sqlite3_column_int64(res, 0) : 0;
         proto_alert_status->pending_max_sequence_id = sqlite3_column_bytes(res, 1) > 0 ? (uint64_t) sqlite3_column_int64(res, 1) : 0;
         proto_alert_status->last_acked_sequence_id = sqlite3_column_bytes(res, 2) > 0 ? (uint64_t) sqlite3_column_int64(res, 2) : 0;
diff --git a/database/sqlite/sqlite_aclk_alert.h b/database/sqlite/sqlite_aclk_alert.h
index 0181b4842..88a939e87 100644
--- a/database/sqlite/sqlite_aclk_alert.h
+++ b/database/sqlite/sqlite_aclk_alert.h
@@ -26,6 +26,6 @@ void sql_process_queue_removed_alerts_to_aclk(struct aclk_database_worker_config
 void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
 void aclk_process_send_alarm_snapshot(char *node_id, char *claim_id, uint64_t snapshot_id, uint64_t sequence_id);
 int get_proto_alert_status(RRDHOST *host, struct proto_alert_status *proto_alert_status);
-extern int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter);
+int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter);
 
 #endif //NETDATA_SQLITE_ACLK_ALERT_H
diff --git a/database/sqlite/sqlite_aclk_chart.c b/database/sqlite/sqlite_aclk_chart.c
deleted file mode 100644
index c1db60c49..000000000
--- a/database/sqlite/sqlite_aclk_chart.c
+++ /dev/null
@@ -1,1311 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#include "sqlite_functions.h"
-#include "sqlite_aclk_chart.h"
-
-#ifdef ENABLE_ACLK
-#include "../../aclk/aclk_charts_api.h"
-#include "../../aclk/aclk.h"
-
-static inline int
-sql_queue_chart_payload(struct aclk_database_worker_config *wc, void *data, enum aclk_database_opcode opcode)
-{
-    int rc;
-    if (unlikely(!wc))
-        return 1;
-
-    struct aclk_database_cmd cmd;
-    memset(&cmd, 0, sizeof(cmd));
-    cmd.opcode = opcode;
-    cmd.data = data;
-    rc = aclk_database_enq_cmd_noblock(wc, &cmd);
-    return rc;
-}
-
-static time_t payload_sent(char *uuid_str, uuid_t *uuid, void *payload, size_t payload_size)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-    time_t send_status = 0;
-
-    if (unlikely(!res)) {
-        char sql[ACLK_SYNC_QUERY_SIZE];
-        snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, "SELECT acl.date_submitted FROM aclk_chart_latest_%s acl, aclk_chart_payload_%s acp "
-            "WHERE acl.unique_id = acp.unique_id AND acl.uuid = @uuid AND acp.payload = @payload;",
-                  uuid_str, uuid_str);
-        rc = prepare_statement(db_meta, sql, &res);
-        if (rc != SQLITE_OK) {
-            error_report("Failed to prepare statement to check payload data on %s", sql);
-            return 0;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, uuid, sizeof(*uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_blob(res, 2, payload, payload_size, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    while (sqlite3_step(res) == SQLITE_ROW) {
-        send_status = (time_t) sqlite3_column_int64(res, 0);
-    }
-
-bind_fail:
-    if (unlikely(sqlite3_reset(res) != SQLITE_OK))
-        error_report("Failed to reset statement in check payload, rc = %d", rc);
-    return send_status;
-}
-
-static int aclk_add_chart_payload(
-    struct aclk_database_worker_config *wc,
-    uuid_t *uuid,
-    char *claim_id,
-    ACLK_PAYLOAD_TYPE payload_type,
-    void *payload,
-    size_t payload_size,
-    time_t *send_status,
-    int check_sent)
-{
-    static __thread sqlite3_stmt *res_chart = NULL;
-    int rc;
-    time_t date_submitted;
-
-    if (unlikely(!payload))
-        return 0;
-
-    if (check_sent) {
-        date_submitted = payload_sent(wc->uuid_str, uuid, payload, payload_size);
-        if (send_status)
-            *send_status = date_submitted;
-        if (date_submitted)
-            return 0;
-    }
-
-    if (unlikely(!res_chart)) {
-        char sql[ACLK_SYNC_QUERY_SIZE];
-        snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1,
-                  "INSERT INTO aclk_chart_payload_%s (unique_id, uuid, claim_id, date_created, type, payload) " \
-                  "VALUES (@unique_id, @uuid, @claim_id, unixepoch(), @type, @payload);", wc->uuid_str);
-        rc = prepare_statement(db_meta, sql, &res_chart);
-        if (rc != SQLITE_OK) {
-            error_report("Failed to prepare statement to store chart payload data");
-            return 1;
-        }
-    }
-
-    uuid_t unique_uuid;
-    uuid_generate(unique_uuid);
-
-    uuid_t claim_uuid;
-    if (uuid_parse(claim_id, claim_uuid))
-        return 1;
-
-    rc = sqlite3_bind_blob(res_chart, 1, &unique_uuid, sizeof(unique_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_blob(res_chart, 2, uuid, sizeof(*uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_blob(res_chart, 3, &claim_uuid, sizeof(claim_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res_chart, 4, payload_type);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_blob(res_chart, 5, payload, payload_size, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = execute_insert(res_chart);
-    if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed store chart payload event, rc = %d", rc);
-    else {
-        wc->chart_payload_count++;
-        time_t now = now_realtime_sec();
-        if (wc->rotation_after > now && wc->rotation_after < now + ACLK_DATABASE_ROTATION_DELAY)
-            wc->rotation_after = now + ACLK_DATABASE_ROTATION_DELAY;
-    }
-
-bind_fail:
-    if (unlikely(sqlite3_reset(res_chart) != SQLITE_OK))
-        error_report("Failed to reset statement in store chart payload, rc = %d", rc);
-    return (rc != SQLITE_DONE);
-}
-
-int aclk_add_chart_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    int rc = 0;
-    CHECK_SQLITE_CONNECTION(db_meta);
-
-    char *claim_id = get_agent_claimid();
-
-    RRDSET *st = cmd.data;
-
-    if (likely(claim_id)) {
-        struct chart_instance_updated chart_payload;
-        memset(&chart_payload, 0, sizeof(chart_payload));
-        chart_payload.config_hash = get_str_from_uuid(&st->state->hash_id);
-        chart_payload.update_every = st->update_every;
-        chart_payload.memory_mode = st->rrd_memory_mode;
-        chart_payload.name = (char *)st->name;
-        chart_payload.node_id = wc->node_id;
-        chart_payload.claim_id = claim_id;
-        chart_payload.id = strdupz(st->id);
-
-        chart_payload.chart_labels = rrdlabels_create();
-        rrdlabels_copy(chart_payload.chart_labels, st->state->chart_labels);
-
-        size_t size;
-        char *payload = generate_chart_instance_updated(&size, &chart_payload);
-        if (likely(payload))
-            rc = aclk_add_chart_payload(wc, st->chart_uuid, claim_id, ACLK_PAYLOAD_CHART, (void *) payload, size, NULL, 1);
-        freez(payload);
-        chart_instance_updated_destroy(&chart_payload);
-    }
-    return rc;
-}
-
-static inline int aclk_upd_dimension_event(struct aclk_database_worker_config *wc, char *claim_id, uuid_t *dim_uuid,
-        const char *dim_id, const char *dim_name, const char *chart_type_id, time_t first_time, time_t last_time,
-        time_t *send_status)
-{
-    int rc = 0;
-    size_t size;
-
-    if (unlikely(!dim_uuid || !dim_id || !dim_name || !chart_type_id))
-        return 0;
-
-    struct chart_dimension_updated dim_payload;
-    memset(&dim_payload, 0, sizeof(dim_payload));
-
-#ifdef NETDATA_INTERNAL_CHECKS
-    if (!first_time)
-        info("Host %s (node %s) deleting dimension id=[%s] name=[%s] chart=[%s]",
-                wc->host_guid, wc->node_id, dim_id, dim_name, chart_type_id);
-    if (last_time)
-        info("Host %s (node %s) stopped collecting dimension id=[%s] name=[%s] chart=[%s] %ld seconds ago at %ld",
-             wc->host_guid, wc->node_id, dim_id, dim_name, chart_type_id, now_realtime_sec() - last_time, last_time);
-#endif
-
-    dim_payload.node_id = wc->node_id;
-    dim_payload.claim_id = claim_id;
-    dim_payload.name = dim_name;
-    dim_payload.id = dim_id;
-    dim_payload.chart_id = chart_type_id;
-    dim_payload.created_at.tv_sec = first_time;
-    dim_payload.last_timestamp.tv_sec = last_time;
-    char *payload = generate_chart_dimension_updated(&size, &dim_payload);
-    if (likely(payload))
-        rc = aclk_add_chart_payload(wc, dim_uuid, claim_id, ACLK_PAYLOAD_DIMENSION, (void *)payload, size, send_status, 1);
-    freez(payload);
-    return rc;
-}
-
-void aclk_process_dimension_deletion(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    int rc = 0;
-    sqlite3_stmt *res = NULL;
-
-    if (!aclk_connected)
-        return;
-
-    if (unlikely(!db_meta))
-        return;
-
-    uuid_t host_id;
-    if (uuid_parse(wc->host_guid, host_id))
-        return;
-
-    char *claim_id = get_agent_claimid();
-    if (!claim_id)
-        return;
-
-    rc = sqlite3_prepare_v2(
-        db_meta,
-        "DELETE FROM dimension_delete where host_id = @host_id "
-        "RETURNING dimension_id, dimension_name, chart_type_id, dim_id LIMIT 10;",
-        -1,
-        &res,
-        0);
-
-    if (rc != SQLITE_OK) {
-        error_report("Failed to prepare statement when trying to delete dimension deletes");
-        freez(claim_id);
-        return;
-    }
-
-    rc = sqlite3_bind_blob(res, 1, &host_id, sizeof(host_id), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    unsigned count = 0;
-    while (sqlite3_step(res) == SQLITE_ROW) {
-        (void) aclk_upd_dimension_event(
-            wc,
-            claim_id,
-            (uuid_t *)sqlite3_column_text(res, 3),
-            (const char *)sqlite3_column_text(res, 0),
-            (const char *)sqlite3_column_text(res, 1),
-            (const char *)sqlite3_column_text(res, 2),
-            0,
-            0,
-            NULL);
-        count++;
-    }
-
-    if (count) {
-        memset(&cmd, 0, sizeof(cmd));
-        cmd.opcode = ACLK_DATABASE_DIM_DELETION;
-        if (aclk_database_enq_cmd_noblock(wc, &cmd))
-            info("Failed to queue a dimension deletion message");
-    }
-
-bind_fail:
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize statement when adding dimension deletion events, rc = %d", rc);
-    freez(claim_id);
-    return;
-}
-
-int aclk_add_dimension_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    int rc = 1;
-    CHECK_SQLITE_CONNECTION(db_meta);
-
-    struct aclk_chart_dimension_data *aclk_cd_data = cmd.data;
-
-    char *claim_id = get_agent_claimid();
-    if (!claim_id)
-        goto cleanup;
-
-    rc = aclk_add_chart_payload(wc, &aclk_cd_data->uuid, claim_id, ACLK_PAYLOAD_DIMENSION,
-              (void *) aclk_cd_data->payload, aclk_cd_data->payload_size, NULL, aclk_cd_data->check_payload);
-
-    freez(claim_id);
-cleanup:
-    freez(aclk_cd_data->payload);
-    freez(aclk_cd_data);
-    return rc;
-}
-
-void aclk_send_chart_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    int rc;
-
-    wc->chart_pending = 0;
-    if (unlikely(!wc->chart_updates)) {
-        log_access(
-            "ACLK STA [%s (%s)]: Ignoring chart push event, updates have been turned off for this node.",
-            wc->node_id,
-            wc->host ? wc->host->hostname : "N/A");
-        return;
-    }
-
-    char *claim_id = get_agent_claimid();
-    if (unlikely(!claim_id))
-        return;
-
-    uuid_t claim_uuid;
-    if (uuid_parse(claim_id, claim_uuid))
-        return;
-
-    int limit = cmd.count > 0 ? cmd.count : 1;
-
-    uint64_t first_sequence;
-    uint64_t last_sequence;
-    time_t last_timestamp = 0;
-
-    char sql[ACLK_SYNC_QUERY_SIZE];
-    static __thread sqlite3_stmt *res = NULL;
-
-    if (unlikely(!res)) {
-        snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1,"SELECT ac.sequence_id, acp.payload, ac.date_created, ac.type, ac.uuid  " \
-             "FROM aclk_chart_%s ac, aclk_chart_payload_%s acp " \
-             "WHERE ac.date_submitted IS NULL AND ac.unique_id = acp.unique_id AND ac.update_count > 0 " \
-             "AND acp.claim_id = @claim_id ORDER BY ac.sequence_id ASC LIMIT %d;", wc->uuid_str, wc->uuid_str, limit);
-        rc = prepare_statement(db_meta, sql, &res);
-        if (rc != SQLITE_OK) {
-            error_report("Failed to prepare statement when trying to send a chart update via ACLK");
-            freez(claim_id);
-            return;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, claim_uuid, sizeof(claim_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    char **payload_list = callocz(limit + 1, sizeof(char *));
-    size_t *payload_list_size = callocz(limit + 1, sizeof(size_t));
-    size_t *payload_list_max_size = callocz(limit + 1, sizeof(size_t));
-    struct aclk_message_position *position_list = callocz(limit + 1, sizeof(*position_list));
-    int *is_dim = callocz(limit + 1, sizeof(*is_dim));
-
-    int loop = cmd.param1;
-
-    uint64_t start_sequence_id = wc->chart_sequence_id;
-
-    while (loop > 0) {
-        uint64_t previous_sequence_id = wc->chart_sequence_id;
-        int count = 0;
-        first_sequence = 0;
-        last_sequence = 0;
-        while (count < limit && sqlite3_step(res) == SQLITE_ROW) {
-            size_t payload_size = sqlite3_column_bytes(res, 1);
-            if (payload_list_max_size[count] < payload_size) {
-                freez(payload_list[count]);
-                payload_list_max_size[count] = payload_size;
-                payload_list[count] = mallocz(payload_size);
-            }
-            payload_list_size[count] = payload_size;
-            memcpy(payload_list[count], sqlite3_column_blob(res, 1), payload_size);
-            position_list[count].sequence_id = (uint64_t)sqlite3_column_int64(res, 0);
-            position_list[count].previous_sequence_id = previous_sequence_id;
-            position_list[count].seq_id_creation_time.tv_sec = sqlite3_column_int64(res, 2);
-            position_list[count].seq_id_creation_time.tv_usec = 0;
-            if (!first_sequence)
-                first_sequence = position_list[count].sequence_id;
-            last_sequence = position_list[count].sequence_id;
-            last_timestamp = position_list[count].seq_id_creation_time.tv_sec;
-            previous_sequence_id = last_sequence;
-            is_dim[count] = sqlite3_column_int(res, 3) > 0;
-            count++;
-            if (wc->chart_payload_count)
-                wc->chart_payload_count--;
-        }
-        freez(payload_list[count]);
-        payload_list_max_size[count] = 0;
-        payload_list[count] = NULL;
-
-        rc = sqlite3_reset(res);
-        if (unlikely(rc != SQLITE_OK))
-            error_report("Failed to reset statement when pushing chart events, rc = %d", rc);
-
-        if (likely(first_sequence)) {
-
-            db_lock();
-            snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, "UPDATE aclk_chart_%s SET status = NULL, date_submitted=unixepoch() "
-                                "WHERE date_submitted IS NULL AND sequence_id BETWEEN %" PRIu64 " AND %" PRIu64 ";",
-                                wc->uuid_str, first_sequence, last_sequence);
-            db_execute(sql);
-            snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, "INSERT OR REPLACE INTO aclk_chart_latest_%s (uuid, unique_id, date_submitted) "
-                                " SELECT uuid, unique_id, date_submitted FROM aclk_chart_%s s "
-                                " WHERE date_submitted IS NOT NULL AND sequence_id BETWEEN %" PRIu64 " AND %" PRIu64
-                                " ;",
-                                wc->uuid_str, wc->uuid_str, first_sequence, last_sequence);
-            db_execute(sql);
-            db_unlock();
-
-            aclk_chart_inst_and_dim_update(payload_list, payload_list_size, is_dim, position_list, wc->batch_id);
-            log_access(
-                "ACLK RES [%s (%s)]: CHARTS SENT from %" PRIu64 " to %" PRIu64 " batch=%" PRIu64,
-                wc->node_id,
-                wc->hostname ? wc->hostname : "N/A",
-                first_sequence,
-                last_sequence,
-                wc->batch_id);
-            wc->chart_sequence_id = last_sequence;
-            wc->chart_timestamp = last_timestamp;
-        } else
-            break;
-        --loop;
-    }
-
-    if (start_sequence_id != wc->chart_sequence_id) {
-        time_t now = now_realtime_sec();
-        if (wc->rotation_after > now && wc->rotation_after < now + ACLK_DATABASE_ROTATION_DELAY)
-            wc->rotation_after = now + ACLK_DATABASE_ROTATION_DELAY;
-    } else {
-        wc->chart_payload_count = sql_get_pending_count(wc);
-        if (!wc->chart_payload_count)
-            log_access(
-                "ACLK STA [%s (%s)]: Sync of charts and dimensions done in %ld seconds.",
-                wc->node_id,
-                wc->hostname ? wc->hostname : "N/A",
-                now_realtime_sec() - wc->startup_time);
-    }
-
-    for (int i = 0; i <= limit; ++i)
-        freez(payload_list[i]);
-
-    freez(payload_list);
-    freez(payload_list_size);
-    freez(payload_list_max_size);
-    freez(position_list);
-    freez(is_dim);
-
-bind_fail:
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement when pushing chart events, rc = %d", rc);
-
-    freez(claim_id);
-    return;
-}
-
-// Push one chart config to the cloud
-int aclk_send_chart_config(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    UNUSED(wc);
-
-    CHECK_SQLITE_CONNECTION(db_meta);
-
-    sqlite3_stmt *res = NULL;
-    int rc = 0;
-
-    char *hash_id = (char *) cmd.data_param;
-
-    uuid_t hash_uuid;
-    rc = uuid_parse(hash_id, hash_uuid);
-
-    if (unlikely(rc)) {
-        freez((char *) cmd.data_param);
-        return 1;
-    }
-
-    BUFFER *sql = buffer_create(1024);
-    buffer_sprintf(sql, "SELECT type, family, context, title, priority, plugin, module, unit, chart_type " \
-    "FROM chart_hash WHERE hash_id = @hash_id;");
-
-    rc = sqlite3_prepare_v2(db_meta, buffer_tostring(sql), -1, &res, 0);
-    if (rc != SQLITE_OK) {
-        error_report("Failed to prepare statement when trying to fetch a chart hash configuration");
-        goto fail;
-    }
-
-    rc = sqlite3_bind_blob(res, 1, &hash_uuid , sizeof(hash_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    struct chart_config_updated chart_config;
-    chart_config.config_hash  = NULL;
-
-    while (sqlite3_step(res) == SQLITE_ROW) {
-        chart_config.type = strdupz((char *)sqlite3_column_text(res, 0));
-        chart_config.family = strdupz((char *)sqlite3_column_text(res, 1));
-        chart_config.context = strdupz((char *)sqlite3_column_text(res, 2));
-        chart_config.title = strdupz((char *)sqlite3_column_text(res, 3));
-        chart_config.priority = sqlite3_column_int64(res, 4);
-        chart_config.plugin = strdupz((char *)sqlite3_column_text(res, 5));
-        chart_config.module = sqlite3_column_bytes(res, 6) > 0 ? strdupz((char *)sqlite3_column_text(res, 6)) : NULL;
-        chart_config.chart_type = (RRDSET_TYPE) sqlite3_column_int(res,8);
-        chart_config.units = strdupz((char *)sqlite3_column_text(res, 7));
-        chart_config.config_hash = strdupz(hash_id);
-    }
-
-    if (likely(chart_config.config_hash)) {
-        log_access(
-            "ACLK REQ [%s (%s)]: Sending chart config for %s.",
-            wc->node_id,
-            wc->host ? wc->host->hostname : "N/A",
-            hash_id);
-        aclk_chart_config_updated(&chart_config, 1);
-        destroy_chart_config_updated(&chart_config);
-    } else
-        log_access(
-            "ACLK STA [%s (%s)]: Chart config for %s not found.",
-            wc->node_id,
-            wc->host ? wc->host->hostname : "N/A",
-            hash_id);
-
-bind_fail:
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement when pushing chart config hash, rc = %d", rc);
-fail:
-    freez((char *)cmd.data_param);
-    buffer_free(sql);
-    return rc;
-}
-
-void aclk_receive_chart_ack(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    int rc;
-    sqlite3_stmt *res = NULL;
-
-    char sql[ACLK_SYNC_QUERY_SIZE];
-
-    snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1,"UPDATE aclk_chart_%s SET date_updated=unixepoch() WHERE sequence_id <= @sequence_id "
-            "AND date_submitted IS NOT NULL AND date_updated IS NULL;", wc->uuid_str);
-
-    rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
-    if (rc != SQLITE_OK) {
-        error_report("Failed to prepare statement to ack chart sequence ids");
-        return;
-    }
-
-    rc = sqlite3_bind_int64(res, 1, (uint64_t) cmd.param1);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = execute_insert(res);
-    if (rc != SQLITE_DONE)
-        error_report("Failed to ACK sequence id, rc = %d", rc);
-    else
-        log_access(
-            "ACLK STA [%s (%s)]: CHARTS ACKNOWLEDGED IN THE DATABASE UP TO %" PRIu64,
-            wc->node_id,
-            wc->host ? wc->host->hostname : "N/A",
-            cmd.param1);
-
-bind_fail:
-    if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
-        error_report("Failed to finalize statement to ACK older sequence ids, rc = %d", rc);
-    return;
-}
-
-void aclk_receive_chart_reset(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    BUFFER *sql = buffer_create(1024);
-    buffer_sprintf(
-        sql,
-        "UPDATE aclk_chart_%s SET status = NULL, date_submitted = NULL WHERE sequence_id >= %" PRIu64 ";",
-        wc->uuid_str,
-        cmd.param1);
-    db_execute(buffer_tostring(sql));
-    if (cmd.param1 == 1) {
-        buffer_flush(sql);
-        log_access("ACLK REQ [%s (%s)]: Received chart full resync.", wc->node_id, wc->hostname ? wc->hostname: "N/A");
-        buffer_sprintf(sql, "DELETE FROM aclk_chart_payload_%s; DELETE FROM aclk_chart_%s; " \
-                            "DELETE FROM aclk_chart_latest_%s;", wc->uuid_str, wc->uuid_str, wc->uuid_str);
-        db_lock();
-
-        db_execute("BEGIN TRANSACTION;");
-        db_execute(buffer_tostring(sql));
-        db_execute("COMMIT TRANSACTION;");
-
-        db_unlock();
-        wc->chart_sequence_id = 0;
-        wc->chart_timestamp = 0;
-        wc->chart_payload_count = 0;
-
-        RRDHOST *host = wc->host;
-        if (likely(host)) {
-            rrdhost_rdlock(host);
-            RRDSET *st;
-            rrdset_foreach_read(st, host)
-            {
-                rrdset_rdlock(st);
-                rrdset_flag_clear(st, RRDSET_FLAG_ACLK);
-                RRDDIM *rd;
-                rrddim_foreach_read(rd, st)
-                {
-                    rrddim_flag_clear(rd, RRDDIM_FLAG_ACLK);
-                    rd->aclk_live_status = (rd->aclk_live_status == 0);
-                }
-                rrdset_unlock(st);
-            }
-            rrdhost_unlock(host);
-        } else
-            error_report("ACLK synchronization thread for %s is not linked to HOST", wc->host_guid);
-    } else {
-        log_access(
-            "ACLK STA [%s (%s)]: RESTARTING CHART SYNC FROM SEQUENCE %" PRIu64,
-            wc->node_id,
-            wc->hostname ? wc->hostname : "N/A",
-            cmd.param1);
-        wc->chart_payload_count = sql_get_pending_count(wc);
-        sql_get_last_chart_sequence(wc);
-    }
-    buffer_free(sql);
-    wc->chart_updates = 1;
-    return;
-}
-
-//
-// Functions called directly from ACLK threads and will queue commands
-//
-void aclk_get_chart_config(char **hash_id)
-{
-    struct aclk_database_worker_config *wc = (struct aclk_database_worker_config *)localhost->dbsync_worker;
-
-    if (unlikely(!wc || !hash_id))
-        return;
-
-    struct aclk_database_cmd cmd;
-    memset(&cmd, 0, sizeof(cmd));
-    cmd.opcode = ACLK_DATABASE_PUSH_CHART_CONFIG;
-    for (int i = 0; hash_id[i]; ++i) {
-        // TODO: Verify that we have a valid hash_id
-        log_access(
-            "ACLK REQ [%s (%s)]: Request %d for chart config with hash %s received.",
-            wc->node_id,
-            wc->host ? wc->host->hostname : "N/A",
-            i,
-            hash_id[i]);
-        cmd.data_param = (void *)strdupz(hash_id[i]);
-        aclk_database_enq_cmd(wc, &cmd);
-    }
-    return;
-}
-
-// Send a command to a node_id
-// Need to discover the thread that will handle the request
-// if thread not in active hosts, then try to find in the queue
-static void aclk_submit_param_command(char *node_id, enum aclk_database_opcode aclk_command, uint64_t param)
-{
-    if (unlikely(!node_id))
-        return;
-
-    struct aclk_database_worker_config *wc = NULL;
-    struct aclk_database_cmd cmd;
-    memset(&cmd, 0, sizeof(cmd));
-    cmd.opcode = aclk_command;
-    cmd.param1 = param;
-
-    rrd_rdlock();
-    RRDHOST *host = find_host_by_node_id(node_id);
-    if (likely(host))
-        wc = (struct aclk_database_worker_config *)host->dbsync_worker;
-    rrd_unlock();
-    if (wc)
-        aclk_database_enq_cmd(wc, &cmd);
-    else {
-        if (aclk_worker_enq_cmd(node_id, &cmd))
-            log_access("ACLK STA [%s (N/A)]: ACLK synchronization thread is not active.", node_id);
-    }
-    return;
-}
-
-void aclk_ack_chart_sequence_id(char *node_id, uint64_t last_sequence_id)
-{
-    if (unlikely(!node_id))
-        return;
-
-    char *hostname = get_hostname_by_node_id(node_id);
-    log_access("ACLK REQ [%s (%s)]: CHARTS ACKNOWLEDGED upto %" PRIu64, node_id, hostname ? hostname : "N/A",
-               last_sequence_id);
-    freez(hostname);
-    aclk_submit_param_command(node_id, ACLK_DATABASE_CHART_ACK, last_sequence_id);
-    return;
-}
-
-// Start streaming charts / dimensions for node_id
-void aclk_start_streaming(char *node_id, uint64_t sequence_id, time_t created_at, uint64_t batch_id)
-{
-    UNUSED(created_at);
-    if (unlikely(!node_id))
-        return;
-
-    uuid_t node_uuid;
-    if (uuid_parse(node_id, node_uuid)) {
-        log_access("ACLK REQ [%s (N/A)]: CHARTS STREAM ignored, invalid node id", node_id);
-        return;
-    }
-
-    struct aclk_database_worker_config *wc  = find_inactive_wc_by_node_id(node_id);
-    rrd_rdlock();
-    RRDHOST *host = localhost;
-    while(host) {
-        if (wc || (host->node_id && !(uuid_compare(*host->node_id, node_uuid)))) {
-            rrd_unlock();
-            if (!wc)
-                wc = (struct aclk_database_worker_config *)host->dbsync_worker ?
-                         (struct aclk_database_worker_config *)host->dbsync_worker :
-                         (struct aclk_database_worker_config *)find_inactive_wc_by_node_id(node_id);
-            if (likely(wc)) {
-                wc->chart_reset_count++;
-                __sync_synchronize();
-                wc->chart_updates = 0;
-                wc->batch_id = batch_id;
-                __sync_synchronize();
-                wc->batch_created = now_realtime_sec();
-                log_access(
-                    "ACLK REQ [%s (%s)]: CHARTS STREAM from %"PRIu64" (LOCAL %"PRIu64") t=%ld resets=%d" ,
-                    wc->node_id,
-                    wc->hostname ? wc->hostname : "N/A",
-                    sequence_id + 1,
-                    wc->chart_sequence_id,
-                    wc->chart_timestamp,
-                    wc->chart_reset_count);
-                if (sequence_id > wc->chart_sequence_id || wc->chart_reset_count > 10) {
-                    log_access(
-                        "ACLK RES [%s (%s)]: CHARTS FULL RESYNC REQUEST "
-                        "remote_seq=%" PRIu64 " local_seq=%" PRIu64 " resets=%d ",
-                        wc->node_id,
-                        wc->hostname ? wc->hostname : "N/A",
-                        sequence_id,
-                        wc->chart_sequence_id,
-                        wc->chart_reset_count);
-
-                    chart_reset_t chart_reset;
-                    chart_reset.claim_id = get_agent_claimid();
-                    if (chart_reset.claim_id) {
-                        chart_reset.node_id = node_id;
-                        chart_reset.reason = SEQ_ID_NOT_EXISTS;
-                        aclk_chart_reset(chart_reset);
-                        freez(chart_reset.claim_id);
-                        wc->chart_reset_count = -1;
-                    }
-                } else {
-                    struct aclk_database_cmd cmd;
-                    memset(&cmd, 0, sizeof(cmd));
-                    // TODO: handle timestamp
-                    if (sequence_id < wc->chart_sequence_id ||
-                        !sequence_id) { // || created_at != wc->chart_timestamp) {
-                        log_access(
-                            "ACLK REQ [%s (%s)]: CHART RESET from %" PRIu64 " t=%ld batch=%" PRIu64,
-                            wc->node_id,
-                            wc->hostname ? wc->hostname : "N/A",
-                            sequence_id + 1,
-                            wc->chart_timestamp,
-                            wc->batch_id);
-                        cmd.opcode = ACLK_DATABASE_RESET_CHART;
-                        cmd.param1 = sequence_id + 1;
-                        cmd.completion = NULL;
-                        aclk_database_enq_cmd(wc, &cmd);
-                    } else {
-                        wc->chart_reset_count = 0;
-                        wc->chart_updates = 1;
-                    }
-                }
-            } else {
-                log_access("ACLK STA [%s (%s)]: ACLK synchronization thread is not active.", node_id, wc->hostname ? wc->hostname : "N/A");
-            }
-            return;
-        }
-        host = host->next;
-    }
-    rrd_unlock();
-    return;
-}
-
-#define SQL_SELECT_HOST_MEMORY_MODE "SELECT memory_mode FROM chart WHERE host_id = @host_id LIMIT 1;"
-
-static RRD_MEMORY_MODE sql_get_host_memory_mode(uuid_t *host_id)
-{
-    int rc;
-
-    RRD_MEMORY_MODE memory_mode = RRD_MEMORY_MODE_RAM;
-    sqlite3_stmt *res = NULL;
-
-    rc = sqlite3_prepare_v2(db_meta, SQL_SELECT_HOST_MEMORY_MODE, -1, &res, 0);
-
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to read host memory mode");
-        return memory_mode;
-    }
-
-    rc = sqlite3_bind_blob(res, 1, host_id, sizeof(*host_id), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind host parameter to fetch host memory mode");
-        goto failed;
-    }
-
-    while (sqlite3_step(res) == SQLITE_ROW) {
-        memory_mode = (RRD_MEMORY_MODE)sqlite3_column_int(res, 0);
-    }
-
-failed:
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize the prepared statement when reading host memory mode");
-    return memory_mode;
-}
-
-#define SELECT_HOST_DIMENSION_LIST                                                                                     \
-    "SELECT d.dim_id, c.update_every, c.type||'.'||c.id, d.id, d.name FROM chart c, dimension d "                      \
-    "WHERE d.chart_id = c.chart_id AND c.host_id = @host_id ORDER BY c.update_every ASC;"
-
-#define SELECT_HOST_CHART_LIST                                                                                         \
-    "SELECT distinct h.host_id, c.update_every, c.type||'.'||c.id FROM chart c, host h "                               \
-    "WHERE c.host_id = h.host_id AND c.host_id = @host_id ORDER BY c.update_every ASC;"
-
-void aclk_update_retention(struct aclk_database_worker_config *wc)
-{
-    int rc;
-
-    if (!aclk_connected)
-        return;
-
-    if (wc->host && rrdhost_flag_check(wc->host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS)) {
-        internal_error(true, "Skipping aclk_update_retention for host %s because context streaming is enabled", wc->host->hostname);
-        return;
-    }
-
-    char *claim_id = get_agent_claimid();
-    if (unlikely(!claim_id))
-        return;
-
-    sqlite3_stmt *res = NULL;
-    RRD_MEMORY_MODE memory_mode;
-
-    uuid_t host_uuid;
-    rc = uuid_parse(wc->host_guid, host_uuid);
-    if (unlikely(rc)) {
-        freez(claim_id);
-        return;
-    }
-
-    if (wc->host)
-        memory_mode = wc->host->rrd_memory_mode;
-    else
-        memory_mode = sql_get_host_memory_mode(&host_uuid);
-
-    if (memory_mode == RRD_MEMORY_MODE_DBENGINE)
-        rc = sqlite3_prepare_v2(db_meta, SELECT_HOST_DIMENSION_LIST, -1, &res, 0);
-    else
-        rc = sqlite3_prepare_v2(db_meta, SELECT_HOST_CHART_LIST, -1, &res, 0);
-
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to fetch host dimensions");
-        freez(claim_id);
-        return;
-    }
-
-    rc = sqlite3_bind_blob(res, 1, &host_uuid, sizeof(host_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind host parameter to fetch host dimensions");
-        goto failed;
-    }
-
-    time_t start_time = LONG_MAX;
-    time_t first_entry_t;
-    time_t last_entry_t;
-    uint32_t update_every = 0;
-    uint32_t dimension_update_count = 0;
-    uint32_t total_checked = 0;
-    uint32_t total_deleted= 0;
-    uint32_t total_stopped= 0;
-    time_t send_status;
-
-    struct retention_updated rotate_data;
-
-    memset(&rotate_data, 0, sizeof(rotate_data));
-
-    int max_intervals = 32;
-
-    rotate_data.interval_duration_count = 0;
-    rotate_data.interval_durations = callocz(max_intervals, sizeof(*rotate_data.interval_durations));
-
-    now_realtime_timeval(&rotate_data.rotation_timestamp);
-    rotate_data.memory_mode = memory_mode;
-    rotate_data.claim_id = claim_id;
-    rotate_data.node_id = strdupz(wc->node_id);
-
-    time_t now = now_realtime_sec();
-    while (sqlite3_step(res) == SQLITE_ROW && dimension_update_count < ACLK_MAX_DIMENSION_CLEANUP) {
-        if (unlikely(netdata_exit))
-            break;
-        if (!update_every || update_every != (uint32_t)sqlite3_column_int(res, 1)) {
-            if (update_every) {
-                debug(D_ACLK_SYNC, "Update %s for %u oldest time = %ld", wc->host_guid, update_every, start_time);
-                if (start_time == LONG_MAX)
-                    rotate_data.interval_durations[rotate_data.interval_duration_count].retention = 0;
-                else
-                    rotate_data.interval_durations[rotate_data.interval_duration_count].retention =
-                        rotate_data.rotation_timestamp.tv_sec - start_time;
-                rotate_data.interval_duration_count++;
-            }
-            update_every = (uint32_t)sqlite3_column_int(res, 1);
-            rotate_data.interval_durations[rotate_data.interval_duration_count].update_every = update_every;
-            start_time = LONG_MAX;
-        }
-#ifdef ENABLE_DBENGINE
-        if (memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            rc =
-                rrdeng_metric_latest_time_by_uuid((uuid_t *)sqlite3_column_blob(res, 0), &first_entry_t, &last_entry_t, 0);
-        else
-#endif
-        {
-            if (wc->host) {
-                RRDSET *st = NULL;
-                rc = (st = rrdset_find(wc->host, (const char *)sqlite3_column_text(res, 2))) ? 0 : 1;
-                if (!rc) {
-                    first_entry_t = rrdset_first_entry_t(st);
-                    last_entry_t = rrdset_last_entry_t(st);
-                }
-            } else {
-                rc = 0;
-                first_entry_t = rotate_data.rotation_timestamp.tv_sec;
-            }
-        }
-
-        if (likely(!rc && first_entry_t))
-            start_time = MIN(start_time, first_entry_t);
-
-        if (memory_mode == RRD_MEMORY_MODE_DBENGINE && wc->chart_updates && (dimension_update_count < ACLK_MAX_DIMENSION_CLEANUP)) {
-            int live = ((now - last_entry_t) < (RRDSET_MINIMUM_DIM_LIVE_MULTIPLIER * update_every));
-            if (rc) {
-                first_entry_t = 0;
-                last_entry_t = 0;
-                live = 0;
-            }
-            if (!wc->host || !first_entry_t) {
-                if (!first_entry_t) {
-                    delete_dimension_uuid((uuid_t *)sqlite3_column_blob(res, 0));
-                    total_deleted++;
-                    dimension_update_count++;
-                }
-                else {
-                    (void)aclk_upd_dimension_event(
-                        wc,
-                        claim_id,
-                        (uuid_t *)sqlite3_column_blob(res, 0),
-                        (const char *)(const char *)sqlite3_column_text(res, 3),
-                        (const char *)(const char *)sqlite3_column_text(res, 4),
-                        (const char *)(const char *)sqlite3_column_text(res, 2),
-                        first_entry_t,
-                        live ? 0 : last_entry_t,
-                        &send_status);
-
-                    if (!send_status) {
-                        if (last_entry_t)
-                            total_stopped++;
-                        dimension_update_count++;
-                    }
-                }
-            }
-        }
-        total_checked++;
-    }
-    if (update_every) {
-        debug(D_ACLK_SYNC, "Update %s for %u oldest time = %ld", wc->host_guid, update_every, start_time);
-        if (start_time == LONG_MAX)
-            rotate_data.interval_durations[rotate_data.interval_duration_count].retention = 0;
-        else
-            rotate_data.interval_durations[rotate_data.interval_duration_count].retention =
-                rotate_data.rotation_timestamp.tv_sec - start_time;
-        rotate_data.interval_duration_count++;
-    }
-
-    if (dimension_update_count < ACLK_MAX_DIMENSION_CLEANUP && !netdata_exit)
-        log_access("ACLK STA [%s (%s)]: UPDATES %d RETENTION MESSAGE SENT. CHECKED %u DIMENSIONS.  %u DELETED, %u STOPPED COLLECTING",
-                   wc->node_id, wc->hostname ? wc->hostname : "N/A", wc->chart_updates, total_checked, total_deleted, total_stopped);
-    else
-        log_access("ACLK STA [%s (%s)]: UPDATES %d RETENTION MESSAGE NOT SENT. CHECKED %u DIMENSIONS.  %u DELETED, %u STOPPED COLLECTING",
-                   wc->node_id, wc->hostname ? wc->hostname : "N/A", wc->chart_updates, total_checked, total_deleted, total_stopped);
-
-#ifdef NETDATA_INTERNAL_CHECKS
-    info("Retention update for %s (chart updates = %d)", wc->host_guid, wc->chart_updates);
-    for (int i = 0; i < rotate_data.interval_duration_count; ++i)
-        info(
-            "Update for host %s (node %s) for %u Retention = %u",
-            wc->host_guid,
-            wc->node_id,
-            rotate_data.interval_durations[i].update_every,
-            rotate_data.interval_durations[i].retention);
-#endif
-    if (dimension_update_count < ACLK_MAX_DIMENSION_CLEANUP && !netdata_exit)
-        aclk_retention_updated(&rotate_data);
-    freez(rotate_data.node_id);
-    freez(rotate_data.interval_durations);
-
-failed:
-    freez(claim_id);
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize the prepared statement when reading host dimensions");
-    return;
-}
-
-uint32_t sql_get_pending_count(struct aclk_database_worker_config *wc)
-{
-    char sql[ACLK_SYNC_QUERY_SIZE];
-    static __thread sqlite3_stmt *res = NULL;
-
-    snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, "SELECT count(1) FROM aclk_chart_%s ac WHERE ac.date_submitted IS NULL;", wc->uuid_str);
-
-    int rc;
-    uint32_t chart_payload_count = 0;
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, sql, &res);
-        if (rc != SQLITE_OK) {
-            error_report("Failed to prepare statement to count pending messages");
-            return 0;
-        }
-    }
-    while (sqlite3_step(res) == SQLITE_ROW)
-        chart_payload_count = (uint32_t) sqlite3_column_int(res, 0);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement when fetching pending messages, rc = %d", rc);
-
-    return chart_payload_count;
-}
-
-void sql_get_last_chart_sequence(struct aclk_database_worker_config *wc)
-{
-    char sql[ACLK_SYNC_QUERY_SIZE];
-
-    snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, "SELECT ac.sequence_id, ac.date_created FROM aclk_chart_%s ac " \
-        "WHERE ac.date_submitted IS NOT NULL ORDER BY ac.sequence_id DESC LIMIT 1;", wc->uuid_str);
-
-    int rc;
-    sqlite3_stmt *res = NULL;
-    rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
-    if (rc != SQLITE_OK) {
-        error_report("Failed to prepare statement to find last chart sequence id");
-        return;
-    }
-
-    wc->chart_sequence_id = 0;
-    wc->chart_timestamp = 0;
-    while (sqlite3_step(res) == SQLITE_ROW) {
-        wc->chart_sequence_id = (uint64_t)sqlite3_column_int64(res, 0);
-        wc->chart_timestamp = (time_t)sqlite3_column_int64(res, 1);
-    }
-
-    debug(D_ACLK_SYNC, "Node %s reports last sequence_id=%" PRIu64, wc->node_id, wc->chart_sequence_id);
-
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement when fetching chart sequence info, rc = %d", rc);
-
-    return;
-}
-
-void queue_dimension_to_aclk(RRDDIM *rd, time_t last_updated)
-{
-    RRDHOST *host = rd->rrdset->rrdhost;
-    if (likely(rrdhost_flag_check(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS)))
-        return;
-
-    int live = !last_updated;
-
-    if (likely(rd->aclk_live_status == live))
-        return;
-
-    time_t created_at = rd->tiers[0]->query_ops.oldest_time(rd->tiers[0]->db_metric_handle);
-
-    if (unlikely(!created_at && rd->updated))
-       created_at = rd->last_collected_time.tv_sec;
-
-    rd->aclk_live_status = live;
-
-    struct aclk_database_worker_config *wc = rd->rrdset->rrdhost->dbsync_worker;
-    if (unlikely(!wc))
-        return;
-
-    char *claim_id = get_agent_claimid();
-    if (unlikely(!claim_id))
-        return;
-
-    struct chart_dimension_updated dim_payload;
-    memset(&dim_payload, 0, sizeof(dim_payload));
-    dim_payload.node_id = wc->node_id;
-    dim_payload.claim_id = claim_id;
-    dim_payload.name = rd->name;
-    dim_payload.id = rd->id;
-    dim_payload.chart_id = rd->rrdset->id;
-    dim_payload.created_at.tv_sec = created_at;
-    dim_payload.last_timestamp.tv_sec = last_updated;
-
-    size_t size = 0;
-    char *payload = generate_chart_dimension_updated(&size, &dim_payload);
-
-    freez(claim_id);
-    if (unlikely(!payload))
-        return;
-
-    struct aclk_chart_dimension_data *aclk_cd_data = mallocz(sizeof(*aclk_cd_data));
-    uuid_copy(aclk_cd_data->uuid, rd->metric_uuid);
-    aclk_cd_data->payload = payload;
-    aclk_cd_data->payload_size = size;
-    aclk_cd_data->check_payload = 1;
-
-    struct aclk_database_cmd cmd;
-    memset(&cmd, 0, sizeof(cmd));
-
-    cmd.opcode = ACLK_DATABASE_ADD_DIMENSION;
-    cmd.data = aclk_cd_data;
-    int rc = aclk_database_enq_cmd_noblock(wc, &cmd);
-
-    if (unlikely(rc)) {
-        freez(aclk_cd_data->payload);
-        freez(aclk_cd_data);
-        rd->aclk_live_status = !live;
-    }
-    return;
-}
-
-void aclk_send_dimension_update(RRDDIM *rd)
-{
-    char *claim_id = get_agent_claimid();
-    if (unlikely(!claim_id))
-        return;
-
-    time_t first_entry_t = rrddim_first_entry_t(rd);
-    time_t last_entry_t = rrddim_last_entry_t(rd);
-
-    time_t now = now_realtime_sec();
-    int live = ((now - rd->last_collected_time.tv_sec) < (RRDSET_MINIMUM_DIM_LIVE_MULTIPLIER * rd->update_every));
-
-    if (!live || rd->aclk_live_status != live || !first_entry_t) {
-        (void)aclk_upd_dimension_event(
-            rd->rrdset->rrdhost->dbsync_worker,
-            claim_id,
-            &rd->metric_uuid,
-            rd->id,
-            rd->name,
-            rd->rrdset->id,
-            first_entry_t,
-            live ? 0 : last_entry_t,
-            NULL);
-
-        if (!first_entry_t)
-            debug(
-                D_ACLK_SYNC,
-                "%s: Update dimension chart=%s dim=%s live=%d (%ld, %ld)",
-                rd->rrdset->rrdhost->hostname,
-                rd->rrdset->name,
-                rd->name,
-                live,
-                first_entry_t,
-                last_entry_t);
-        else
-            debug(
-                D_ACLK_SYNC,
-                "%s: Update dimension chart=%s dim=%s live=%d (%ld, %ld) collected %ld seconds ago",
-                rd->rrdset->rrdhost->hostname,
-                rd->rrdset->name,
-                rd->name,
-                live,
-                first_entry_t,
-                last_entry_t,
-                now - last_entry_t);
-        rd->aclk_live_status = live;
-    }
-
-    freez(claim_id);
-    return;
-}
-
-#define SQL_SEQ_NULL(result, n)  sqlite3_column_type(result, n) == SQLITE_NULL ? 0 : sqlite3_column_int64(result, n)
-
-struct aclk_chart_sync_stats *aclk_get_chart_sync_stats(RRDHOST *host)
-{
-    struct aclk_chart_sync_stats *aclk_statistics = NULL;
-
-    struct aclk_database_worker_config *wc  = NULL;
-    wc = (struct aclk_database_worker_config *)host->dbsync_worker;
-    if (!wc)
-        return NULL;
-
-    aclk_statistics = callocz(1, sizeof(struct aclk_chart_sync_stats));
-
-    aclk_statistics->updates = wc->chart_updates;
-    aclk_statistics->batch_id = wc->batch_id;
-
-    char host_uuid_fixed[GUID_LEN + 1];
-
-    strncpy(host_uuid_fixed, host->machine_guid, GUID_LEN);
-    host_uuid_fixed[GUID_LEN] = 0;
-
-    host_uuid_fixed[8] = '_';
-    host_uuid_fixed[13] = '_';
-    host_uuid_fixed[18] = '_';
-    host_uuid_fixed[23] = '_';
-
-    sqlite3_stmt *res = NULL;
-    BUFFER *sql = buffer_create(1024);
-    buffer_sprintf(sql, "SELECT min(sequence_id), max(sequence_id), 0 FROM aclk_chart_%s;", host_uuid_fixed);
-    buffer_sprintf(sql, "SELECT min(sequence_id), max(sequence_id), 0 FROM aclk_chart_%s WHERE date_submitted IS NULL;", host_uuid_fixed);
-    buffer_sprintf(sql, "SELECT min(sequence_id), max(sequence_id), 0 FROM aclk_chart_%s WHERE date_submitted IS NOT NULL;", host_uuid_fixed);
-    buffer_sprintf(sql, "SELECT min(sequence_id), max(sequence_id), 0 FROM aclk_chart_%s WHERE date_updated IS NOT NULL;", host_uuid_fixed);
-    buffer_sprintf(sql, "SELECT max(date_created), max(date_submitted), max(date_updated), 0 FROM aclk_chart_%s;", host_uuid_fixed);
-
-    int rc = sqlite3_prepare_v2(db_meta, buffer_tostring(sql), -1, &res, 0);
-    if (rc != SQLITE_OK) {
-        buffer_free(sql);
-        freez(aclk_statistics);
-        return NULL;
-    }
-
-    rc = sqlite3_step(res);
-    if (rc == SQLITE_ROW) {
-        aclk_statistics->min_seqid = SQL_SEQ_NULL(res, 0);
-        aclk_statistics->max_seqid = SQL_SEQ_NULL(res, 1);
-    }
-
-    rc = sqlite3_step(res);
-    if (rc == SQLITE_ROW) {
-        aclk_statistics->min_seqid_pend = SQL_SEQ_NULL(res, 0);
-        aclk_statistics->max_seqid_pend = SQL_SEQ_NULL(res, 1);
-    }
-
-    rc = sqlite3_step(res);
-    if (rc == SQLITE_ROW) {
-        aclk_statistics->min_seqid_sent = SQL_SEQ_NULL(res, 0);
-        aclk_statistics->max_seqid_sent = SQL_SEQ_NULL(res, 1);
-    }
-
-    rc = sqlite3_step(res);
-    if (rc == SQLITE_ROW) {
-        aclk_statistics->min_seqid_ack = SQL_SEQ_NULL(res, 0);
-        aclk_statistics->max_seqid_ack = SQL_SEQ_NULL(res, 1);
-    }
-
-    rc = sqlite3_step(res);
-    if (rc == SQLITE_ROW) {
-        aclk_statistics->min_seqid_ack = SQL_SEQ_NULL(res, 0);
-        aclk_statistics->max_seqid_ack = SQL_SEQ_NULL(res, 1);
-    }
-
-    rc = sqlite3_step(res);
-    if (rc == SQLITE_ROW) {
-        aclk_statistics->max_date_created = (time_t) SQL_SEQ_NULL(res, 0);
-        aclk_statistics->max_date_submitted = (time_t) SQL_SEQ_NULL(res, 1);
-        aclk_statistics->max_date_ack = (time_t) SQL_SEQ_NULL(res, 2);
-    }
-
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize statement when fetching aclk sync statistics, rc = %d", rc);
-
-    buffer_free(sql);
-    return aclk_statistics;
-}
-
-void sql_check_chart_liveness(RRDSET *st) {
-    RRDDIM *rd;
-
-    if (unlikely(st->state->is_ar_chart))
-        return;
-
-    rrdset_rdlock(st);
-
-    if (unlikely(!rrdset_flag_check(st, RRDSET_FLAG_ACLK))) {
-        rrdset_unlock(st);
-        return;
-    }
-
-    if (unlikely(!rrdset_flag_check(st, RRDSET_FLAG_ACLK))) {
-        if (likely(st->dimensions && st->counter_done && !queue_chart_to_aclk(st))) {
-            debug(D_ACLK_SYNC,"Check chart liveness [%s] submit chart definition", st->name);
-            rrdset_flag_set(st, RRDSET_FLAG_ACLK);
-        }
-    }
-    else
-        debug(D_ACLK_SYNC,"Check chart liveness [%s] chart definition already submitted", st->name);
-    time_t mark = now_realtime_sec();
-
-    debug(D_ACLK_SYNC,"Check chart liveness [%s] scanning dimensions", st->name);
-    rrddim_foreach_read(rd, st) {
-        if (!rrddim_flag_check(rd, RRDDIM_FLAG_HIDDEN))
-            queue_dimension_to_aclk(rd, calc_dimension_liveness(rd, mark));
-    }
-    rrdset_unlock(st);
-}
-
-// ST is read locked
-int queue_chart_to_aclk(RRDSET *st)
-{
-    RRDHOST *host = st->rrdhost;
-
-    if (likely(rrdhost_flag_check(host, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS)))
-        return 0;
-
-    return sql_queue_chart_payload((struct aclk_database_worker_config *) st->rrdhost->dbsync_worker,
-                                       st, ACLK_DATABASE_ADD_CHART);
-}
-
-#endif //ENABLE_ACLK
diff --git a/database/sqlite/sqlite_aclk_chart.h b/database/sqlite/sqlite_aclk_chart.h
deleted file mode 100644
index 84325bf6c..000000000
--- a/database/sqlite/sqlite_aclk_chart.h
+++ /dev/null
@@ -1,71 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#ifndef NETDATA_SQLITE_ACLK_CHART_H
-#define NETDATA_SQLITE_ACLK_CHART_H
-
-
-typedef enum payload_type {
-    ACLK_PAYLOAD_CHART,
-    ACLK_PAYLOAD_DIMENSION,
-    ACLK_PAYLOAD_DIMENSION_ROTATED
-} ACLK_PAYLOAD_TYPE;
-
-extern sqlite3 *db_meta;
-
-#ifndef RRDSET_MINIMUM_DIM_LIVE_MULTIPLIER
-#define RRDSET_MINIMUM_DIM_LIVE_MULTIPLIER   (3)
-#endif
-
-#ifndef RRDSET_MINIMUM_DIM_OFFLINE_MULTIPLIER
-#define RRDSET_MINIMUM_DIM_OFFLINE_MULTIPLIER (30)
-#endif
-
-#ifndef ACLK_MAX_DIMENSION_CLEANUP
-#define ACLK_MAX_DIMENSION_CLEANUP (500)
-#endif
-
-struct aclk_chart_dimension_data {
-    uuid_t uuid;
-    char *payload;
-    size_t payload_size;
-    uint8_t check_payload;
-};
-
-struct aclk_chart_sync_stats {
-    int        updates;
-    uint64_t   batch_id;
-    uint64_t   min_seqid;
-    uint64_t   max_seqid;
-    uint64_t   min_seqid_pend;
-    uint64_t   max_seqid_pend;
-    uint64_t   min_seqid_sent;
-    uint64_t   max_seqid_sent;
-    uint64_t   min_seqid_ack;
-    uint64_t   max_seqid_ack;
-    time_t     max_date_created;
-    time_t     max_date_submitted;
-    time_t     max_date_ack;
-};
-
-extern int queue_chart_to_aclk(RRDSET *st);
-extern void queue_dimension_to_aclk(RRDDIM *rd, time_t last_updated);
-extern void sql_create_aclk_table(RRDHOST *host, uuid_t *host_uuid, uuid_t *node_id);
-int aclk_add_chart_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-int aclk_add_dimension_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-int aclk_send_chart_config(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void aclk_ack_chart_sequence_id(char *node_id, uint64_t last_sequence_id);
-void aclk_get_chart_config(char **hash_id_list);
-void aclk_send_chart_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void aclk_start_streaming(char *node_id, uint64_t seq_id, time_t created_at, uint64_t batch_id);
-void sql_chart_deduplicate(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void sql_check_rotation_state(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void sql_get_last_chart_sequence(struct aclk_database_worker_config *wc);
-void aclk_receive_chart_reset(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void aclk_receive_chart_ack(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void aclk_process_dimension_deletion(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-uint32_t sql_get_pending_count(struct aclk_database_worker_config *wc);
-void aclk_send_dimension_update(RRDDIM *rd);
-struct aclk_chart_sync_stats *aclk_get_chart_sync_stats(RRDHOST *host);
-void sql_check_chart_liveness(RRDSET *st);
-void aclk_update_retention(struct aclk_database_worker_config *wc);
-#endif //NETDATA_SQLITE_ACLK_CHART_H
diff --git a/database/sqlite/sqlite_aclk_node.c b/database/sqlite/sqlite_aclk_node.c
index 3d11f83aa..afe774997 100644
--- a/database/sqlite/sqlite_aclk_node.c
+++ b/database/sqlite/sqlite_aclk_node.c
@@ -3,27 +3,25 @@
 #include "sqlite_functions.h"
 #include "sqlite_aclk_node.h"
 
-#ifdef ENABLE_ACLK
-#include "../../aclk/aclk_charts_api.h"
-#endif
+#include "../../aclk/aclk_contexts_api.h"
+#include "../../aclk/aclk_capas.h"
 
 #ifdef ENABLE_ACLK
 DICTIONARY *collectors_from_charts(RRDHOST *host, DICTIONARY *dict) {
     RRDSET *st;
     char name[500];
 
-    rrdhost_rdlock(host);
     rrdset_foreach_read(st, host) {
         if (rrdset_is_available_for_viewers(st)) {
             struct collector_info col = {
-                    .plugin = st->plugin_name ? st->plugin_name : "",
-                    .module = st->module_name ? st->module_name : ""
+                    .plugin = rrdset_plugin_name(st),
+                    .module = rrdset_module_name(st)
             };
             snprintfz(name, 499, "%s:%s", col.plugin, col.module);
             dictionary_set(dict, name, &col, sizeof(struct collector_info));
         }
     }
-    rrdhost_unlock(host);
+    rrdset_foreach_done(st);
 
     return dict;
 }
@@ -36,7 +34,7 @@ void sql_build_node_collectors(struct aclk_database_worker_config *wc)
         return;
 
     struct update_node_collectors upd_node_collectors;
-    DICTIONARY *dict = dictionary_create(DICTIONARY_FLAG_SINGLE_THREADED);
+    DICTIONARY *dict = dictionary_create(DICT_OPTION_SINGLE_THREADED);
 
     upd_node_collectors.node_id = wc->node_id;
     upd_node_collectors.claim_id = get_agent_claimid();
@@ -47,7 +45,7 @@ void sql_build_node_collectors(struct aclk_database_worker_config *wc)
     dictionary_destroy(dict);
     freez(upd_node_collectors.claim_id);
 
-    log_access("ACLK RES [%s (%s)]: NODE COLLECTORS SENT", wc->node_id, wc->host->hostname);
+    log_access("ACLK RES [%s (%s)]: NODE COLLECTORS SENT", wc->node_id, rrdhost_hostname(wc->host));
 #else
     UNUSED(wc);
 #endif
@@ -74,14 +72,7 @@ void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_dat
     node_info.ml_info.ml_capable = ml_capable(localhost);
     node_info.ml_info.ml_enabled = ml_enabled(wc->host);
 
-    struct capability instance_caps[] = {
-        { .name = "proto", .version = 1,                     .enabled = 1 },
-        { .name = "ml",    .version = ml_capable(localhost), .enabled = ml_enabled(wc->host) },
-        { .name = "mc",    .version = enable_metric_correlations ? metric_correlations_version : 0, .enabled = enable_metric_correlations },
-        { .name = "ctx",   .version = 1,                     .enabled = rrdcontext_enabled},
-        { .name = NULL,    .version = 0,                     .enabled = 0 }
-    };
-    node_info.node_instance_capabilities = instance_caps;
+    node_info.node_instance_capabilities = aclk_get_node_instance_capas(wc->host);
 
     now_realtime_timeval(&node_info.updated_at);
 
@@ -89,13 +80,12 @@ void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_dat
     char *host_version = NULL;
     if (host != localhost) {
         netdata_mutex_lock(&host->receiver_lock);
-        host_version =
-            strdupz(host->receiver && host->receiver->program_version ? host->receiver->program_version : "unknown");
+        host_version = strdupz(host->receiver && host->receiver->program_version ? host->receiver->program_version : "unknown");
         netdata_mutex_unlock(&host->receiver_lock);
     }
 
-    node_info.data.name = host->hostname;
-    node_info.data.os = (char *) host->os;
+    node_info.data.name = rrdhost_hostname(host);
+    node_info.data.os = rrdhost_os(host);
     node_info.data.os_name = host->system_info->host_os_name;
     node_info.data.os_version = host->system_info->host_os_version;
     node_info.data.kernel_name = host->system_info->kernel_name;
@@ -106,8 +96,8 @@ void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_dat
     node_info.data.memory = host->system_info->host_ram_total ? host->system_info->host_ram_total : "0";
     node_info.data.disk_space = host->system_info->host_disk_space ? host->system_info->host_disk_space : "0";
     node_info.data.version = host_version ? host_version : VERSION;
-    node_info.data.release_channel = (char *) get_release_channel();
-    node_info.data.timezone = (char *) host->abbrev_timezone;
+    node_info.data.release_channel = get_release_channel();
+    node_info.data.timezone = rrdhost_abbrev_timezone(host);
     node_info.data.virtualization_type = host->system_info->virtualization ? host->system_info->virtualization : "unknown";
     node_info.data.container_type = host->system_info->container ? host->system_info->container : "unknown";
     node_info.data.custom_info = config_get(CONFIG_SECTION_WEB, "custom dashboard_info.js", "");
@@ -123,13 +113,14 @@ void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_dat
     node_info.data.ml_info.ml_capable = host->system_info->ml_capable;
     node_info.data.ml_info.ml_enabled = host->system_info->ml_enabled;
 
-    node_info.data.host_labels_ptr = host->host_labels;
+    node_info.data.host_labels_ptr = host->rrdlabels;
 
     aclk_update_node_info(&node_info);
-    log_access("ACLK RES [%s (%s)]: NODE INFO SENT for guid [%s] (%s)", wc->node_id, wc->host->hostname, wc->host_guid, wc->host == localhost ? "parent" : "child");
+    log_access("ACLK RES [%s (%s)]: NODE INFO SENT for guid [%s] (%s)", wc->node_id, rrdhost_hostname(wc->host), wc->host_guid, wc->host == localhost ? "parent" : "child");
 
     rrd_unlock();
     freez(node_info.claim_id);
+    freez(node_info.node_instance_capabilities);
     freez(host_version);
 
     wc->node_collectors_send = now_realtime_sec();
diff --git a/database/sqlite/sqlite_context.c b/database/sqlite/sqlite_context.c
index 901ab0031..9c7a61c6e 100644
--- a/database/sqlite/sqlite_context.c
+++ b/database/sqlite/sqlite_context.c
@@ -21,7 +21,6 @@ const char *database_context_cleanup[] = {
 };
 
 sqlite3 *db_context_meta = NULL;
-
 /*
  * Initialize the SQLite database
  * Return 0 on success
@@ -125,22 +124,24 @@ void sql_close_context_database(void)
 // Fetching data
 //
 #define CTX_GET_CHART_LIST  "SELECT c.chart_id, c.type||'.'||c.id, c.name, c.context, c.title, c.unit, c.priority, " \
-        "c.update_every, c.chart_type, c.family FROM meta.chart c WHERE c.host_id = @host_id; "
+        "c.update_every, c.chart_type, c.family FROM meta.chart c WHERE c.host_id = @host_id and c.chart_id is not null; "
 
 void ctx_get_chart_list(uuid_t *host_uuid, void (*dict_cb)(SQL_CHART_DATA *, void *), void *data)
 {
     int rc;
-    sqlite3_stmt *res = NULL;
+    static __thread sqlite3_stmt *res = NULL;
 
     if (unlikely(!host_uuid)) {
        internal_error(true, "Requesting context chart list without host_id");
        return;
     }
 
-    rc = sqlite3_prepare_v2(db_context_meta, CTX_GET_CHART_LIST, -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to fetch chart list");
-        return;
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_context_meta, CTX_GET_CHART_LIST, &res);
+        if (rc != SQLITE_OK) {
+            error_report("Failed to prepare statement to fetch chart list");
+            return;
+        }
     }
 
     rc = sqlite3_bind_blob(res, 1, host_uuid, sizeof(*host_uuid), SQLITE_STATIC);
@@ -150,7 +151,7 @@ void ctx_get_chart_list(uuid_t *host_uuid, void (*dict_cb)(SQL_CHART_DATA *, voi
     }
 
     SQL_CHART_DATA chart_data = { 0 };
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         uuid_copy(chart_data.chart_id, *((uuid_t *)sqlite3_column_blob(res, 0)));
         chart_data.id = (char *) sqlite3_column_text(res, 1);
         chart_data.name = (char *) sqlite3_column_text(res, 2);
@@ -165,22 +166,25 @@ void ctx_get_chart_list(uuid_t *host_uuid, void (*dict_cb)(SQL_CHART_DATA *, voi
     }
 
 skip_load:
-    rc = sqlite3_finalize(res);
+    rc = sqlite3_reset(res);
     if (rc != SQLITE_OK)
-        error_report("Failed to finalize statement that fetches chart label data, rc = %d", rc);
+        error_report("Failed to reset statement that fetches chart label data, rc = %d", rc);
 }
 
 // Dimension list
-#define CTX_GET_DIMENSION_LIST  "SELECT d.dim_id, d.id, d.name FROM meta.dimension d WHERE d.chart_id = @id;"
+#define CTX_GET_DIMENSION_LIST  "SELECT d.dim_id, d.id, d.name, CASE WHEN INSTR(d.options,\"hidden\") > 0 THEN 1 ELSE 0 END " \
+        "FROM meta.dimension d WHERE d.chart_id = @id and d.dim_id is not null ORDER BY d.rowid ASC;"
 void ctx_get_dimension_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_DIMENSION_DATA *, void *), void *data)
 {
     int rc;
-    sqlite3_stmt *res = NULL;
-
-    rc = sqlite3_prepare_v2(db_context_meta, CTX_GET_DIMENSION_LIST, -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to fetch chart dimension data");
-        return;
+    static __thread sqlite3_stmt *res = NULL;
+
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_context_meta, CTX_GET_DIMENSION_LIST, &res);
+        if (rc != SQLITE_OK) {
+            error_report("Failed to prepare statement to fetch chart dimension data");
+            return;
+        }
     }
 
     rc = sqlite3_bind_blob(res, 1, chart_uuid, sizeof(*chart_uuid), SQLITE_STATIC);
@@ -191,17 +195,18 @@ void ctx_get_dimension_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_DIMENSION_DA
 
     SQL_DIMENSION_DATA dimension_data;
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         uuid_copy(dimension_data.dim_id, *((uuid_t *)sqlite3_column_blob(res, 0)));
         dimension_data.id = (char *) sqlite3_column_text(res, 1);
         dimension_data.name = (char *) sqlite3_column_text(res, 2);
+        dimension_data.hidden = sqlite3_column_int(res, 3);
         dict_cb(&dimension_data, data);
     }
 
 failed:
-    rc = sqlite3_finalize(res);
+    rc = sqlite3_reset(res);
     if (rc != SQLITE_OK)
-        error_report("Failed to finalize statement that fetches the chart dimension list, rc = %d", rc);
+        error_report("Failed to reset statement that fetches the chart dimension list, rc = %d", rc);
 }
 
 // LABEL LIST
@@ -209,12 +214,14 @@ failed:
 void ctx_get_label_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_CLABEL_DATA *, void *), void *data)
 {
     int rc;
-    sqlite3_stmt *res = NULL;
-
-    rc = sqlite3_prepare_v2(db_context_meta, CTX_GET_LABEL_LIST, -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to fetch chart lanbels");
-        return;
+    static __thread sqlite3_stmt *res = NULL;
+
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_context_meta, CTX_GET_LABEL_LIST, &res);
+        if (rc != SQLITE_OK) {
+            error_report("Failed to prepare statement to fetch chart labels");
+            return;
+        }
     }
 
     rc = sqlite3_bind_blob(res, 1, chart_uuid, sizeof(*chart_uuid), SQLITE_STATIC);
@@ -225,7 +232,7 @@ void ctx_get_label_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_CLABEL_DATA *, v
 
     SQL_CLABEL_DATA label_data;
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         label_data.label_key = (char *) sqlite3_column_text(res, 0);
         label_data.label_value = (char *) sqlite3_column_text(res, 1);
         label_data.label_source = sqlite3_column_int(res, 2);
@@ -233,9 +240,9 @@ void ctx_get_label_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_CLABEL_DATA *, v
     }
 
 failed:
-    rc = sqlite3_finalize(res);
+    rc = sqlite3_reset(res);
     if (rc != SQLITE_OK)
-        error_report("Failed to finalize statement that fetches chart label data, rc = %d", rc);
+        error_report("Failed to reset statement that fetches chart label data, rc = %d", rc);
 
     return;
 }
@@ -250,12 +257,14 @@ void ctx_get_context_list(uuid_t *host_uuid, void (*dict_cb)(VERSIONED_CONTEXT_D
         return;
 
     int rc;
-    sqlite3_stmt *res = NULL;
-
-    rc = sqlite3_prepare_v2(db_context_meta, CTX_GET_CONTEXT_LIST, -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to fetch stored context list");
-        return;
+    static __thread sqlite3_stmt *res = NULL;
+
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_context_meta, CTX_GET_CONTEXT_LIST, &res);
+        if (rc != SQLITE_OK) {
+            error_report("Failed to prepare statement to fetch stored context list");
+            return;
+        }
     }
 
     VERSIONED_CONTEXT_DATA context_data = {0};
@@ -267,7 +276,7 @@ void ctx_get_context_list(uuid_t *host_uuid, void (*dict_cb)(VERSIONED_CONTEXT_D
         goto failed;
     }
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         context_data.id = (char *) sqlite3_column_text(res, 0);
         context_data.version = sqlite3_column_int64(res, 1);
         context_data.title = (char *) sqlite3_column_text(res, 2);
@@ -282,9 +291,9 @@ void ctx_get_context_list(uuid_t *host_uuid, void (*dict_cb)(VERSIONED_CONTEXT_D
     }
 
 failed:
-    rc = sqlite3_finalize(res);
+    rc = sqlite3_reset(res);
     if (rc != SQLITE_OK)
-        error_report("Failed to finalize statement that fetches stored context versioned data, rc = %d", rc);
+        error_report("Failed to reset statement that fetches stored context versioned data, rc = %d", rc);
 }
 
 
@@ -437,6 +446,13 @@ skip_delete:
     return (rc_stored != SQLITE_DONE);
 }
 
+int sql_context_cache_stats(int op)
+{
+    int count, dummy;
+    sqlite3_db_status(db_context_meta, op, &count, &dummy, 0);
+    return count;
+}
+
 //
 // TESTING FUNCTIONS
 //
diff --git a/database/sqlite/sqlite_context.h b/database/sqlite/sqlite_context.h
index 12937fffd..2e52b9bf8 100644
--- a/database/sqlite/sqlite_context.h
+++ b/database/sqlite/sqlite_context.h
@@ -6,6 +6,7 @@
 #include "daemon/common.h"
 #include "sqlite3.h"
 
+int sql_context_cache_stats(int op);
 typedef struct ctx_chart {
     uuid_t chart_id;
     const char *id;
@@ -23,6 +24,7 @@ typedef struct ctx_dimension {
     uuid_t dim_id;
     char *id;
     char *name;
+    bool hidden;
 } SQL_DIMENSION_DATA;
 
 typedef struct ctx_label {
@@ -50,19 +52,19 @@ typedef struct versioned_context_data {
 
 } VERSIONED_CONTEXT_DATA;
 
-extern void ctx_get_context_list(uuid_t *host_uuid, void (*dict_cb)(VERSIONED_CONTEXT_DATA *, void *), void *data);
+void ctx_get_context_list(uuid_t *host_uuid, void (*dict_cb)(VERSIONED_CONTEXT_DATA *, void *), void *data);
 
-extern void ctx_get_chart_list(uuid_t *host_uuid, void (*dict_cb)(SQL_CHART_DATA *, void *), void *data);
-extern void ctx_get_label_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_CLABEL_DATA *, void *), void *data);
-extern void ctx_get_dimension_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_DIMENSION_DATA *, void *), void *data);
+void ctx_get_chart_list(uuid_t *host_uuid, void (*dict_cb)(SQL_CHART_DATA *, void *), void *data);
+void ctx_get_label_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_CLABEL_DATA *, void *), void *data);
+void ctx_get_dimension_list(uuid_t *chart_uuid, void (*dict_cb)(SQL_DIMENSION_DATA *, void *), void *data);
 
-extern int ctx_store_context(uuid_t *host_uuid, VERSIONED_CONTEXT_DATA *context_data);
+int ctx_store_context(uuid_t *host_uuid, VERSIONED_CONTEXT_DATA *context_data);
 
 #define ctx_update_context(host_uuid, context_data)    ctx_store_context(host_uuid, context_data)
 
-extern int ctx_delete_context(uuid_t *host_id, VERSIONED_CONTEXT_DATA *context_data);
+int ctx_delete_context(uuid_t *host_id, VERSIONED_CONTEXT_DATA *context_data);
 
-extern int sql_init_context_database(int memory);
-extern void sql_close_context_database(void);
-extern int ctx_unittest(void);
+int sql_init_context_database(int memory);
+void sql_close_context_database(void);
+int ctx_unittest(void);
 #endif //NETDATA_SQLITE_CONTEXT_H
diff --git a/database/sqlite/sqlite_db_migration.c b/database/sqlite/sqlite_db_migration.c
index bd4743364..8b1d01594 100644
--- a/database/sqlite/sqlite_db_migration.c
+++ b/database/sqlite/sqlite_db_migration.c
@@ -21,7 +21,7 @@ static int table_exists_in_database(const char *table)
 
     snprintf(sql, 127, "select 1 from sqlite_schema where type = 'table' and name = '%s';", table);
 
-    int rc = sqlite3_exec(db_meta, sql, return_int_cb, (void *) &exists, &err_msg);
+    int rc = sqlite3_exec_monitored(db_meta, sql, return_int_cb, (void *) &exists, &err_msg);
     if (rc != SQLITE_OK) {
         info("Error checking table existence; %s", err_msg);
         sqlite3_free(err_msg);
@@ -39,7 +39,7 @@ static int column_exists_in_table(const char *table, const char *column)
 
     snprintf(sql, 127, "SELECT 1 FROM pragma_table_info('%s') where name = '%s';", table, column);
 
-    int rc = sqlite3_exec(db_meta, sql, return_int_cb, (void *) &exists, &err_msg);
+    int rc = sqlite3_exec_monitored(db_meta, sql, return_int_cb, (void *) &exists, &err_msg);
     if (rc != SQLITE_OK) {
         info("Error checking column existence; %s", err_msg);
         sqlite3_free(err_msg);
@@ -64,6 +64,22 @@ const char *database_migrate_v2_v3[] = {
     NULL
 };
 
+const char *database_migrate_v4_v5[] = {
+    "DROP TABLE IF EXISTS chart_active;",
+    "DROP TABLE IF EXISTS dimension_active;",
+    "DROP TABLE IF EXISTS chart_hash;",
+    "DROP TABLE IF EXISTS chart_hash_map;",
+    "DROP VIEW IF EXISTS v_chart_hash;",
+    NULL
+};
+
+const char *database_migrate_v5_v6[] = {
+    "DROP TRIGGER IF EXISTS tr_dim_del;",
+    "DROP TABLE IF EXISTS dimension_delete;",
+    NULL
+};
+
+
 static int do_migration_v1_v2(sqlite3 *database, const char *name)
 {
     UNUSED(name);
@@ -100,11 +116,11 @@ static int do_migration_v3_v4(sqlite3 *database, const char *name)
         return 1;
     }
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
          char *table = strdupz((char *) sqlite3_column_text(res, 0));
          if (!column_exists_in_table(table, "chart_context")) {
              snprintfz(sql, 255, "ALTER TABLE %s ADD chart_context text", table);
-             sqlite3_exec(database, sql, 0, 0, NULL);
+             sqlite3_exec_monitored(database, sql, 0, 0, NULL);
          }
          freez(table);
     }
@@ -116,6 +132,57 @@ static int do_migration_v3_v4(sqlite3 *database, const char *name)
     return 0;
 }
 
+static int do_migration_v4_v5(sqlite3 *database, const char *name)
+{
+    UNUSED(name);
+    info("Running \"%s\" database migration", name);
+
+    return init_database_batch(database, DB_CHECK_NONE, 0, &database_migrate_v4_v5[0]);
+}
+
+static int do_migration_v5_v6(sqlite3 *database, const char *name)
+{
+    UNUSED(name);
+    info("Running \"%s\" database migration", name);
+
+    return init_database_batch(database, DB_CHECK_NONE, 0, &database_migrate_v5_v6[0]);
+}
+
+static int do_migration_v6_v7(sqlite3 *database, const char *name)
+{
+    UNUSED(name);
+    info("Running \"%s\" database migration", name);
+
+    char sql[256];
+
+    int rc;
+    sqlite3_stmt *res = NULL;
+    snprintfz(sql, 255, "SELECT name FROM sqlite_schema WHERE type ='table' AND name LIKE 'aclk_alert_%%';");
+    rc = sqlite3_prepare_v2(database, sql, -1, &res, 0);
+    if (rc != SQLITE_OK) {
+        error_report("Failed to prepare statement to alter aclk_alert tables");
+        return 1;
+    }
+
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
+         char *table = strdupz((char *) sqlite3_column_text(res, 0));
+         if (!column_exists_in_table(table, "filtered_alert_unique_id")) {
+             snprintfz(sql, 255, "ALTER TABLE %s ADD filtered_alert_unique_id", table);
+             sqlite3_exec_monitored(database, sql, 0, 0, NULL);
+             snprintfz(sql, 255, "UPDATE %s SET filtered_alert_unique_id = alert_unique_id", table);
+             sqlite3_exec_monitored(database, sql, 0, 0, NULL);
+         }
+         freez(table);
+    }
+
+    rc = sqlite3_finalize(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to finalize statement when altering aclk_alert tables, rc = %d", rc);
+
+    return 0;
+}
+
+
 static int do_migration_noop(sqlite3 *database, const char *name)
 {
     UNUSED(database);
@@ -135,7 +202,7 @@ static int migrate_database(sqlite3 *database, int target_version, char *db_name
     int user_version = 0;
     char *err_msg = NULL;
 
-    int rc = sqlite3_exec(database, "PRAGMA user_version;", return_int_cb, (void *) &user_version, &err_msg);
+    int rc = sqlite3_exec_monitored(database, "PRAGMA user_version;", return_int_cb, (void *) &user_version, &err_msg);
     if (rc != SQLITE_OK) {
         info("Error checking the %s database version; %s", db_name, err_msg);
         sqlite3_free(err_msg);
@@ -163,6 +230,9 @@ DATABASE_FUNC_MIGRATION_LIST migration_action[] = {
     {.name = "v1 to v2",  .func = do_migration_v1_v2},
     {.name = "v2 to v3",  .func = do_migration_v2_v3},
     {.name = "v3 to v4",  .func = do_migration_v3_v4},
+    {.name = "v4 to v5",  .func = do_migration_v4_v5},
+    {.name = "v5 to v6",  .func = do_migration_v5_v6},
+    {.name = "v6 to v7",  .func = do_migration_v6_v7},
     // the terminator of this array
     {.name = NULL, .func = NULL}
 };
diff --git a/database/sqlite/sqlite_functions.c b/database/sqlite/sqlite_functions.c
index f46450afa..eeb3c3822 100644
--- a/database/sqlite/sqlite_functions.c
+++ b/database/sqlite/sqlite_functions.c
@@ -3,7 +3,7 @@
 #include "sqlite_functions.h"
 #include "sqlite_db_migration.h"
 
-#define DB_METADATA_VERSION 4
+#define DB_METADATA_VERSION 7
 
 const char *database_config[] = {
     "CREATE TABLE IF NOT EXISTS host(host_id BLOB PRIMARY KEY, hostname TEXT NOT NULL, "
@@ -21,14 +21,10 @@ const char *database_config[] = {
     "CREATE TABLE IF NOT EXISTS dimension(dim_id blob PRIMARY KEY, chart_id blob, id text, name text, "
     "multiplier int, divisor int , algorithm int, options text);",
 
-    "DROP TABLE IF EXISTS chart_active;",
-    "DROP TABLE IF EXISTS dimension_active;",
-
-    "CREATE TABLE IF NOT EXISTS chart_active(chart_id blob PRIMARY KEY, date_created int);",
-    "CREATE TABLE IF NOT EXISTS dimension_active(dim_id blob primary key, date_created int);",
     "CREATE TABLE IF NOT EXISTS metadata_migration(filename text, file_size, date_created int);",
     "CREATE INDEX IF NOT EXISTS ind_d1 on dimension (chart_id, id, name);",
     "CREATE INDEX IF NOT EXISTS ind_c1 on chart (host_id, id, type, name);",
+    "CREATE INDEX IF NOT EXISTS ind_c2 on chart (host_id, context);",
     "CREATE TABLE IF NOT EXISTS chart_label(chart_id blob, source_type int, label_key text, "
     "label_value text, date_created int, PRIMARY KEY (chart_id, label_key));",
     "CREATE TABLE IF NOT EXISTS node_instance (host_id blob PRIMARY KEY, claim_id, node_id, date_created);",
@@ -45,39 +41,20 @@ const char *database_config[] = {
     "CREATE TABLE IF NOT EXISTS host_label(host_id blob, source_type int, label_key text NOT NULL, "
     "label_value text NOT NULL, date_created INT, PRIMARY KEY (host_id, label_key));",
 
-    "CREATE TABLE IF NOT EXISTS chart_hash_map(chart_id blob , hash_id blob, UNIQUE (chart_id, hash_id));",
-
-    "CREATE TABLE IF NOT EXISTS chart_hash(hash_id blob PRIMARY KEY,type text, id text, name text, "
-    "family text, context text, title text, unit text, plugin text, "
-    "module text, priority integer, chart_type, last_used);",
-
-    "CREATE VIEW IF NOT EXISTS v_chart_hash as SELECT ch.*, chm.chart_id FROM chart_hash ch, chart_hash_map chm "
-    "WHERE ch.hash_id = chm.hash_id;",
-
     "CREATE TRIGGER IF NOT EXISTS ins_host AFTER INSERT ON host BEGIN INSERT INTO node_instance (host_id, date_created)"
       " SELECT new.host_id, unixepoch() WHERE new.host_id NOT IN (SELECT host_id FROM node_instance); END;",
 
-    "CREATE TRIGGER IF NOT EXISTS tr_v_chart_hash INSTEAD OF INSERT on v_chart_hash BEGIN "
-    "INSERT INTO chart_hash (hash_id, type, id, name, family, context, title, unit, plugin, "
-    "module, priority, chart_type, last_used) "
-    "values (new.hash_id, new.type, new.id, new.name, new.family, new.context, new.title, new.unit, new.plugin, "
-    "new.module, new.priority, new.chart_type, unixepoch()) "
-    "ON CONFLICT (hash_id) DO UPDATE SET last_used = unixepoch(); "
-    "INSERT INTO chart_hash_map (chart_id, hash_id) values (new.chart_id, new.hash_id) "
-    "on conflict (chart_id, hash_id) do nothing; END; ",
-
     NULL
 };
 
 const char *database_cleanup[] = {
-    "delete from chart where chart_id not in (select chart_id from dimension);",
-    "delete from host where host_id not in (select host_id from chart);",
-    "delete from chart_label where chart_id not in (select chart_id from chart);",
-    "DELETE FROM chart_hash_map WHERE chart_id NOT IN (SELECT chart_id FROM chart);",
-    "DELETE FROM chart_hash WHERE hash_id NOT IN (SELECT hash_id FROM chart_hash_map);",
+    "DELETE FROM chart WHERE chart_id NOT IN (SELECT chart_id FROM dimension);",
+    "DELETE FROM host WHERE host_id NOT IN (SELECT host_id FROM chart);",
+    "DELETE FROM chart_label WHERE chart_id NOT IN (SELECT chart_id FROM chart);",
     "DELETE FROM node_instance WHERE host_id NOT IN (SELECT host_id FROM host);",
     "DELETE FROM host_info WHERE host_id NOT IN (SELECT host_id FROM host);",
     "DELETE FROM host_label WHERE host_id NOT IN (SELECT host_id FROM host);",
+    "DROP TRIGGER IF EXISTS tr_dim_del;",
     NULL
 };
 
@@ -86,13 +63,49 @@ sqlite3 *db_meta = NULL;
 #define MAX_PREPARED_STATEMENTS (32)
 pthread_key_t key_pool[MAX_PREPARED_STATEMENTS];
 
-static uv_mutex_t sqlite_transaction_lock;
+SQLITE_API int sqlite3_exec_monitored(
+    sqlite3 *db,                               /* An open database */
+    const char *sql,                           /* SQL to be evaluated */
+    int (*callback)(void*,int,char**,char**),  /* Callback function */
+    void *data,                                /* 1st argument to callback */
+    char **errmsg                              /* Error msg written here */
+) {
+    int rc = sqlite3_exec(db, sql, callback, data, errmsg);
+    global_statistics_sqlite3_query_completed(rc == SQLITE_OK, rc == SQLITE_BUSY, rc == SQLITE_LOCKED);
+    return rc;
+}
+
+SQLITE_API int sqlite3_step_monitored(sqlite3_stmt *stmt) {
+    int rc;
+    int cnt = 0;
+
+    while (cnt++ < SQL_MAX_RETRY) {
+        rc = sqlite3_step(stmt);
+        switch (rc) {
+            case SQLITE_DONE:
+                global_statistics_sqlite3_query_completed(1, 0, 0);
+                break;
+            case SQLITE_ROW:
+                global_statistics_sqlite3_row_completed();
+                break;
+            case SQLITE_BUSY:
+            case SQLITE_LOCKED:
+                global_statistics_sqlite3_query_completed(rc == SQLITE_DONE, rc == SQLITE_BUSY, rc == SQLITE_LOCKED);
+                usleep(SQLITE_INSERT_DELAY * USEC_PER_MS);
+                continue;
+            default:
+                break;
+        }
+        break;
+    }
+    return rc;
+}
 
 int execute_insert(sqlite3_stmt *res)
 {
     int rc;
     int cnt = 0;
-    while ((rc = sqlite3_step(res)) != SQLITE_DONE && ++cnt < SQL_MAX_RETRY && likely(!netdata_exit)) {
+    while ((rc = sqlite3_step_monitored(res)) != SQLITE_DONE && ++cnt < SQL_MAX_RETRY && likely(!netdata_exit)) {
         if (likely(rc == SQLITE_BUSY || rc == SQLITE_LOCKED)) {
             usleep(SQLITE_INSERT_DELAY * USEC_PER_MS);
             error_report("Failed to insert/update, rc = %d -- attempt %d", rc, cnt);
@@ -134,14 +147,14 @@ static void add_stmt_to_list(sqlite3_stmt *res)
 static void release_statement(void *statement)
 {
     int rc;
-#ifdef NETDATA_INTERNAL_CHECKS
+#ifdef NETDATA_DEV_MODE
     info("Thread %d: Cleaning prepared statement on %p", gettid(), statement);
 #endif
     if (unlikely(rc = sqlite3_finalize((sqlite3_stmt *) statement) != SQLITE_OK))
         error_report("Failed to finalize statement, rc = %d", rc);
 }
 
-int prepare_statement(sqlite3 *database, char *query, sqlite3_stmt **statement)
+int prepare_statement(sqlite3 *database, const char *query, sqlite3_stmt **statement)
 {
     static __thread uint32_t keys_used = 0;
 
@@ -155,7 +168,7 @@ int prepare_statement(sqlite3 *database, char *query, sqlite3_stmt **statement)
     if (likely(rc == SQLITE_OK)) {
         if (likely(key)) {
             ret = pthread_setspecific(*key, *statement);
-#ifdef NETDATA_INTERNAL_CHECKS
+#ifdef NETDATA_DEV_MODE
             info("Thread %d: Using key %u on statement %p", gettid(), keys_used, *statement);
 #endif
         }
@@ -165,88 +178,6 @@ int prepare_statement(sqlite3 *database, char *query, sqlite3_stmt **statement)
     return rc;
 }
 
-/*
- * Store a chart or dimension UUID in  chart_active or dimension_active
- * The statement that will be prepared determines that
- */
-
-static int store_active_uuid_object(sqlite3_stmt **res, char *statement, uuid_t *uuid)
-{
-    int rc;
-
-    // Check if we should need to prepare the statement
-    if (!*res) {
-        rc = prepare_statement(db_meta, statement, res);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement to store active object, rc = %d", rc);
-            return rc;
-        }
-    }
-
-    rc = sqlite3_bind_blob(*res, 1, uuid, sizeof(*uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to bind input parameter to store active object, rc = %d", rc);
-    else
-        rc = execute_insert(*res);
-    return rc;
-}
-
-/*
- * Marks a chart with UUID as active
- * Input: UUID
- */
-void store_active_chart(uuid_t *chart_uuid)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("Database has not been initialized");
-        return;
-    }
-
-    if (unlikely(!chart_uuid))
-        return;
-
-    rc = store_active_uuid_object(&res, SQL_STORE_ACTIVE_CHART, chart_uuid);
-    if (rc != SQLITE_DONE)
-        error_report("Failed to store active chart, rc = %d", rc);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize statement in store active chart, rc = %d", rc);
-    return;
-}
-
-/*
- * Marks a dimension with UUID as active
- * Input: UUID
- */
-void store_active_dimension(uuid_t *dimension_uuid)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("Database has not been initialized");
-        return;
-    }
-
-    if (unlikely(!dimension_uuid))
-        return;
-
-    rc = store_active_uuid_object(&res, SQL_STORE_ACTIVE_DIMENSION, dimension_uuid);
-    if (rc != SQLITE_DONE)
-        error_report("Failed to store active dimension, rc = %d", rc);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize statement in store active dimension, rc = %d", rc);
-    return;
-}
-
 static int check_table_integrity_cb(void *data, int argc, char **argv, char **column)
 {
     int *status = data;
@@ -273,7 +204,7 @@ static int check_table_integrity(char *table)
         strcpy(wstr,"PRAGMA integrity_check;");
     }
 
-    int rc = sqlite3_exec(db_meta, wstr, check_table_integrity_cb, (void *) &status, &err_msg);
+    int rc = sqlite3_exec_monitored(db_meta, wstr, check_table_integrity_cb, (void *) &status, &err_msg);
     if (rc != SQLITE_OK) {
         error_report("SQLite error during database integrity check for %s, rc = %d (%s)",
                      table ? table : "the entire database", rc, err_msg);
@@ -306,14 +237,13 @@ static void rebuild_chart()
     info("Rebuilding chart table");
     for (int i = 0; rebuild_chart_commands[i]; i++) {
         info("Executing %s", rebuild_chart_commands[i]);
-        rc = sqlite3_exec(db_meta, rebuild_chart_commands[i], 0, 0, &err_msg);
+        rc = sqlite3_exec_monitored(db_meta, rebuild_chart_commands[i], 0, 0, &err_msg);
         if (rc != SQLITE_OK) {
             error_report("SQLite error during database setup, rc = %d (%s)", rc, err_msg);
             error_report("SQLite failed statement %s", rebuild_chart_commands[i]);
             sqlite3_free(err_msg);
         }
     }
-    return;
 }
 
 const char *rebuild_dimension_commands[] = {
@@ -339,14 +269,13 @@ void rebuild_dimension()
     info("Rebuilding dimension table");
     for (int i = 0; rebuild_dimension_commands[i]; i++) {
         info("Executing %s", rebuild_dimension_commands[i]);
-        rc = sqlite3_exec(db_meta, rebuild_dimension_commands[i], 0, 0, &err_msg);
+        rc = sqlite3_exec_monitored(db_meta, rebuild_dimension_commands[i], 0, 0, &err_msg);
         if (rc != SQLITE_OK) {
             error_report("SQLite error during database setup, rc = %d (%s)", rc, err_msg);
             error_report("SQLite failed statement %s", rebuild_dimension_commands[i]);
             sqlite3_free(err_msg);
         }
     }
-    return;
 }
 
 static int attempt_database_fix()
@@ -366,7 +295,7 @@ int init_database_batch(sqlite3 *database, int rebuild, int init_type, const cha
     char *err_msg = NULL;
     for (int i = 0; batch[i]; i++) {
         debug(D_METADATALOG, "Executing %s", batch[i]);
-        rc = sqlite3_exec(database, batch[i], 0, 0, &err_msg);
+        rc = sqlite3_exec_monitored(database, batch[i], 0, 0, &err_msg);
         if (rc != SQLITE_OK) {
             error_report("SQLite error during database %s, rc = %d (%s)", init_type ? "cleanup" : "setup", rc, err_msg);
             error_report("SQLite failed statement %s", batch[i]);
@@ -384,6 +313,24 @@ int init_database_batch(sqlite3 *database, int rebuild, int init_type, const cha
     return 0;
 }
 
+static void sqlite_uuid_parse(sqlite3_context *context, int argc, sqlite3_value **argv)
+{
+    uuid_t  uuid;
+
+    if ( argc != 1 ){
+        sqlite3_result_null(context);
+        return ;
+    }
+    int rc = uuid_parse((const char *) sqlite3_value_text(argv[0]), uuid);
+    if (rc == -1)  {
+        sqlite3_result_null(context);
+        return ;
+    }
+
+    sqlite3_result_blob(context, &uuid, sizeof(uuid_t), SQLITE_TRANSIENT);
+}
+
+
 /*
  * Initialize the SQLite database
  * Return 0 on success
@@ -437,7 +384,7 @@ int sql_init_database(db_check_action_type_t rebuild, int memory)
     if (rebuild & DB_CHECK_RECLAIM_SPACE) {
         if (!(rebuild & DB_CHECK_CONT))
             info("Reclaiming space of %s", sqlite_database);
-        rc = sqlite3_exec(db_meta, "VACUUM;", 0, 0, &err_msg);
+        rc = sqlite3_exec_monitored(db_meta, "VACUUM;", 0, 0, &err_msg);
         if (rc != SQLITE_OK) {
             error_report("Failed to execute VACUUM rc = %d (%s)", rc, err_msg);
             sqlite3_free(err_msg);
@@ -497,12 +444,14 @@ int sql_init_database(db_check_action_type_t rebuild, int memory)
     if (init_database_batch(db_meta, rebuild, 0, &database_cleanup[0]))
         return 1;
 
-    fatal_assert(0 == uv_mutex_init(&sqlite_transaction_lock));
     info("SQLite database initialization completed");
 
     for (int i = 0; i < MAX_PREPARED_STATEMENTS; i++)
         (void)pthread_key_create(&key_pool[i], release_statement);
 
+    rc = sqlite3_create_function(db_meta, "u2h", 1, SQLITE_ANY | SQLITE_DETERMINISTIC, 0, sqlite_uuid_parse, 0, 0);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to register internal u2h function");
     return 0;
 }
 
@@ -523,233 +472,9 @@ void sql_close_database(void)
     rc = sqlite3_close_v2(db_meta);
     if (unlikely(rc != SQLITE_OK))
         error_report("Error %d while closing the SQLite database, %s", rc, sqlite3_errstr(rc));
-    return;
-}
-
-#define FIND_UUID_TYPE  "select 1 from host where host_id = @uuid union select 2 from chart where chart_id = @uuid union select 3 from dimension where dim_id = @uuid;"
-
-int find_uuid_type(uuid_t *uuid)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-    int uuid_type = 3;
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, FIND_UUID_TYPE, &res);
-        if (rc != SQLITE_OK) {
-            error_report("Failed to bind prepare statement to find UUID type in the database");
-            return 0;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, uuid, sizeof(*uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_step(res);
-    if (likely(rc == SQLITE_ROW))
-        uuid_type = sqlite3_column_int(res, 0);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement during find uuid type, rc = %d", rc);
-
-    return uuid_type;
-
-bind_fail:
-    return 0;
-}
-
-int find_dimension_uuid(RRDSET *st, RRDDIM *rd, uuid_t *store_uuid)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-    int status = 1;
-
-    if (unlikely(!db_meta) && default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-        return 1;
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, SQL_FIND_DIMENSION_UUID, &res);
-        if (rc != SQLITE_OK) {
-            error_report("Failed to bind prepare statement to lookup dimension UUID in the database");
-            return 1;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, st->chart_uuid, sizeof(*st->chart_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 2, rd->id, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 3, rd->name, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_step(res);
-    if (likely(rc == SQLITE_ROW)) {
-        uuid_copy(*store_uuid, *((uuid_t *) sqlite3_column_blob(res, 0)));
-        status = 0;
-    }
-    else {
-        uuid_generate(*store_uuid);
-        status = sql_store_dimension(store_uuid, st->chart_uuid, rd->id, rd->name, rd->multiplier, rd->divisor, rd->algorithm);
-        if (unlikely(status))
-            error_report("Failed to store dimension metadata in the database");
-    }
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement find dimension uuid, rc = %d", rc);
-    return status;
-
-bind_fail:
-    error_report("Failed to bind input parameter to perform dimension UUID database lookup, rc = %d", rc);
-    return 1;
-}
-
-#define DELETE_DIMENSION_UUID   "delete from dimension where dim_id = @uuid;"
-
-void delete_dimension_uuid(uuid_t *dimension_uuid)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-
-#ifdef NETDATA_INTERNAL_CHECKS
-    char uuid_str[GUID_LEN + 1];
-    uuid_unparse_lower(*dimension_uuid, uuid_str);
-    debug(D_METADATALOG,"Deleting dimension uuid %s", uuid_str);
-#endif
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, DELETE_DIMENSION_UUID, &res);
-        if (rc != SQLITE_OK) {
-            error_report("Failed to prepare statement to delete a dimension uuid");
-            return;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, dimension_uuid,  sizeof(*dimension_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_step(res);
-    if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed to delete dimension uuid, rc = %d", rc);
-
-bind_fail:
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement when deleting dimension UUID, rc = %d", rc);
-    return;
-}
-
-/*
- * Do a database lookup to find the UUID of a chart
- *
- */
-uuid_t *find_chart_uuid(RRDHOST *host, const char *type, const char *id, const char *name)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    uuid_t *uuid = NULL;
-    int rc;
-
-    if (unlikely(!db_meta) && default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-        return NULL;
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, SQL_FIND_CHART_UUID, &res);
-        if (rc != SQLITE_OK) {
-            error_report("Failed to prepare statement to lookup chart UUID in the database");
-            return NULL;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, &host->host_uuid, sizeof(host->host_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-            goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 2, type, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 3, id, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 4, name ? name : id, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_step(res);
-    if (likely(rc == SQLITE_ROW)) {
-        uuid = mallocz(sizeof(uuid_t));
-        uuid_copy(*uuid, sqlite3_column_blob(res, 0));
-    }
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement when searching for a chart UUID, rc = %d", rc);
-
-#ifdef NETDATA_INTERNAL_CHECKS
-    char  uuid_str[GUID_LEN + 1];
-    if (likely(uuid)) {
-        uuid_unparse_lower(*uuid, uuid_str);
-        debug(D_METADATALOG, "Found UUID %s for chart %s.%s", uuid_str, type, name ? name : id);
-    }
-    else
-        debug(D_METADATALOG, "UUID not found for chart %s.%s", type, name ? name : id);
-#endif
-    return uuid;
-
-bind_fail:
-    error_report("Failed to bind input parameter to perform chart UUID database lookup, rc = %d", rc);
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement when searching for a chart UUID, rc = %d", rc);
-    return NULL;
-}
-
-int update_chart_metadata(uuid_t *chart_uuid, RRDSET *st, const char *id, const char *name)
-{
-    int rc;
-
-    if (unlikely(!db_meta) && default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-        return 0;
-
-    rc = sql_store_chart(
-        chart_uuid, &st->rrdhost->host_uuid, st->type, id, name, st->family, st->context, st->title, st->units, st->plugin_name,
-        st->module_name, st->priority, st->update_every, st->chart_type, st->rrd_memory_mode, st->entries);
-
-    return rc;
-}
-
-uuid_t *create_chart_uuid(RRDSET *st, const char *id, const char *name)
-{
-    uuid_t *uuid = NULL;
-    int rc;
-
-    uuid = mallocz(sizeof(uuid_t));
-    uuid_generate(*uuid);
-
-#ifdef NETDATA_INTERNAL_CHECKS
-    char uuid_str[GUID_LEN + 1];
-    uuid_unparse_lower(*uuid, uuid_str);
-    debug(D_METADATALOG,"Generating uuid [%s] for chart %s under host %s", uuid_str, st->id, st->rrdhost->hostname);
-#endif
-
-    rc = update_chart_metadata(uuid, st, id, name);
-
-    if (unlikely(rc))
-        error_report("Failed to store chart metadata in the database");
-
-    return uuid;
 }
 
-static int exec_statement_with_uuid(const char *sql, uuid_t *uuid)
+int exec_statement_with_uuid(const char *sql, uuid_t *uuid)
 {
     int rc, result = 1;
     sqlite3_stmt *res = NULL;
@@ -763,7 +488,7 @@ static int exec_statement_with_uuid(const char *sql, uuid_t *uuid)
     rc = sqlite3_bind_blob(res, 1, uuid, sizeof(*uuid), SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind host parameter to %s, rc = %d", sql, rc);
-        goto failed;
+        goto skip;
     }
 
     rc = execute_insert(res);
@@ -772,7 +497,7 @@ static int exec_statement_with_uuid(const char *sql, uuid_t *uuid)
     else
         error_report("Failed to execute %s, rc = %d", sql, rc);
 
-failed:
+skip:
     rc = sqlite3_finalize(res);
     if (unlikely(rc != SQLITE_OK))
         error_report("Failed to finalize statement %s, rc = %d", sql, rc);
@@ -780,445 +505,13 @@ failed:
 }
 
 
-// Migrate all hosts with hops zero to this host_uuid
-void migrate_localhost(uuid_t *host_uuid)
-{
-    int rc;
-
-    rc = exec_statement_with_uuid("UPDATE chart SET host_id = @host_id WHERE host_id in (SELECT host_id FROM host where host_id <> @host_id and hops = 0); ", host_uuid);
-    if (!rc)
-        rc = exec_statement_with_uuid("DELETE FROM host WHERE hops = 0 AND host_id <> @host_id; ", host_uuid);
-    if (!rc)
-        db_execute("DELETE FROM node_instance WHERE host_id NOT IN (SELECT host_id FROM host);");
-
-}
-
-int sql_store_host(
-    uuid_t *host_uuid, const char *hostname, const char *registry_hostname, int update_every, const char *os,
-    const char *tzone, const char *tags, int hops)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-            return 0;
-        error_report("Database has not been initialized");
-        return 1;
-    }
-
-    if (unlikely((!res))) {
-        rc = prepare_statement(db_meta, SQL_STORE_HOST, &res);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement to store host, rc = %d", rc);
-            return 1;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, host_uuid, sizeof(*host_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 2, hostname, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 3, registry_hostname, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 4, update_every);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 5, os, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 6, tzone, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 7, tags, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 8, hops);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    int store_rc = sqlite3_step(res);
-    if (unlikely(store_rc != SQLITE_DONE))
-        error_report("Failed to store host %s, rc = %d", hostname, rc);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement to store host %s, rc = %d", hostname, rc);
-
-    return !(store_rc == SQLITE_DONE);
-bind_fail:
-    error_report("Failed to bind parameter to store host %s, rc = %d", hostname, rc);
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement to store host %s, rc = %d", hostname, rc);
-    return 1;
-}
-
-//
-// Store host and host system info information in the database
-#define SQL_STORE_HOST_INFO "INSERT OR REPLACE INTO host " \
-        "(host_id, hostname, registry_hostname, update_every, os, timezone," \
-        "tags, hops, memory_mode, abbrev_timezone, utc_offset, program_name, program_version," \
-        "entries, health_enabled) " \
-        "values (@host_id, @hostname, @registry_hostname, @update_every, @os, @timezone, @tags, @hops, @memory_mode, " \
-        "@abbrev_timezone, @utc_offset, @program_name, @program_version, " \
-        "@entries, @health_enabled);"
-
-int sql_store_host_info(RRDHOST *host)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-            return 0;
-        error_report("Database has not been initialized");
-        return 1;
-    }
-
-    if (unlikely((!res))) {
-        rc = prepare_statement(db_meta, SQL_STORE_HOST_INFO, &res);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement to store host, rc = %d", rc);
-            return 1;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, &host->host_uuid, sizeof(host->host_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = bind_text_null(res, 2, host->hostname, 0);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = bind_text_null(res, 3, host->registry_hostname, 1);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 4, host->rrd_update_every);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = bind_text_null(res, 5, host->os, 1);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = bind_text_null(res, 6, host->timezone, 1);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = bind_text_null(res, 7, host->tags, 1);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 8, host->system_info ? host->system_info->hops : 0);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 9, host->rrd_memory_mode);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = bind_text_null(res, 10, host->abbrev_timezone, 1);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 11, host->utc_offset);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = bind_text_null(res, 12, host->program_name, 1);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = bind_text_null(res, 13, host->program_version, 1);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int64(res, 14, host->rrd_history_entries);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 15, host->health_enabled);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    int store_rc = sqlite3_step(res);
-    if (unlikely(store_rc != SQLITE_DONE))
-        error_report("Failed to store host %s, rc = %d", host->hostname, rc);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement to store host %s, rc = %d", host->hostname, rc);
-
-    return !(store_rc == SQLITE_DONE);
-bind_fail:
-    error_report("Failed to bind parameter to store host %s, rc = %d", host->hostname, rc);
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement to store host %s, rc = %d", host->hostname, rc);
-    return 1;
-}
-
-/*
- * Store a chart in the database
- */
-
-int sql_store_chart(
-    uuid_t *chart_uuid, uuid_t *host_uuid, const char *type, const char *id, const char *name, const char *family,
-    const char *context, const char *title, const char *units, const char *plugin, const char *module, long priority,
-    int update_every, int chart_type, int memory_mode, long history_entries)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc, param = 0;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-            return 0;
-        error_report("Database has not been initialized");
-        return 1;
-    }
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, SQL_STORE_CHART, &res);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement to store chart, rc = %d", rc);
-            return 1;
-        }
-    }
-
-    param++;
-    rc = sqlite3_bind_blob(res, 1, chart_uuid, sizeof(*chart_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_blob(res, 2, host_uuid, sizeof(*host_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 3, type, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 4, id, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    if (name && *name)
-        rc = sqlite3_bind_text(res, 5, name, -1, SQLITE_STATIC);
-    else
-        rc = sqlite3_bind_null(res, 5);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 6, family, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 7, context, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 8, title, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 9, units, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 10, plugin, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 11, module, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_int(res, 12, priority);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_int(res, 13, update_every);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_int(res, 14, chart_type);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_int(res, 15, memory_mode);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_int(res, 16, history_entries);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = execute_insert(res);
-    if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed to store chart, rc = %d", rc);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement in chart store function, rc = %d", rc);
-
-    return 0;
-
-bind_fail:
-    error_report("Failed to bind parameter %d to store chart, rc = %d", param, rc);
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement in chart store function, rc = %d", rc);
-    return 1;
-}
-
-/*
- * Store a dimension
- */
-int sql_store_dimension(
-    uuid_t *dim_uuid, uuid_t *chart_uuid, const char *id, const char *name, collected_number multiplier,
-    collected_number divisor, int algorithm)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-            return 0;
-        error_report("Database has not been initialized");
-        return 1;
-    }
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, SQL_STORE_DIMENSION, &res);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement to store dimension, rc = %d", rc);
-            return 1;
-        }
-    }
-
-    rc = sqlite3_bind_blob(res, 1, dim_uuid, sizeof(*dim_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_blob(res, 2, chart_uuid, sizeof(*chart_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 3, id, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_text(res, 4, name, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 5, multiplier);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 6, divisor);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = sqlite3_bind_int(res, 7, algorithm);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = execute_insert(res);
-    if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed to store dimension, rc = %d", rc);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement in store dimension, rc = %d", rc);
-    return 0;
-
-bind_fail:
-    error_report("Failed to bind parameter to store dimension, rc = %d", rc);
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement in store dimension, rc = %d", rc);
-    return 1;
-}
-
-/*
- * Store set option for a dimension
- */
-int sql_set_dimension_option(uuid_t *dim_uuid, char *option)
-{
-    sqlite3_stmt *res = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-            return 0;
-        error_report("Database has not been initialized");
-        return 1;
-    }
-
-    rc = sqlite3_prepare_v2(db_meta, "UPDATE dimension SET options = @options WHERE dim_id = @dim_id", -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to update dimension options");
-        return 0;
-    };
-
-    rc = sqlite3_bind_blob(res, 2, dim_uuid, sizeof(*dim_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    if (!option || !strcmp(option,"unhide"))
-        rc = sqlite3_bind_null(res, 1);
-    else
-        rc = sqlite3_bind_text(res, 1, option, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = execute_insert(res);
-    if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed to update dimension option, rc = %d", rc);
-
-bind_fail:
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize statement in update dimension options, rc = %d", rc);
-    return 0;
-}
-
 
 //
-// Support for archived charts
+// Support for archived charts (TO BE REMOVED)
 //
 #define SELECT_DIMENSION "select d.id, d.name from dimension d where d.chart_id = @chart_uuid;"
 
-void sql_rrdim2json(sqlite3_stmt *res_dim, uuid_t *chart_uuid, BUFFER *wb, size_t *dimensions_count)
+static void sql_rrdim2json(sqlite3_stmt *res_dim, uuid_t *chart_uuid, BUFFER *wb, size_t *dimensions_count)
 {
     int rc;
 
@@ -1229,7 +522,7 @@ void sql_rrdim2json(sqlite3_stmt *res_dim, uuid_t *chart_uuid, BUFFER *wb, size_
     int dimensions = 0;
     buffer_sprintf(wb, "\t\t\t\"dimensions\": {\n");
 
-    while (sqlite3_step(res_dim) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res_dim) == SQLITE_ROW) {
         if (dimensions)
             buffer_strcat(wb, ",\n\t\t\t\t\"");
         else
@@ -1291,11 +584,11 @@ void sql_rrdset2json(RRDHOST *host, BUFFER *wb)
                        ",\n\t\"memory_mode\": \"%s\""
                        ",\n\t\"custom_info\": \"%s\""
                        ",\n\t\"charts\": {"
-        , host->hostname
-        , host->program_version
+        , rrdhost_hostname(host)
+        , rrdhost_program_version(host)
         , get_release_channel()
-        , host->os
-        , host->timezone
+        , rrdhost_os(host)
+        , rrdhost_timezone(host)
         , host->rrd_update_every
         , host->rrd_history_entries
         , rrd_memory_mode_name(host->rrd_memory_mode)
@@ -1305,7 +598,7 @@ void sql_rrdset2json(RRDHOST *host, BUFFER *wb)
     size_t c = 0;
     size_t dimensions = 0;
 
-    while (sqlite3_step(res_chart) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res_chart) == SQLITE_ROW) {
         char id[512];
         sprintf(id, "%s.%s", sqlite3_column_text(res_chart, 3), sqlite3_column_text(res_chart, 1));
         RRDSET *st = rrdset_find(host, id);
@@ -1386,7 +679,7 @@ void sql_rrdset2json(RRDHOST *host, BUFFER *wb)
                       "\n\t\t\t\"hostname\": \"%s\""
                       "\n\t\t}"
                     , (found > 0) ? "," : ""
-                    , h->hostname
+                    , rrdhost_hostname(h)
                 );
 
                 found++;
@@ -1400,7 +693,7 @@ void sql_rrdset2json(RRDHOST *host, BUFFER *wb)
             , "\n\t\t{"
               "\n\t\t\t\"hostname\": \"%s\""
               "\n\t\t}"
-            , host->hostname
+            , rrdhost_hostname(host)
         );
     }
 
@@ -1414,95 +707,6 @@ failed:
     rc = sqlite3_finalize(res_chart);
     if (unlikely(rc != SQLITE_OK))
         error_report("Failed to finalize the prepared statement when reading archived charts");
-
-    return;
-}
-
-void free_temporary_host(RRDHOST *host)
-{
-    if (host) {
-        freez(host->hostname);
-        freez((char *)host->os);
-        freez((char *)host->tags);
-        freez((char *)host->timezone);
-        freez(host->program_name);
-        freez(host->program_version);
-        freez(host->registry_hostname);
-        freez(host->system_info);
-        freez(host);
-    }
-}
-
-#define SELECT_HOST "select host_id, registry_hostname, update_every, os, timezone, tags from host where hostname = @hostname order by rowid desc;"
-#define SELECT_HOST_BY_UUID "select h.host_id, h.registry_hostname, h.update_every, h.os, h.timezone, h.tags from host h, node_instance ni " \
-    "where (ni.host_id = @host_id or ni.node_id = @host_id) AND ni.host_id = h.host_id;"
-
-RRDHOST *sql_create_host_by_uuid(char *hostname)
-{
-    int rc;
-    RRDHOST *host = NULL;
-    uuid_t host_uuid;
-
-    sqlite3_stmt *res = NULL;
-
-    rc = uuid_parse(hostname, host_uuid);
-    if (!rc) {
-        rc = sqlite3_prepare_v2(db_meta, SELECT_HOST_BY_UUID, -1, &res, 0);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement to fetch host by uuid");
-            return NULL;
-        }
-        rc = sqlite3_bind_blob(res, 1, &host_uuid, sizeof(host_uuid), SQLITE_STATIC);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to bind host_id parameter to fetch host information");
-            goto failed;
-        }
-    }
-    else {
-        rc = sqlite3_prepare_v2(db_meta, SELECT_HOST, -1, &res, 0);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement to fetch host by hostname");
-            return NULL;
-        }
-        rc = sqlite3_bind_text(res, 1, hostname, -1, SQLITE_STATIC);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to bind hostname parameter to fetch host information");
-            goto failed;
-        }
-    }
-
-    rc = sqlite3_step(res);
-    if (unlikely(rc != SQLITE_ROW)) {
-        error_report("Failed to find hostname %s", hostname);
-        goto failed;
-    }
-
-    char uuid_str[GUID_LEN + 1];
-    uuid_unparse_lower(*((uuid_t *) sqlite3_column_blob(res, 0)), uuid_str);
-
-    host = callocz(1, sizeof(RRDHOST));
-
-    set_host_properties(host, sqlite3_column_int(res, 2), RRD_MEMORY_MODE_DBENGINE, hostname,
-                        (char *) sqlite3_column_text(res, 1), (const char *) uuid_str,
-                        (char *) sqlite3_column_text(res, 3), (char *) sqlite3_column_text(res, 5),
-                        (char *) sqlite3_column_text(res, 4), NULL, 0, NULL, NULL);
-
-    uuid_copy(host->host_uuid, *((uuid_t *) sqlite3_column_blob(res, 0)));
-
-    host->system_info = callocz(1, sizeof(*host->system_info));;
-    rrdhost_flag_set(host, RRDHOST_FLAG_ARCHIVED);
-
-#ifdef ENABLE_DBENGINE
-    for(int tier = 0; tier < storage_tiers ; tier++)
-        host->storage_instance[tier] = (STORAGE_INSTANCE *)multidb_ctx[tier];
-#endif
-
-failed:
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize the prepared statement when reading host information");
-
-    return host;
 }
 
 void db_execute(const char *cmd)
@@ -1511,35 +715,23 @@ void db_execute(const char *cmd)
     int cnt = 0;
     while (cnt < SQL_MAX_RETRY) {
         char *err_msg;
-        rc = sqlite3_exec(db_meta, cmd, 0, 0, &err_msg);
+        rc = sqlite3_exec_monitored(db_meta, cmd, 0, 0, &err_msg);
         if (rc != SQLITE_OK) {
             error_report("Failed to execute '%s', rc = %d (%s) -- attempt %d", cmd, rc, err_msg, cnt);
             sqlite3_free(err_msg);
             if (likely(rc == SQLITE_BUSY || rc == SQLITE_LOCKED)) {
                 usleep(SQLITE_INSERT_DELAY * USEC_PER_MS);
             }
-            else break;
+            else
+                break;
         }
         else
             break;
+
         ++cnt;
     }
-    return;
-}
-
-void db_lock(void)
-{
-    uv_mutex_lock(&sqlite_transaction_lock);
-    return;
 }
 
-void db_unlock(void)
-{
-    uv_mutex_unlock(&sqlite_transaction_lock);
-    return;
-}
-
-
 #define SELECT_MIGRATED_FILE    "select 1 from metadata_migration where filename = @path;"
 
 int file_is_migrated(char *path)
@@ -1559,7 +751,7 @@ int file_is_migrated(char *path)
         return 0;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
 
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
         error_report("Failed to finalize the prepared statement when checking if metadata file is migrated");
@@ -1587,7 +779,7 @@ void add_migrated_file(char *path, uint64_t file_size)
         return;
     }
 
-    rc = sqlite3_bind_int64(res, 2, file_size);
+    rc = sqlite3_bind_int64(res, 2, (sqlite_int64) file_size);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind size parameter to store migration information");
         return;
@@ -1599,494 +791,9 @@ void add_migrated_file(char *path, uint64_t file_size)
 
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
         error_report("Failed to finalize the prepared statement when checking if metadata file is migrated");
-
-    return;
-}
-
-static int sql_store_label(sqlite3_stmt *res, uuid_t *uuid, int source_type, const char *label, const char *value)
-{
-    int rc;
-
-    rc = sqlite3_bind_blob(res, 1, uuid, sizeof(*uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind UUID parameter to store label information");
-        goto skip_store;
-    }
-
-    rc = sqlite3_bind_int(res, 2, source_type);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind type parameter to store label information");
-        goto skip_store;
-    }
-
-    rc = sqlite3_bind_text(res, 3, label, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind label parameter to store label information");
-        goto skip_store;
-    }
-
-    rc = sqlite3_bind_text(res, 4, value, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind value parameter to store label information");
-        goto skip_store;
-    }
-
-    rc = execute_insert(res);
-    if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed to store label entry, rc = %d", rc);
-
-skip_store:
-    if (unlikely(sqlite3_reset(res) != SQLITE_OK))
-        error_report("Failed to reset the prepared statement when storing label information");
-
-    return rc != SQLITE_DONE;
-}
-
-#define SQL_INS_CHART_LABEL "insert or replace into chart_label " \
-    "(chart_id, source_type, label_key, label_value, date_created) " \
-    "values (@chart, @source, @label, @value, unixepoch());"
-
-void sql_store_chart_label(uuid_t *chart_uuid, int source_type, char *label, char *value)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("Database has not been initialized");
-        return;
-    }
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, SQL_INS_CHART_LABEL, &res);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement store chart labels");
-            return;
-        }
-    }
-
-    sql_store_label(res, chart_uuid, source_type, label, value);
-
-    return;
-}
-
-#define SQL_INS_HOST_LABEL "INSERT OR REPLACE INTO host_label " \
-    "(host_id, source_type, label_key, label_value, date_created) " \
-    "values (@chart, @source, @label, @value, unixepoch());"
-
-static void sql_store_host_label(uuid_t *host_uuid, int source_type, const char *label, const char *value)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("Database has not been initialized");
-        return;
-    }
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, SQL_INS_HOST_LABEL, &res);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement store chart labels");
-            return;
-        }
-    }
-
-    (void) sql_store_label(res, host_uuid, source_type, label, value);
-}
-
-int find_dimension_first_last_t(char *machine_guid, char *chart_id, char *dim_id,
-                                uuid_t *uuid, time_t *first_entry_t, time_t *last_entry_t, uuid_t *rrdeng_uuid, int tier)
-{
-#ifdef ENABLE_DBENGINE
-    int rc;
-    uuid_t  legacy_uuid;
-    uuid_t  multihost_legacy_uuid;
-    time_t dim_first_entry_t, dim_last_entry_t;
-
-    rc = rrdeng_metric_latest_time_by_uuid(uuid, &dim_first_entry_t, &dim_last_entry_t, tier);
-    if (unlikely(rc)) {
-        rrdeng_generate_legacy_uuid(dim_id, chart_id, &legacy_uuid);
-        rc = rrdeng_metric_latest_time_by_uuid(&legacy_uuid, &dim_first_entry_t, &dim_last_entry_t, tier);
-        if (likely(rc)) {
-            rrdeng_convert_legacy_uuid_to_multihost(machine_guid, &legacy_uuid, &multihost_legacy_uuid);
-            rc = rrdeng_metric_latest_time_by_uuid(&multihost_legacy_uuid, &dim_first_entry_t, &dim_last_entry_t, tier);
-            if (likely(!rc))
-                uuid_copy(*rrdeng_uuid, multihost_legacy_uuid);
-        }
-        else
-            uuid_copy(*rrdeng_uuid, legacy_uuid);
-    }
-    else
-        uuid_copy(*rrdeng_uuid, *uuid);
-
-    if (likely(!rc)) {
-        *first_entry_t = MIN(*first_entry_t, dim_first_entry_t);
-        *last_entry_t = MAX(*last_entry_t, dim_last_entry_t);
-    }
-    return rc;
-#else
-    UNUSED(machine_guid);
-    UNUSED(chart_id);
-    UNUSED(dim_id);
-    UNUSED(uuid);
-    UNUSED(first_entry_t);
-    UNUSED(last_entry_t);
-    UNUSED(rrdeng_uuid);
-    return 1;
-#endif
-}
-#include "../storage_engine.h"
-#ifdef ENABLE_DBENGINE
-static RRDDIM *create_rrdim_entry(ONEWAYALLOC *owa, RRDSET *st, char *id, char *name, uuid_t *metric_uuid)
-{
-    STORAGE_ENGINE *eng = storage_engine_get(RRD_MEMORY_MODE_DBENGINE);
-
-    if (unlikely(!eng))
-        return NULL;
-
-    RRDDIM *rd = onewayalloc_callocz(owa, 1, sizeof(*rd));
-    rd->rrdset = st;
-    rd->update_every = st->update_every;
-    rd->last_stored_value = NAN;
-    rrddim_flag_set(rd, RRDDIM_FLAG_NONE);
-
-    uuid_copy(rd->metric_uuid, *metric_uuid);
-    rd->id = onewayalloc_strdupz(owa, id);
-    rd->name = onewayalloc_strdupz(owa, name);
-
-    for(int tier = 0; tier < storage_tiers ;tier++) {
-        rd->tiers[tier] = onewayalloc_callocz(owa, 1, sizeof(*rd->tiers[tier]));
-        rd->rrd_memory_mode = RRD_MEMORY_MODE_DBENGINE;
-        rd->tiers[tier]->tier_grouping = get_tier_grouping(tier);
-        rd->tiers[tier]->mode = RRD_MEMORY_MODE_DBENGINE;
-        rd->tiers[tier]->query_ops.init = rrdeng_load_metric_init;
-        rd->tiers[tier]->query_ops.next_metric = rrdeng_load_metric_next;
-        rd->tiers[tier]->query_ops.is_finished = rrdeng_load_metric_is_finished;
-        rd->tiers[tier]->query_ops.finalize = rrdeng_load_metric_finalize;
-        rd->tiers[tier]->query_ops.latest_time = rrdeng_metric_latest_time;
-        rd->tiers[tier]->query_ops.oldest_time = rrdeng_metric_oldest_time;
-        rd->tiers[tier]->db_metric_handle = eng->api.init(rd, st->rrdhost->storage_instance[tier]);
-    }
-
-    return rd;
-}
-#endif
-
-#define SELECT_CHART_CONTEXT  "select d.dim_id, d.id, d.name, c.id, c.type, c.name, c.update_every, c.chart_id, " \
-    "c.context, CASE WHEN d.options = 'hidden' THEN 1 else 0 END from chart c, " \
-    "dimension d, host h " \
-    "where d.chart_id = c.chart_id and c.host_id = h.host_id and c.host_id = @host_id and c.context = @context " \
-    "order by c.chart_id asc, c.type||c.id desc;"
-
-#define SELECT_CHART_SINGLE  "select d.dim_id, d.id, d.name, c.id, c.type, c.name, c.update_every, c.chart_id, " \
-    "c.context, CASE WHEN d.options = 'hidden' THEN 1 else 0 END from chart c, " \
-    "dimension d, host h " \
-    "where d.chart_id = c.chart_id and c.host_id = h.host_id and c.host_id = @host_id and c.type||'.'||c.id = @chart " \
-    "order by c.chart_id asc, c.type||'.'||c.id desc;"
-
-void sql_build_context_param_list(ONEWAYALLOC  *owa, struct context_param **param_list, RRDHOST *host, char *context, char *chart)
-{
-#ifdef ENABLE_DBENGINE
-    int rc;
-
-    if (unlikely(!param_list) || host->rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-        return;
-
-    if (unlikely(!(*param_list))) {
-        *param_list = onewayalloc_mallocz(owa, sizeof(struct context_param));
-        (*param_list)->first_entry_t = LONG_MAX;
-        (*param_list)->last_entry_t = 0;
-        (*param_list)->rd = NULL;
-        (*param_list)->flags = CONTEXT_FLAGS_ARCHIVE;
-        if (chart)
-            (*param_list)->flags |= CONTEXT_FLAGS_CHART;
-        else
-            (*param_list)->flags |= CONTEXT_FLAGS_CONTEXT;
-    }
-
-    sqlite3_stmt *res = NULL;
-
-    if (context)
-        rc = sqlite3_prepare_v2(db_meta, SELECT_CHART_CONTEXT, -1, &res, 0);
-    else
-        rc = sqlite3_prepare_v2(db_meta, SELECT_CHART_SINGLE, -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to fetch host archived charts");
-        return;
-    }
-
-    rc = sqlite3_bind_blob(res, 1, &host->host_uuid, sizeof(host->host_uuid), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind host parameter to fetch archived charts");
-        goto failed;
-    }
-
-    if (context)
-        rc = sqlite3_bind_text(res, 2, context, -1, SQLITE_STATIC);
-    else
-        rc = sqlite3_bind_text(res, 2, chart, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind host parameter to fetch archived charts");
-        goto failed;
-    }
-
-    RRDSET *st = NULL;
-    char machine_guid[GUID_LEN + 1];
-    uuid_unparse_lower(host->host_uuid, machine_guid);
-    uuid_t rrdeng_uuid;
-    uuid_t chart_id;
-
-    while (sqlite3_step(res) == SQLITE_ROW) {
-        char id[512];
-        sprintf(id, "%s.%s", sqlite3_column_text(res, 3), sqlite3_column_text(res, 1));
-
-        if (!st || uuid_compare(*(uuid_t *)sqlite3_column_blob(res, 7), chart_id)) {
-            if (unlikely(st && !st->counter)) {
-                onewayalloc_freez(owa, st->context);
-                onewayalloc_freez(owa, (char *) st->name);
-                onewayalloc_freez(owa, st);
-            }
-            st = onewayalloc_callocz(owa, 1, sizeof(*st));
-            char n[RRD_ID_LENGTH_MAX + 1];
-
-            snprintfz(
-                n, RRD_ID_LENGTH_MAX, "%s.%s", (char *)sqlite3_column_text(res, 4),
-                (char *)sqlite3_column_text(res, 3));
-            st->name = onewayalloc_strdupz(owa, n);
-            st->update_every = sqlite3_column_int(res, 6);
-            st->counter = 0;
-            if (chart) {
-                st->context = onewayalloc_strdupz(owa, (char *)sqlite3_column_text(res, 8));
-                strncpyz(st->id, chart, RRD_ID_LENGTH_MAX);
-            }
-            uuid_copy(chart_id, *(uuid_t *)sqlite3_column_blob(res, 7));
-            st->last_entry_t = 0;
-            st->rrdhost = host;
-        }
-
-        if (unlikely(find_dimension_first_last_t(machine_guid, (char *)st->name, (char *)sqlite3_column_text(res, 1),
-                (uuid_t *)sqlite3_column_blob(res, 0), &(*param_list)->first_entry_t, &(*param_list)->last_entry_t,
-                &rrdeng_uuid, 0)))
-            continue;
-
-        st->counter++;
-        st->last_entry_t = MAX(st->last_entry_t, (*param_list)->last_entry_t);
-
-        RRDDIM *rd = create_rrdim_entry(owa, st, (char *)sqlite3_column_text(res, 1), (char *)sqlite3_column_text(res, 2), &rrdeng_uuid);
-        if (unlikely(!rd))
-            continue;
-        if (sqlite3_column_int(res, 9) == 1)
-            rrddim_flag_set(rd, RRDDIM_FLAG_HIDDEN);
-        rd->next = (*param_list)->rd;
-        (*param_list)->rd = rd;
-    }
-    if (st) {
-        if (!st->counter) {
-            onewayalloc_freez(owa,st->context);
-            onewayalloc_freez(owa,(char *)st->name);
-            onewayalloc_freez(owa,st);
-        }
-        else
-            if (!st->context && context)
-                st->context = onewayalloc_strdupz(owa,context);
-    }
-
-failed:
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to finalize the prepared statement when reading archived charts");
-#else
-    UNUSED(param_list);
-    UNUSED(host);
-    UNUSED(context);
-    UNUSED(chart);
-#endif
-    return;
-}
-
-
-/*
- * Store a chart hash in the database
- */
-
-#define SQL_STORE_CHART_HASH "insert into v_chart_hash (hash_id, type, id, " \
-    "name, family, context, title, unit, plugin, module, priority, chart_type, last_used, chart_id) " \
-    "values (?1,?2,?3,?4,?5,?6,?7,?8,?9,?10,?11, ?12, unixepoch(), ?13);"
-
-int sql_store_chart_hash(
-    uuid_t *hash_id, uuid_t *chart_id, const char *type, const char *id, const char *name, const char *family,
-    const char *context, const char *title, const char *units, const char *plugin, const char *module, long priority,
-    RRDSET_TYPE chart_type)
-{
-    static __thread sqlite3_stmt *res = NULL;
-    int rc, param = 0;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
-            return 0;
-        error_report("Database has not been initialized");
-        return 1;
-    }
-
-    if (unlikely(!res)) {
-        rc = prepare_statement(db_meta, SQL_STORE_CHART_HASH, &res);
-        if (unlikely(rc != SQLITE_OK)) {
-            error_report("Failed to prepare statement to store chart, rc = %d", rc);
-            return 1;
-        }
-    }
-
-    param++;
-    rc = sqlite3_bind_blob(res, 1, hash_id, sizeof(*hash_id), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 2, type, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 3, id, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    if (name && *name)
-        rc = sqlite3_bind_text(res, 4, name, -1, SQLITE_STATIC);
-    else
-        rc = sqlite3_bind_null(res, 4);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 5, family, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 6, context, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 7, title, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 8, units, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 9, plugin, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_text(res, 10, module, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_int(res, 11, (int) priority);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_int(res, 12, chart_type);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    param++;
-    rc = sqlite3_bind_blob(res, 13, chart_id, sizeof(*chart_id), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK))
-        goto bind_fail;
-
-    rc = execute_insert(res);
-    if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed to store chart hash_id, rc = %d", rc);
-
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement in chart hash_id store function, rc = %d", rc);
-
-    return 0;
-
-    bind_fail:
-    error_report("Failed to bind parameter %d to store chart hash_id, rc = %d", param, rc);
-    rc = sqlite3_reset(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement in chart hash_id store function, rc = %d", rc);
-    return 1;
 }
 
-/*
-  chart hashes are used for cloud communication.
-  if cloud is disabled or openssl is not available (which will prevent cloud connectivity)
-  skip hash calculations
-*/
-void compute_chart_hash(RRDSET *st)
-{
-#if !defined DISABLE_CLOUD && defined ENABLE_HTTPS
-    EVP_MD_CTX *evpctx;
-    unsigned char hash_value[EVP_MAX_MD_SIZE];
-    unsigned int hash_len;
-    char  priority_str[32];
-
-    if (rrdhost_flag_check(st->rrdhost, RRDHOST_FLAG_ACLK_STREAM_CONTEXTS)) {
-        internal_error(true, "Skipping compute_chart_hash for host %s because context streaming is enabled", st->rrdhost->hostname);
-        return;
-    }
 
-    sprintf(priority_str, "%ld", st->priority);
-
-    evpctx = EVP_MD_CTX_create();
-    EVP_DigestInit_ex(evpctx, EVP_sha256(), NULL);
-    //EVP_DigestUpdate(evpctx, st->type, strlen(st->type));
-    EVP_DigestUpdate(evpctx, st->id, strlen(st->id));
-    EVP_DigestUpdate(evpctx, st->name, strlen(st->name));
-    EVP_DigestUpdate(evpctx, st->family, strlen(st->family));
-    EVP_DigestUpdate(evpctx, st->context, strlen(st->context));
-    EVP_DigestUpdate(evpctx, st->title, strlen(st->title));
-    EVP_DigestUpdate(evpctx, st->units, strlen(st->units));
-    EVP_DigestUpdate(evpctx, st->plugin_name, strlen(st->plugin_name));
-    if (st->module_name)
-        EVP_DigestUpdate(evpctx, st->module_name, strlen(st->module_name));
-//    EVP_DigestUpdate(evpctx, priority_str, strlen(priority_str));
-    EVP_DigestUpdate(evpctx, &st->priority, sizeof(st->priority));
-    EVP_DigestUpdate(evpctx, &st->chart_type, sizeof(st->chart_type));
-    EVP_DigestFinal_ex(evpctx, hash_value, &hash_len);
-    EVP_MD_CTX_destroy(evpctx);
-    fatal_assert(hash_len > sizeof(uuid_t));
-
-    char uuid_str[GUID_LEN + 1];
-    uuid_unparse_lower(*((uuid_t *) &hash_value), uuid_str);
-    //info("Calculating HASH %s for chart %s", uuid_str, st->name);
-    uuid_copy(st->state->hash_id, *((uuid_t *) &hash_value));
-
-    (void)sql_store_chart_hash(
-        (uuid_t *)&hash_value,
-        st->chart_uuid,
-        st->type,
-        st->id,
-        st->name,
-        st->family,
-        st->context,
-        st->title,
-        st->units,
-        st->plugin_name,
-        st->module_name,
-        st->priority,
-        st->chart_type);
-#else
-    UNUSED(st);
-#endif
-    return;
-}
 
 #define SQL_STORE_CLAIM_ID  "insert into node_instance " \
     "(host_id, claim_id, date_created) values (@host_id, @claim_id, unixepoch()) " \
@@ -2156,7 +863,6 @@ static inline void set_host_node_id(RRDHOST *host, uuid_t *node_id)
         sql_create_aclk_table(host, &host->host_uuid, node_id);
     else
         uuid_unparse_lower(*node_id, wc->node_id);
-    return;
 }
 
 #define SQL_UPDATE_NODE_ID  "update node_instance set node_id = @node_id where host_id = @host_id;"
@@ -2199,7 +905,7 @@ int update_node_id(uuid_t *host_id, uuid_t *node_id)
     char host_guid[GUID_LEN + 1];
     uuid_unparse_lower(*host_id, host_guid);
     rrd_wrlock();
-    host = rrdhost_find_by_guid(host_guid, 0);
+    host = rrdhost_find_by_guid(host_guid);
     if (likely(host))
             set_host_node_id(host, node_id);
     rrd_unlock();
@@ -2242,7 +948,7 @@ char *get_hostname_by_node_id(char *node)
         goto failed;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
     if (likely(rc == SQLITE_ROW))
         hostname = strdupz((char *)sqlite3_column_text(res, 0));
 
@@ -2280,7 +986,7 @@ int get_host_id(uuid_t *node_id, uuid_t *host_id)
         goto failed;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
     if (likely(rc == SQLITE_ROW && host_id))
         uuid_copy(*host_id, *((uuid_t *) sqlite3_column_blob(res, 0)));
 
@@ -2316,7 +1022,7 @@ int get_node_id(uuid_t *host_id, uuid_t *node_id)
         goto failed;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
     if (likely(rc == SQLITE_ROW && node_id))
         uuid_copy(*node_id, *((uuid_t *) sqlite3_column_blob(res, 0)));
 
@@ -2375,9 +1081,9 @@ failed:
 #define SQL_GET_NODE_INSTANCE_LIST "select ni.node_id, ni.host_id, h.hostname " \
     "from node_instance ni, host h where ni.host_id = h.host_id;"
 
-struct  node_instance_list *get_node_list(void)
+struct node_instance_list *get_node_list(void)
 {
-    struct  node_instance_list *node_list = NULL;
+    struct node_instance_list *node_list = NULL;
     sqlite3_stmt *res = NULL;
     int rc;
 
@@ -2395,7 +1101,7 @@ struct  node_instance_list *get_node_list(void)
 
     int row = 0;
     char host_guid[37];
-    while (sqlite3_step(res) == SQLITE_ROW)
+    while (sqlite3_step_monitored(res) == SQLITE_ROW)
         row++;
 
     if (sqlite3_reset(res) != SQLITE_OK) {
@@ -2405,8 +1111,9 @@ struct  node_instance_list *get_node_list(void)
     node_list = callocz(row + 1, sizeof(*node_list));
     int max_rows = row;
     row = 0;
+    // TODO: Check to remove lock
     rrd_rdlock();
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         if (sqlite3_column_bytes(res, 0) == sizeof(uuid_t))
             uuid_copy(node_list[row].node_id, *((uuid_t *)sqlite3_column_blob(res, 0)));
         if (sqlite3_column_bytes(res, 1) == sizeof(uuid_t)) {
@@ -2414,7 +1121,7 @@ struct  node_instance_list *get_node_list(void)
             uuid_copy(node_list[row].host_id, *host_id);
             node_list[row].queryable = 1;
             uuid_unparse_lower(*host_id, host_guid);
-            RRDHOST *host = rrdhost_find_by_guid(host_guid, 0);
+            RRDHOST *host = rrdhost_find_by_guid(host_guid);
             node_list[row].live = host && (host == localhost || host->receiver) ? 1 : 0;
             node_list[row].hops = (host && host->system_info) ? host->system_info->hops :
                                   uuid_compare(*host_id, localhost->host_uuid) ? 1 : 0;
@@ -2461,7 +1168,7 @@ void sql_load_node_id(RRDHOST *host)
         goto failed;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
     if (likely(rc == SQLITE_ROW)) {
         if (likely(sqlite3_column_bytes(res, 0) == sizeof(uuid_t)))
             set_host_node_id(host, (uuid_t *)sqlite3_column_blob(res, 0));
@@ -2472,8 +1179,6 @@ void sql_load_node_id(RRDHOST *host)
 failed:
     if (unlikely(sqlite3_reset(res) != SQLITE_OK))
         error_report("Failed to reset the prepared statement when loading node instance information");
-
-    return;
 };
 
 
@@ -2494,213 +1199,179 @@ void sql_build_host_system_info(uuid_t *host_id, struct rrdhost_system_info *sys
     rc = sqlite3_bind_blob(res, 1, host_id, sizeof(*host_id), SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind host parameter host information");
-        goto skip_loading;
+        goto skip;
     }
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         rrdhost_set_system_info_variable(system_info, (char *) sqlite3_column_text(res, 0),
                                          (char *) sqlite3_column_text(res, 1));
     }
 
-skip_loading:
+skip:
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
         error_report("Failed to finalize the prepared statement when reading host information");
-    return;
 }
 
+#define SELECT_HOST_LABELS "SELECT label_key, label_value, source_type FROM host_label WHERE host_id = @host_id " \
+    "AND label_key IS NOT NULL AND label_value IS NOT NULL;"
 
-#define SQL_INS_HOST_SYSTEM_INFO "INSERT OR REPLACE INTO host_info " \
-    "(host_id, system_key, system_value, date_created) " \
-    "VALUES (@host, @key, @value, unixepoch());"
-
-void sql_store_host_system_info_key_value(uuid_t *host_id, const char *name, const char *value)
+DICTIONARY *sql_load_host_labels(uuid_t *host_id)
 {
-    sqlite3_stmt *res = NULL;
     int rc;
 
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("Database has not been initialized");
-        return;
-    }
+    DICTIONARY *labels = NULL;
+    sqlite3_stmt *res = NULL;
 
-    rc = sqlite3_prepare_v2(db_meta, SQL_INS_HOST_SYSTEM_INFO, -1, &res, 0);
+    rc = sqlite3_prepare_v2(db_meta, SELECT_HOST_LABELS, -1, &res, 0);
     if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to store system info");
-        return;
+        error_report("Failed to prepare statement to read host information");
+        return NULL;
     }
 
     rc = sqlite3_bind_blob(res, 1, host_id, sizeof(*host_id), SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind host parameter to store system information");
-        goto skip_store;
+        error_report("Failed to bind host parameter host information");
+        goto skip;
     }
 
-    rc = sqlite3_bind_text(res, 2, name, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind label parameter to store name information");
-        goto skip_store;
-    }
+    labels = rrdlabels_create();
 
-    rc = sqlite3_bind_text(res, 3, value, -1, SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind value parameter to store value information");
-        goto skip_store;
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
+        rrdlabels_add(
+            labels,
+            (const char *)sqlite3_column_text(res, 0),
+            (const char *)sqlite3_column_text(res, 1),
+            sqlite3_column_int(res, 2));
     }
 
-    rc = execute_insert(res);
-    if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed to store host system info, rc = %d", rc);
-
-skip_store:
+skip:
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
-        error_report("Failed to finalize the prepared statement when storing  host system information");
-
-    return;
+        error_report("Failed to finalize the prepared statement when reading host information");
+    return labels;
 }
 
-
-void sql_store_host_system_info(uuid_t *host_id, const struct rrdhost_system_info *system_info)
+// Utils
+int bind_text_null(sqlite3_stmt *res, int position, const char *text, bool can_be_null)
 {
-    if (unlikely(!system_info))
-        return;
-
-    if (system_info->container_os_name)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_CONTAINER_OS_NAME", system_info->container_os_name);
-
-    if (system_info->container_os_id)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_CONTAINER_OS_ID", system_info->container_os_id);
-
-    if (system_info->container_os_id_like)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_CONTAINER_OS_ID_LIKE", system_info->container_os_id_like);
-
-    if (system_info->container_os_version)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_CONTAINER_OS_VERSION", system_info->container_os_version);
-
-    if (system_info->container_os_version_id)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_CONTAINER_OS_VERSION_ID", system_info->container_os_version_id);
-
-    if (system_info->host_os_detection)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_CONTAINER_OS_DETECTION", system_info->host_os_detection);
-
-    if (system_info->host_os_name)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_HOST_OS_NAME", system_info->host_os_name);
-
-    if (system_info->host_os_id)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_HOST_OS_ID", system_info->host_os_id);
-
-    if (system_info->host_os_id_like)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_HOST_OS_ID_LIKE", system_info->host_os_id_like);
-
-    if (system_info->host_os_version)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_HOST_OS_VERSION", system_info->host_os_version);
+    if (likely(text))
+        return sqlite3_bind_text(res, position, text, -1, SQLITE_STATIC);
+    if (!can_be_null)
+        return 1;
+    return sqlite3_bind_null(res, position);
+}
 
-    if (system_info->host_os_version_id)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_HOST_OS_VERSION_ID", system_info->host_os_version_id);
+int sql_metadata_cache_stats(int op)
+{
+    int count, dummy;
+    sqlite3_db_status(db_meta, op, &count, &dummy, 0);
+    return count;
+}
 
-    if (system_info->host_os_detection)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_HOST_OS_DETECTION", system_info->host_os_detection);
+#define SQL_FIND_CHART_UUID                                                                                            \
+    "SELECT chart_id FROM chart WHERE host_id = @host AND type=@type AND id=@id AND (name IS NULL OR name=@name) AND chart_id IS NOT NULL;"
 
-    if (system_info->kernel_name)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_KERNEL_NAME", system_info->kernel_name);
+#define SQL_FIND_DIMENSION_UUID \
+    "SELECT dim_id FROM dimension WHERE chart_id=@chart AND id=@id AND name=@name AND LENGTH(dim_id)=16;"
 
-    if (system_info->host_cores)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_CPU_LOGICAL_CPU_COUNT", system_info->host_cores);
 
-    if (system_info->host_cpu_freq)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_CPU_FREQ", system_info->host_cpu_freq);
+//Do a database lookup to find the UUID of a chart
+//If found store it in store_uuid and return 0
+int sql_find_chart_uuid(RRDHOST *host, RRDSET *st, uuid_t *store_uuid)
+{
+    static __thread sqlite3_stmt *res = NULL;
+    int rc;
 
-    if (system_info->host_ram_total)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_TOTAL_RAM", system_info->host_ram_total);
+    const char *name = string2str(st->parts.name);
 
-    if (system_info->host_disk_space)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_TOTAL_DISK_SIZE", system_info->host_disk_space);
+    if (unlikely(!db_meta) && default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
+        return 1;
 
-    if (system_info->kernel_version)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_KERNEL_VERSION", system_info->kernel_version);
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_meta, SQL_FIND_CHART_UUID, &res);
+        if (rc != SQLITE_OK) {
+            error_report("Failed to prepare statement to lookup chart UUID in the database");
+            return 1;
+        }
+    }
 
-    if (system_info->architecture)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_ARCHITECTURE", system_info->architecture);
+    rc = sqlite3_bind_blob(res, 1, &host->host_uuid, sizeof(host->host_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
 
-    if (system_info->virtualization)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_VIRTUALIZATION", system_info->virtualization);
+    rc = sqlite3_bind_text(res, 2,  string2str(st->parts.type), -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
 
-    if (system_info->virt_detection)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_VIRT_DETECTION", system_info->virt_detection);
+    rc = sqlite3_bind_text(res, 3, string2str(st->parts.id), -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
 
-    if (system_info->container)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_CONTAINER", system_info->container);
+    rc = sqlite3_bind_text(res, 4, name && *name ? name : string2str(st->parts.id), -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
 
-    if (system_info->container_detection)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_SYSTEM_CONTAINER_DETECTION", system_info->container_detection);
+    int status = 1;
+    rc = sqlite3_step_monitored(res);
+    if (likely(rc == SQLITE_ROW)) {
+        uuid_copy(*store_uuid, sqlite3_column_blob(res, 0));
+        status = 0;
+    }
 
-    if (system_info->is_k8s_node)
-        sql_store_host_system_info_key_value(host_id, "NETDATA_HOST_IS_K8S_NODE", system_info->is_k8s_node);
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement when searching for a chart UUID, rc = %d", rc);
 
-    return;
-}
+    return status;
 
-static int save_host_label_callback(const char *name, const char *value, RRDLABEL_SRC label_source, void *data)
-{
-    RRDHOST *host = (RRDHOST *)data;
-    sql_store_host_label(&host->host_uuid, (int)label_source & ~(RRDLABEL_FLAG_INTERNAL), name, value);
-    return 0;
+bind_fail:
+    error_report("Failed to bind input parameter to perform chart UUID database lookup, rc = %d", rc);
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement when searching for a chart UUID, rc = %d", rc);
+    return 1;
 }
 
-#define SQL_DELETE_HOST_LABELS  "DELETE FROM host_label WHERE host_id = @uuid;"
-void sql_store_host_labels(RRDHOST *host)
-{
-    int rc = exec_statement_with_uuid(SQL_DELETE_HOST_LABELS, &host->host_uuid);
-    if (rc != SQLITE_OK)
-        error_report("Failed to remove old host labels for host %s", host->hostname);
-
-    rrdlabels_walkthrough_read(host->host_labels, save_host_label_callback, host);
-}
-
-#define SELECT_HOST_LABELS "SELECT label_key, label_value, source_type FROM host_label WHERE host_id = @host_id " \
-    "AND label_key IS NOT NULL AND label_value IS NOT NULL;"
-
-DICTIONARY *sql_load_host_labels(uuid_t *host_id)
+int sql_find_dimension_uuid(RRDSET *st, RRDDIM *rd, uuid_t *store_uuid)
 {
+    static __thread sqlite3_stmt *res = NULL;
     int rc;
+    int status = 1;
 
-    DICTIONARY *labels = NULL;
-    sqlite3_stmt *res = NULL;
+    if (unlikely(!db_meta) && default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
+        return 1;
 
-    rc = sqlite3_prepare_v2(db_meta, SELECT_HOST_LABELS, -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to read host information");
-        return NULL;
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_meta, SQL_FIND_DIMENSION_UUID, &res);
+        if (rc != SQLITE_OK) {
+            error_report("Failed to bind prepare statement to lookup dimension UUID in the database");
+            return 1;
+        }
     }
 
-    rc = sqlite3_bind_blob(res, 1, host_id, sizeof(*host_id), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind host parameter host information");
-        goto skip_loading;
-    }
+    rc = sqlite3_bind_blob(res, 1, st->chart_uuid, sizeof(*st->chart_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
 
-    labels = rrdlabels_create();
+    rc = sqlite3_bind_text(res, 2, rrddim_id(rd), -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
-        rrdlabels_add(
-            labels,
-            (const char *)sqlite3_column_text(res, 0),
-            (const char *)sqlite3_column_text(res, 1),
-            sqlite3_column_int(res, 2));
+    rc = sqlite3_bind_text(res, 3, rrddim_name(rd), -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_step_monitored(res);
+    if (likely(rc == SQLITE_ROW)) {
+        uuid_copy(*store_uuid, *((uuid_t *) sqlite3_column_blob(res, 0)));
+        status = 0;
     }
 
-skip_loading:
-    if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
-        error_report("Failed to finalize the prepared statement when reading host information");
-    return labels;
-}
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement find dimension uuid, rc = %d", rc);
+    return status;
 
-// Utils
-int bind_text_null(sqlite3_stmt *res, int position, const char *text, bool can_be_null)
-{
-    if (likely(text))
-        return sqlite3_bind_text(res, position, text, -1, SQLITE_STATIC);
-    if (!can_be_null)
-        return 1;
-    return sqlite3_bind_null(res, position);
+bind_fail:
+    error_report("Failed to bind input parameter to perform dimension UUID database lookup, rc = %d", rc);
+    return 1;
 }
diff --git a/database/sqlite/sqlite_functions.h b/database/sqlite/sqlite_functions.h
index e6808aa81..5731d5c9e 100644
--- a/database/sqlite/sqlite_functions.h
+++ b/database/sqlite/sqlite_functions.h
@@ -25,29 +25,7 @@ typedef enum db_check_action_type {
 } db_check_action_type_t;
 
 #define SQL_MAX_RETRY (100)
-#define SQLITE_INSERT_DELAY (50)        // Insert delay in case of lock
-
-#define SQL_STORE_HOST "insert or replace into host (host_id,hostname,registry_hostname,update_every,os,timezone,tags, hops) " \
-        "values (?1,?2,?3,?4,?5,?6,?7,?8);"
-
-#define SQL_STORE_CHART "insert or replace into chart (chart_id, host_id, type, id, " \
-    "name, family, context, title, unit, plugin, module, priority, update_every , chart_type , memory_mode , " \
-    "history_entries) values (?1,?2,?3,?4,?5,?6,?7,?8,?9,?10,?11,?12,?13,?14,?15,?16);"
-
-#define SQL_FIND_CHART_UUID                                                                                            \
-    "select chart_id from chart where host_id = @host and type=@type and id=@id and (name is null or name=@name);"
-
-#define SQL_STORE_ACTIVE_CHART                                                                                         \
-    "insert or replace into chart_active (chart_id, date_created) values (@id, unixepoch());"
-
-#define SQL_STORE_DIMENSION                                                                                           \
-    "INSERT OR REPLACE into dimension (dim_id, chart_id, id, name, multiplier, divisor , algorithm) values (?0001,?0002,?0003,?0004,?0005,?0006,?0007);"
-
-#define SQL_FIND_DIMENSION_UUID \
-    "select dim_id from dimension where chart_id=@chart and id=@id and name=@name and length(dim_id)=16;"
-
-#define SQL_STORE_ACTIVE_DIMENSION \
-    "insert or replace into dimension_active (dim_id, date_created) values (@id, unixepoch());"
+#define SQLITE_INSERT_DELAY (10)        // Insert delay in case of lock
 
 #define CHECK_SQLITE_CONNECTION(db_meta)                                                                               \
     if (unlikely(!db_meta)) {                                                                                          \
@@ -58,59 +36,51 @@ typedef enum db_check_action_type {
         return 1;                                                                                                      \
     }
 
-extern int sql_init_database(db_check_action_type_t rebuild, int memory);
-extern void sql_close_database(void);
-extern int bind_text_null(sqlite3_stmt *res, int position, const char *text, bool can_be_null);
-extern int sql_store_host(uuid_t *guid, const char *hostname, const char *registry_hostname, int update_every, const char *os,
-                          const char *timezone, const char *tags, int hops);
-
-extern int sql_store_host_info(RRDHOST *host);
-
-extern int sql_store_chart(
-    uuid_t *chart_uuid, uuid_t *host_uuid, const char *type, const char *id, const char *name, const char *family,
-    const char *context, const char *title, const char *units, const char *plugin, const char *module, long priority,
-    int update_every, int chart_type, int memory_mode, long history_entries);
-extern int sql_store_dimension(uuid_t *dim_uuid, uuid_t *chart_uuid, const char *id, const char *name, collected_number multiplier,
-                               collected_number divisor, int algorithm);
-
-extern int find_dimension_uuid(RRDSET *st, RRDDIM *rd, uuid_t *store_uuid);
-extern void store_active_dimension(uuid_t *dimension_uuid);
-
-extern uuid_t *find_chart_uuid(RRDHOST *host, const char *type, const char *id, const char *name);
-extern uuid_t *create_chart_uuid(RRDSET *st, const char *id, const char *name);
-extern int update_chart_metadata(uuid_t *chart_uuid, RRDSET *st, const char *id, const char *name);
-extern void store_active_chart(uuid_t *dimension_uuid);
-
-extern int find_uuid_type(uuid_t *uuid);
-
-extern void sql_rrdset2json(RRDHOST *host, BUFFER *wb);
-
-extern RRDHOST *sql_create_host_by_uuid(char *guid);
-extern int prepare_statement(sqlite3 *database, char *query, sqlite3_stmt **statement);
-extern int execute_insert(sqlite3_stmt *res);
-extern void db_execute(const char *cmd);
-extern int file_is_migrated(char *path);
-extern void add_migrated_file(char *path, uint64_t file_size);
-extern void db_unlock(void);
-extern void db_lock(void);
-extern void delete_dimension_uuid(uuid_t *dimension_uuid);
-extern void sql_store_chart_label(uuid_t *chart_uuid, int source_type, char *label, char *value);
-extern void sql_build_context_param_list(ONEWAYALLOC  *owa, struct context_param **param_list, RRDHOST *host, char *context, char *chart);
-extern void store_claim_id(uuid_t *host_id, uuid_t *claim_id);
-extern int update_node_id(uuid_t *host_id, uuid_t *node_id);
-extern int get_node_id(uuid_t *host_id, uuid_t *node_id);
-extern int get_host_id(uuid_t *node_id, uuid_t *host_id);
-extern void invalidate_node_instances(uuid_t *host_id, uuid_t *claim_id);
-extern struct node_instance_list *get_node_list(void);
-extern void sql_load_node_id(RRDHOST *host);
-extern void compute_chart_hash(RRDSET *st);
-extern int sql_set_dimension_option(uuid_t *dim_uuid, char *option);
-char *get_hostname_by_node_id(char *node_id);
-void free_temporary_host(RRDHOST *host);
+SQLITE_API int sqlite3_step_monitored(sqlite3_stmt *stmt);
+SQLITE_API int sqlite3_exec_monitored(
+    sqlite3 *db,                               /* An open database */
+    const char *sql,                           /* SQL to be evaluated */
+    int (*callback)(void*,int,char**,char**),  /* Callback function */
+    void *data,                                /* 1st argument to callback */
+    char **errmsg                              /* Error msg written here */
+    );
+
+// Initialization and shutdown
 int init_database_batch(sqlite3 *database, int rebuild, int init_type, const char *batch[]);
-void migrate_localhost(uuid_t *host_uuid);
-extern void sql_store_host_system_info(uuid_t *host_id, const struct rrdhost_system_info *system_info);
-extern void sql_build_host_system_info(uuid_t *host_id, struct rrdhost_system_info *system_info);
-void sql_store_host_labels(RRDHOST *host);
+int sql_init_database(db_check_action_type_t rebuild, int memory);
+void sql_close_database(void);
+
+// Helpers
+int bind_text_null(sqlite3_stmt *res, int position, const char *text, bool can_be_null);
+int prepare_statement(sqlite3 *database, const char *query, sqlite3_stmt **statement);
+int execute_insert(sqlite3_stmt *res);
+int file_is_migrated(char *path);
+int exec_statement_with_uuid(const char *sql, uuid_t *uuid);
+void add_migrated_file(char *path, uint64_t file_size);
+void db_execute(const char *cmd);
+
+// Look up functions
+int get_node_id(uuid_t *host_id, uuid_t *node_id);
+int get_host_id(uuid_t *node_id, uuid_t *host_id);
+struct node_instance_list *get_node_list(void);
+void sql_load_node_id(RRDHOST *host);
+char *get_hostname_by_node_id(char *node_id);
+int sql_find_chart_uuid(RRDHOST *host, RRDSET *st, uuid_t *store_uuid);
+int sql_find_dimension_uuid(RRDSET *st, RRDDIM *rd, uuid_t *store_uuid);
+
+// Help build archived hosts in memory when agent starts
+void sql_build_host_system_info(uuid_t *host_id, struct rrdhost_system_info *system_info);
 DICTIONARY *sql_load_host_labels(uuid_t *host_id);
+
+// For queries: To be removed when context queries are implemented
+void sql_rrdset2json(RRDHOST *host, BUFFER *wb);
+
+// TODO: move to metadata
+int update_node_id(uuid_t *host_id, uuid_t *node_id);
+
+void invalidate_node_instances(uuid_t *host_id, uuid_t *claim_id);
+
+// Provide statistics
+int sql_metadata_cache_stats(int op);
+
 #endif //NETDATA_SQLITE_FUNCTIONS_H
diff --git a/database/sqlite/sqlite_health.c b/database/sqlite/sqlite_health.c
index 8e59cad1e..c189305b8 100644
--- a/database/sqlite/sqlite_health.c
+++ b/database/sqlite/sqlite_health.c
@@ -4,6 +4,7 @@
 #include "sqlite_functions.h"
 
 #define MAX_HEALTH_SQL_SIZE 2048
+#define sqlite3_bind_string_or_null(res,key,param) ((key) ? sqlite3_bind_text(res, param, string2str(key), -1, SQLITE_STATIC) : sqlite3_bind_null(res, param))
 
 /* Health related SQL queries
    Creates a health log table in sqlite, one per host guid
@@ -15,7 +16,7 @@ int sql_create_health_log_table(RRDHOST *host) {
 
     if (unlikely(!db_meta)) {
         if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("HEALTH [%s]: Database has not been initialized", host->hostname);
+            error_report("HEALTH [%s]: Database has not been initialized", rrdhost_hostname(host));
         return 1;
     }
 
@@ -24,9 +25,9 @@ int sql_create_health_log_table(RRDHOST *host) {
 
     snprintfz(command, MAX_HEALTH_SQL_SIZE, SQL_CREATE_HEALTH_LOG_TABLE(uuid_str));
 
-    rc = sqlite3_exec(db_meta, command, 0, 0, &err_msg);
+    rc = sqlite3_exec_monitored(db_meta, command, 0, 0, &err_msg);
     if (rc != SQLITE_OK) {
-        error_report("HEALTH [%s]: SQLite error during creation of health log table, rc = %d (%s)", host->hostname, rc, err_msg);
+        error_report("HEALTH [%s]: SQLite error during creation of health log table, rc = %d (%s)", rrdhost_hostname(host), rc, err_msg);
         sqlite3_free(err_msg);
         return 1;
     }
@@ -49,7 +50,7 @@ void sql_health_alarm_log_update(RRDHOST *host, ALARM_ENTRY *ae) {
 
     if (unlikely(!db_meta)) {
         if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("HEALTH [%s]: Database has not been initialized", host->hostname);
+            error_report("HEALTH [%s]: Database has not been initialized", rrdhost_hostname(host));
         return;
     }
 
@@ -60,7 +61,7 @@ void sql_health_alarm_log_update(RRDHOST *host, ALARM_ENTRY *ae) {
 
     rc = sqlite3_prepare_v2(db_meta, command, -1, &res, 0);
     if (unlikely(rc != SQLITE_OK)) {
-        error_report("HEALTH [%s]: Failed to prepare statement for SQL_UPDATE_HEALTH_LOG", host->hostname);
+        error_report("HEALTH [%s]: Failed to prepare statement for SQL_UPDATE_HEALTH_LOG", rrdhost_hostname(host));
         return;
     }
 
@@ -96,12 +97,12 @@ void sql_health_alarm_log_update(RRDHOST *host, ALARM_ENTRY *ae) {
 
     rc = execute_insert(res);
     if (unlikely(rc != SQLITE_DONE)) {
-        error_report("HEALTH [%s]: Failed to update health log, rc = %d", host->hostname, rc);
+        error_report("HEALTH [%s]: Failed to update health log, rc = %d", rrdhost_hostname(host), rc);
     }
 
     failed:
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
-        error_report("HEALTH [%s]: Failed to finalize the prepared statement for updating health log.", host->hostname);
+        error_report("HEALTH [%s]: Failed to finalize the prepared statement for updating health log.", rrdhost_hostname(host));
 
     return;
 }
@@ -122,7 +123,7 @@ void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae) {
 
     if (unlikely(!db_meta)) {
         if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("HEALTH [%s]: Database has not been initialized", host->hostname);
+            error_report("HEALTH [%s]: Database has not been initialized", rrdhost_hostname(host));
         return;
     }
 
@@ -133,11 +134,11 @@ void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae) {
 
     rc = sqlite3_prepare_v2(db_meta, command, -1, &res, 0);
     if (unlikely(rc != SQLITE_OK)) {
-        error_report("HEALTH [%s]: Failed to prepare statement for SQL_INSERT_HEALTH_LOG", host->hostname);
+        error_report("HEALTH [%s]: Failed to prepare statement for SQL_INSERT_HEALTH_LOG", rrdhost_hostname(host));
         return;
     }
 
-    rc = sqlite3_bind_text(res, 1, host->hostname, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, 1, rrdhost_hostname(host), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind hostname parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
@@ -215,49 +216,49 @@ void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae) {
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 14, ae->name, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->name, 14);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind name parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 15, ae->chart, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->chart, 15);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind chart parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 16, ae->family, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->family, 16);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind family parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 17, ae->exec, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->exec, 17);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind exec parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 18, ae->recipient, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->recipient, 18);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind recipient parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 19, ae->source, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->source, 19);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind source parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 20, ae->units, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->units, 20);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind host_id parameter to store node instance information");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 21, ae->info, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->info, 21);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind info parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
@@ -305,25 +306,25 @@ void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae) {
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 29, ae->classification, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->classification, 29);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind classification parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 30, ae->component, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->component, 30);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind component parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 31, ae->type, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->type, 31);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind type parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
     }
 
-    rc = sqlite3_bind_text(res, 32, ae->chart_context, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, ae->chart_context, 32);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to bind chart_context parameter for SQL_INSERT_HEALTH_LOG");
         goto failed;
@@ -331,7 +332,7 @@ void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae) {
 
     rc = execute_insert(res);
     if (unlikely(rc != SQLITE_DONE)) {
-        error_report("HEALTH [%s]: Failed to execute SQL_INSERT_HEALTH_LOG, rc = %d", host->hostname, rc);
+        error_report("HEALTH [%s]: Failed to execute SQL_INSERT_HEALTH_LOG, rc = %d", rrdhost_hostname(host), rc);
         goto failed;
     }
 
@@ -340,7 +341,7 @@ void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae) {
 
     failed:
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
-        error_report("HEALTH [%s]: Failed to finalize the prepared statement for inserting to health log.", host->hostname);
+        error_report("HEALTH [%s]: Failed to finalize the prepared statement for inserting to health log.", rrdhost_hostname(host));
 
     return;
 }
@@ -381,7 +382,7 @@ void sql_health_alarm_log_cleanup(RRDHOST *host) {
     char uuid_str[GUID_LEN + 1];
     uuid_unparse_lower_fix(&host->host_uuid, uuid_str);
 
-    snprintfz(command, MAX_HEALTH_SQL_SIZE, SQL_CLEANUP_HEALTH_LOG(uuid_str, uuid_str, host->health_log_entries_written - rotate_every));
+    snprintfz(command, MAX_HEALTH_SQL_SIZE, SQL_CLEANUP_HEALTH_LOG(uuid_str, uuid_str, (unsigned long int) (host->health_log_entries_written - rotate_every)));
 
     rc = sqlite3_prepare_v2(db_meta, command, -1, &res, 0);
     if (unlikely(rc != SQLITE_OK)) {
@@ -389,7 +390,7 @@ void sql_health_alarm_log_cleanup(RRDHOST *host) {
         return;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
     if (unlikely(rc != SQLITE_DONE))
         error_report("Failed to cleanup health log table, rc = %d", rc);
 
@@ -428,7 +429,7 @@ void sql_health_alarm_log_count(RRDHOST *host) {
         return;
     }
 
-    rc = sqlite3_step(res);
+    rc = sqlite3_step_monitored(res);
     if (likely(rc == SQLITE_ROW))
         host->health_log_entries_written = (size_t) sqlite3_column_int64(res, 0);
 
@@ -436,7 +437,7 @@ void sql_health_alarm_log_count(RRDHOST *host) {
     if (unlikely(rc != SQLITE_OK))
         error_report("Failed to finalize the prepared statement to count health log entries from db");
 
-    info("HEALTH [%s]: Table health_log_%s, contains %lu entries.", host->hostname, uuid_str, host->health_log_entries_written);
+    info("HEALTH [%s]: Table health_log_%s, contains %lu entries.", rrdhost_hostname(host), uuid_str, (unsigned long int) host->health_log_entries_written);
 }
 
 #define SQL_INJECT_REMOVED(guid, guid2) "insert into health_log_%s (hostname, unique_id, alarm_id, alarm_event_id, config_hash_id, updated_by_id, updates_id, when_key, duration, non_clear_duration, flags, exec_run_timestamp, " \
@@ -556,7 +557,7 @@ uint32_t sql_get_max_unique_id (char *uuid_str)
         return 0;
     }
 
-     while (sqlite3_step(res) == SQLITE_ROW) {
+     while (sqlite3_step_monitored(res) == SQLITE_ROW) {
          max_unique_id = (uint32_t) sqlite3_column_int64(res, 0);
      }
 
@@ -584,7 +585,7 @@ void sql_check_removed_alerts_state(char *uuid_str)
         return;
     }
 
-     while (sqlite3_step(res) == SQLITE_ROW) {
+     while (sqlite3_step_monitored(res) == SQLITE_ROW) {
          status  = (RRDCALC_STATUS) sqlite3_column_int(res, 0);
          unique_id = (uint32_t) sqlite3_column_int64(res, 1);
          alarm_id = (uint32_t) sqlite3_column_int64(res, 2);
@@ -607,7 +608,7 @@ void sql_check_removed_alerts_state(char *uuid_str)
 #define SQL_LOAD_HEALTH_LOG(guid,limit) "SELECT hostname, unique_id, alarm_id, alarm_event_id, config_hash_id, updated_by_id, updates_id, when_key, duration, non_clear_duration, flags, exec_run_timestamp, delay_up_to_timestamp, name, chart, family, exec, recipient, source, units, info, exec_code, new_status, old_status, delay, new_value, old_value, last_repeat, class, component, type, chart_context FROM (SELECT hostname, unique_id, alarm_id, alarm_event_id, config_hash_id, updated_by_id, updates_id, when_key, duration, non_clear_duration, flags, exec_run_timestamp, delay_up_to_timestamp, name, chart, family, exec, recipient, source, units, info, exec_code, new_status, old_status, delay, new_value, old_value, last_repeat, class, component, type, chart_context FROM health_log_%s order by unique_id desc limit %u) order by unique_id asc;", guid, limit
 void sql_health_alarm_log_load(RRDHOST *host) {
     sqlite3_stmt *res = NULL;
-    int rc;
+    int ret;
     ssize_t errored = 0, loaded = 0;
     char command[MAX_HEALTH_SQL_SIZE + 1];
 
@@ -615,7 +616,7 @@ void sql_health_alarm_log_load(RRDHOST *host) {
 
     if (unlikely(!db_meta)) {
         if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("HEALTH [%s]: Database has not been initialized", host->hostname);
+            error_report("HEALTH [%s]: Database has not been initialized", rrdhost_hostname(host));
         return;
     }
 
@@ -626,47 +627,55 @@ void sql_health_alarm_log_load(RRDHOST *host) {
 
     snprintfz(command, MAX_HEALTH_SQL_SIZE, SQL_LOAD_HEALTH_LOG(uuid_str, host->health_log.max));
 
-    rc = sqlite3_prepare_v2(db_meta, command, -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("HEALTH [%s]: Failed to prepare sql statement to load health log.", host->hostname);
+    ret = sqlite3_prepare_v2(db_meta, command, -1, &res, 0);
+    if (unlikely(ret != SQLITE_OK)) {
+        error_report("HEALTH [%s]: Failed to prepare sql statement to load health log.", rrdhost_hostname(host));
         return;
     }
 
+    DICTIONARY *all_rrdcalcs = dictionary_create(
+        DICT_OPTION_NAME_LINK_DONT_CLONE | DICT_OPTION_VALUE_LINK_DONT_CLONE | DICT_OPTION_DONT_OVERWRITE_VALUE);
+    RRDCALC *rc;
+    foreach_rrdcalc_in_rrdhost_read(host, rc) {
+        dictionary_set(all_rrdcalcs, rrdcalc_name(rc), rc, sizeof(*rc));
+    }
+    foreach_rrdcalc_in_rrdhost_done(rc);
+
     netdata_rwlock_rdlock(&host->health_log.alarm_log_rwlock);
 
-    while (sqlite3_step(res) == SQLITE_ROW) {
+    while (sqlite3_step_monitored(res) == SQLITE_ROW) {
         ALARM_ENTRY *ae = NULL;
 
         // check that we have valid ids
         uint32_t unique_id = (uint32_t) sqlite3_column_int64(res, 1);
         if(!unique_id) {
-            error_report("HEALTH [%s]: Got invalid unique id. Ignoring it.", host->hostname);
+            error_report("HEALTH [%s]: Got invalid unique id. Ignoring it.", rrdhost_hostname(host));
             errored++;
             continue;
         }
 
         uint32_t alarm_id = (uint32_t) sqlite3_column_int64(res, 2);
         if(!alarm_id) {
-            error_report("HEALTH [%s]: Got invalid alarm id. Ignoring it.", host->hostname);
+            error_report("HEALTH [%s]: Got invalid alarm id. Ignoring it.", rrdhost_hostname(host));
             errored++;
             continue;
         }
 
         //need name, chart and family
         if (sqlite3_column_type(res, 13) == SQLITE_NULL) {
-            error_report("HEALTH [%s]: Got null name field. Ignoring it.", host->hostname);
+            error_report("HEALTH [%s]: Got null name field. Ignoring it.", rrdhost_hostname(host));
             errored++;
             continue;
         }
 
         if (sqlite3_column_type(res, 14) == SQLITE_NULL) {
-            error_report("HEALTH [%s]: Got null chart field. Ignoring it.", host->hostname);
+            error_report("HEALTH [%s]: Got null chart field. Ignoring it.", rrdhost_hostname(host));
             errored++;
             continue;
         }
 
         if (sqlite3_column_type(res, 15) == SQLITE_NULL) {
-            error_report("HEALTH [%s]: Got null family field. Ignoring it.", host->hostname);
+            error_report("HEALTH [%s]: Got null family field. Ignoring it.", rrdhost_hostname(host));
             errored++;
             continue;
         }
@@ -675,18 +684,7 @@ void sql_health_alarm_log_load(RRDHOST *host) {
         time_t last_repeat = 0;
         last_repeat = (time_t)sqlite3_column_int64(res, 27);
 
-        RRDCALC *rc = alarm_max_last_repeat(host, (char *) sqlite3_column_text(res, 14), simple_hash((char *) sqlite3_column_text(res, 14)));
-        if (!rc) {
-            for(rc = host->alarms; rc ; rc = rc->next) {
-                RRDCALC *rdcmp  = (RRDCALC *) avl_insert_lock(&(host)->alarms_idx_name, (avl_t *)rc);
-                if(rdcmp != rc) {
-                    error("Cannot insert the alarm index ID using log %s", rc->name);
-                }
-            }
-
-            rc = alarm_max_last_repeat(host, (char *) sqlite3_column_text(res, 14), simple_hash((char *) sqlite3_column_text(res, 14)));
-        }
-
+        rc = dictionary_get(all_rrdcalcs, (char *) sqlite3_column_text(res, 14));
         if(unlikely(rc)) {
             if (rrdcalc_isrepeating(rc)) {
                 rc->last_repeat = last_repeat;
@@ -719,36 +717,32 @@ void sql_health_alarm_log_load(RRDHOST *host) {
         ae->exec_run_timestamp = (time_t) sqlite3_column_int64(res, 11);
         ae->delay_up_to_timestamp = (time_t) sqlite3_column_int64(res, 12);
 
-        ae->name = strdupz((char *) sqlite3_column_text(res, 13));
-        ae->hash_name = simple_hash(ae->name);
-
-        ae->chart = strdupz((char *) sqlite3_column_text(res, 14));
-        ae->hash_chart = simple_hash(ae->chart);
-
-        ae->family = strdupz((char *) sqlite3_column_text(res, 15));
+        ae->name   = string_strdupz((char *) sqlite3_column_text(res, 13));
+        ae->chart  = string_strdupz((char *) sqlite3_column_text(res, 14));
+        ae->family = string_strdupz((char *) sqlite3_column_text(res, 15));
 
         if (sqlite3_column_type(res, 16) != SQLITE_NULL)
-            ae->exec = strdupz((char *) sqlite3_column_text(res, 16));
+            ae->exec = string_strdupz((char *) sqlite3_column_text(res, 16));
         else
             ae->exec = NULL;
 
         if (sqlite3_column_type(res, 17) != SQLITE_NULL)
-            ae->recipient = strdupz((char *) sqlite3_column_text(res, 17));
+            ae->recipient = string_strdupz((char *) sqlite3_column_text(res, 17));
         else
             ae->recipient = NULL;
 
         if (sqlite3_column_type(res, 18) != SQLITE_NULL)
-            ae->source = strdupz((char *) sqlite3_column_text(res, 18));
+            ae->source = string_strdupz((char *) sqlite3_column_text(res, 18));
         else
             ae->source = NULL;
 
         if (sqlite3_column_type(res, 19) != SQLITE_NULL)
-            ae->units = strdupz((char *) sqlite3_column_text(res, 19));
+            ae->units = string_strdupz((char *) sqlite3_column_text(res, 19));
         else
             ae->units = NULL;
 
         if (sqlite3_column_type(res, 20) != SQLITE_NULL)
-            ae->info = strdupz((char *) sqlite3_column_text(res, 20));
+            ae->info = string_strdupz((char *) sqlite3_column_text(res, 20));
         else
             ae->info = NULL;
 
@@ -763,30 +757,30 @@ void sql_health_alarm_log_load(RRDHOST *host) {
         ae->last_repeat = last_repeat;
 
         if (sqlite3_column_type(res, 28) != SQLITE_NULL)
-            ae->classification = strdupz((char *) sqlite3_column_text(res, 28));
+            ae->classification = string_strdupz((char *) sqlite3_column_text(res, 28));
         else
             ae->classification = NULL;
 
         if (sqlite3_column_type(res, 29) != SQLITE_NULL)
-            ae->component = strdupz((char *) sqlite3_column_text(res, 29));
+            ae->component = string_strdupz((char *) sqlite3_column_text(res, 29));
         else
             ae->component = NULL;
 
         if (sqlite3_column_type(res, 30) != SQLITE_NULL)
-            ae->type = strdupz((char *) sqlite3_column_text(res, 30));
+            ae->type = string_strdupz((char *) sqlite3_column_text(res, 30));
         else
             ae->type = NULL;
 
         if (sqlite3_column_type(res, 31) != SQLITE_NULL)
-            ae->chart_context = strdupz((char *) sqlite3_column_text(res, 31));
+            ae->chart_context = string_strdupz((char *) sqlite3_column_text(res, 31));
         else
             ae->chart_context = NULL;
 
         char value_string[100 + 1];
-        freez(ae->old_value_string);
-        freez(ae->new_value_string);
-        ae->old_value_string = strdupz(format_value_and_unit(value_string, 100, ae->old_value, ae->units, -1));
-        ae->new_value_string = strdupz(format_value_and_unit(value_string, 100, ae->new_value, ae->units, -1));
+        string_freez(ae->old_value_string);
+        string_freez(ae->new_value_string);
+        ae->old_value_string = string_strdupz(format_value_and_unit(value_string, 100, ae->old_value, ae_units(ae), -1));
+        ae->new_value_string = string_strdupz(format_value_and_unit(value_string, 100, ae->new_value, ae_units(ae), -1));
 
         ae->next = host->health_log.alarms;
         host->health_log.alarms = ae;
@@ -802,6 +796,9 @@ void sql_health_alarm_log_load(RRDHOST *host) {
 
     netdata_rwlock_unlock(&host->health_log.alarm_log_rwlock);
 
+    dictionary_destroy(all_rrdcalcs);
+    all_rrdcalcs = NULL;
+
     if(!host->health_max_unique_id) host->health_max_unique_id = (uint32_t)now_realtime_sec();
     if(!host->health_max_alarm_id)  host->health_max_alarm_id  = (uint32_t)now_realtime_sec();
 
@@ -809,10 +806,10 @@ void sql_health_alarm_log_load(RRDHOST *host) {
     if (unlikely(!host->health_log.next_alarm_id || host->health_log.next_alarm_id <= host->health_max_alarm_id))
         host->health_log.next_alarm_id = host->health_max_alarm_id + 1;
 
-    info("HEALTH [%s]: Table health_log_%s, loaded %zd alarm entries, errors in %zd entries.", host->hostname, uuid_str, loaded, errored);
+    log_health("[%s]: Table health_log_%s, loaded %zd alarm entries, errors in %zd entries.", rrdhost_hostname(host), uuid_str, loaded, errored);
 
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
+    ret = sqlite3_finalize(res);
+    if (unlikely(ret != SQLITE_OK))
         error_report("Failed to finalize the health log read statement");
 
     sql_health_alarm_log_count(host);
@@ -849,159 +846,153 @@ int sql_store_alert_config_hash(uuid_t *hash_id, struct alert_config *cfg)
     }
 
     param++;
-    rc = sqlite3_bind_blob(res, 1, hash_id, sizeof(*hash_id), SQLITE_STATIC);
+    rc = sqlite3_bind_blob(res, param, hash_id, sizeof(*hash_id), SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    if (cfg->alarm && *cfg->alarm)
-        rc = sqlite3_bind_text(res, 2, cfg->alarm, -1, SQLITE_STATIC);
-    else
-        rc = sqlite3_bind_null(res, 2);
+    rc = sqlite3_bind_string_or_null(res, cfg->alarm, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    if (cfg->template_key && *cfg->template_key)
-        rc = sqlite3_bind_text(res, 3, cfg->template_key, -1, SQLITE_STATIC);
-    else
-        rc = sqlite3_bind_null(res, 3);
+    rc = sqlite3_bind_string_or_null(res, cfg->template_key, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 4, cfg->on, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->on, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 5, cfg->classification, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->classification, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 6, cfg->component, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->component, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 7, cfg->type, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->type, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 8, cfg->os, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->os, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 9, cfg->host, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->host, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 10, cfg->lookup, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->lookup, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 11, cfg->every, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->every, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 12, cfg->units, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->units, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 13, cfg->calc, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->calc, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 14, cfg->families, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->families, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 15, cfg->plugin, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->plugin, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 16, cfg->module, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->module, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 17, cfg->charts, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->charts, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 18, cfg->green, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->green, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 19, cfg->red, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->red, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 20, cfg->warn, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->warn, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 21, cfg->crit, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->crit, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 22, cfg->exec, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->exec, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 23, cfg->to, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->to, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 24, cfg->info, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->info, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 25, cfg->delay, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->delay, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 26, cfg->options, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->options, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 27, cfg->repeat, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->repeat, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     param++;
-    rc = sqlite3_bind_text(res, 28, cfg->host_labels, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_string_or_null(res, cfg->host_labels, param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
     if (cfg->p_db_lookup_after) {
         param++;
-        rc = sqlite3_bind_text(res, 29, cfg->p_db_lookup_dimensions, -1, SQLITE_STATIC);
+        rc = sqlite3_bind_string_or_null(res, cfg->p_db_lookup_dimensions, param);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
 
         param++;
-        rc = sqlite3_bind_text(res, 30, cfg->p_db_lookup_method, -1, SQLITE_STATIC);
+        rc = sqlite3_bind_string_or_null(res, cfg->p_db_lookup_method, param);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
 
@@ -1071,7 +1062,7 @@ int sql_store_alert_config_hash(uuid_t *hash_id, struct alert_config *cfg)
   skip hash calculations
 */
 #if !defined DISABLE_CLOUD && defined ENABLE_HTTPS
-#define DIGEST_ALERT_CONFIG_VAL(v) ((v) ? EVP_DigestUpdate(evpctx, (v), strlen((v))) : EVP_DigestUpdate(evpctx, "", 1))
+#define DIGEST_ALERT_CONFIG_VAL(v) ((v) ? EVP_DigestUpdate(evpctx, (string2str(v)), string_strlen((v))) : EVP_DigestUpdate(evpctx, "", 1))
 #endif
 int alert_hash_and_store_config(
     uuid_t hash_id,
diff --git a/database/sqlite/sqlite_health.h b/database/sqlite/sqlite_health.h
index ef837894a..87060dacc 100644
--- a/database/sqlite/sqlite_health.h
+++ b/database/sqlite/sqlite_health.h
@@ -6,12 +6,12 @@
 #include "sqlite3.h"
 
 extern sqlite3 *db_meta;
-extern void sql_health_alarm_log_load(RRDHOST *host);
-extern int sql_create_health_log_table(RRDHOST *host);
-extern void sql_health_alarm_log_update(RRDHOST *host, ALARM_ENTRY *ae);
-extern void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae);
-extern void sql_health_alarm_log_save(RRDHOST *host, ALARM_ENTRY *ae);
-extern void sql_health_alarm_log_cleanup(RRDHOST *host);
-extern int alert_hash_and_store_config(uuid_t hash_id, struct alert_config *cfg, int store_hash);
-extern void sql_aclk_alert_clean_dead_entries(RRDHOST *host);
+void sql_health_alarm_log_load(RRDHOST *host);
+int sql_create_health_log_table(RRDHOST *host);
+void sql_health_alarm_log_update(RRDHOST *host, ALARM_ENTRY *ae);
+void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae);
+void sql_health_alarm_log_save(RRDHOST *host, ALARM_ENTRY *ae);
+void sql_health_alarm_log_cleanup(RRDHOST *host);
+int alert_hash_and_store_config(uuid_t hash_id, struct alert_config *cfg, int store_hash);
+void sql_aclk_alert_clean_dead_entries(RRDHOST *host);
 #endif //NETDATA_SQLITE_HEALTH_H
diff --git a/database/sqlite/sqlite_metadata.c b/database/sqlite/sqlite_metadata.c
new file mode 100644
index 000000000..4eb212152
--- /dev/null
+++ b/database/sqlite/sqlite_metadata.c
@@ -0,0 +1,1580 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "sqlite_metadata.h"
+
+// SQL statements
+
+#define SQL_STORE_CLAIM_ID  "insert into node_instance " \
+    "(host_id, claim_id, date_created) values (@host_id, @claim_id, unixepoch()) " \
+    "on conflict(host_id) do update set claim_id = excluded.claim_id;"
+
+#define SQL_DELETE_HOST_LABELS  "DELETE FROM host_label WHERE host_id = @uuid;"
+
+#define STORE_HOST_LABEL                                                                                               \
+    "INSERT OR REPLACE INTO host_label (host_id, source_type, label_key, label_value, date_created) VALUES "
+
+#define STORE_CHART_LABEL                                                                                              \
+    "INSERT OR REPLACE INTO chart_label (chart_id, source_type, label_key, label_value, date_created) VALUES "
+
+#define STORE_HOST_OR_CHART_LABEL_VALUE "(u2h('%s'), %d,'%s','%s', unixepoch())"
+
+#define DELETE_DIMENSION_UUID   "DELETE FROM dimension WHERE dim_id = @uuid;"
+
+#define SQL_STORE_HOST_INFO "INSERT OR REPLACE INTO host " \
+        "(host_id, hostname, registry_hostname, update_every, os, timezone," \
+        "tags, hops, memory_mode, abbrev_timezone, utc_offset, program_name, program_version," \
+        "entries, health_enabled) " \
+        "values (@host_id, @hostname, @registry_hostname, @update_every, @os, @timezone, @tags, @hops, @memory_mode, " \
+        "@abbrev_timezone, @utc_offset, @program_name, @program_version, " \
+        "@entries, @health_enabled);"
+
+#define SQL_STORE_CHART "insert or replace into chart (chart_id, host_id, type, id, " \
+    "name, family, context, title, unit, plugin, module, priority, update_every , chart_type , memory_mode , " \
+    "history_entries) values (?1,?2,?3,?4,?5,?6,?7,?8,?9,?10,?11,?12,?13,?14,?15,?16);"
+
+#define SQL_STORE_DIMENSION "INSERT OR REPLACE INTO dimension (dim_id, chart_id, id, name, multiplier, divisor , algorithm, options) " \
+        "VALUES (@dim_id, @chart_id, @id, @name, @multiplier, @divisor, @algorithm, @options);"
+
+#define SELECT_DIMENSION_LIST "SELECT dim_id, rowid FROM dimension WHERE rowid > @row_id"
+
+#define STORE_HOST_INFO "INSERT OR REPLACE INTO host_info (host_id, system_key, system_value, date_created) VALUES "
+#define STORE_HOST_INFO_VALUES "(u2h('%s'), '%s','%s', unixepoch())"
+
+#define MIGRATE_LOCALHOST_TO_NEW_MACHINE_GUID                                                                          \
+    "UPDATE chart SET host_id = @host_id WHERE host_id in (SELECT host_id FROM host where host_id <> @host_id and hops = 0);"
+#define DELETE_NON_EXISTING_LOCALHOST "DELETE FROM host WHERE hops = 0 AND host_id <> @host_id;"
+#define DELETE_MISSING_NODE_INSTANCES "DELETE FROM node_instance WHERE host_id NOT IN (SELECT host_id FROM host);"
+
+#define METADATA_CMD_Q_MAX_SIZE (1024)              // Max queue size; callers will block until there is room
+#define METADATA_MAINTENANCE_FIRST_CHECK (1800)     // Maintenance first run after agent startup in seconds
+#define METADATA_MAINTENANCE_RETRY (60)             // Retry run if already running or last run did actual work
+#define METADATA_MAINTENANCE_INTERVAL (3600)        // Repeat maintenance after latest successful
+
+#define METADATA_HOST_CHECK_FIRST_CHECK (5)         // First check for pending metadata
+#define METADATA_HOST_CHECK_INTERVAL (30)           // Repeat check for pending metadata
+#define METADATA_HOST_CHECK_IMMEDIATE (5)           // Repeat immediate run because we have more metadata to write
+
+#define MAX_METADATA_CLEANUP (500)                  // Maximum metadata write operations (e.g  deletes before retrying)
+#define METADATA_MAX_BATCH_SIZE (512)               // Maximum commands to execute before running the event loop
+#define METADATA_MAX_TRANSACTION_BATCH (128)        // Maximum commands to add in a transaction
+
+enum metadata_opcode {
+    METADATA_DATABASE_NOOP = 0,
+    METADATA_DATABASE_TIMER,
+    METADATA_ADD_CHART,
+    METADATA_ADD_CHART_LABEL,
+    METADATA_ADD_DIMENSION,
+    METADATA_DEL_DIMENSION,
+    METADATA_ADD_DIMENSION_OPTION,
+    METADATA_ADD_HOST_SYSTEM_INFO,
+    METADATA_ADD_HOST_INFO,
+    METADATA_STORE_CLAIM_ID,
+    METADATA_STORE_HOST_LABELS,
+    METADATA_STORE_BUFFER,
+
+    METADATA_SKIP_TRANSACTION,                      // Dummy -- OPCODES less than this one can be in a tranasction
+
+    METADATA_SCAN_HOSTS,
+    METADATA_MAINTENANCE,
+    METADATA_SYNC_SHUTDOWN,
+    METADATA_UNITTEST,
+    // leave this last
+    // we need it to check for worker utilization
+    METADATA_MAX_ENUMERATIONS_DEFINED
+};
+
+#define MAX_PARAM_LIST  (2)
+struct metadata_cmd {
+    enum metadata_opcode opcode;
+    struct completion *completion;
+    const void *param[MAX_PARAM_LIST];
+};
+
+struct metadata_database_cmdqueue {
+    unsigned head, tail;
+    struct metadata_cmd cmd_array[METADATA_CMD_Q_MAX_SIZE];
+};
+
+typedef enum {
+    METADATA_FLAG_CLEANUP           = (1 << 0), // Cleanup is running
+    METADATA_FLAG_SCANNING_HOSTS    = (1 << 1), // Scanning of hosts in worker thread
+    METADATA_FLAG_SHUTDOWN          = (1 << 2), // Shutting down
+} METADATA_FLAG;
+
+#define METADATA_WORKER_BUSY    (METADATA_FLAG_CLEANUP | METADATA_FLAG_SCANNING_HOSTS)
+
+struct metadata_wc {
+    uv_thread_t thread;
+    time_t check_metadata_after;
+    time_t check_hosts_after;
+    volatile unsigned queue_size;
+    uv_loop_t *loop;
+    uv_async_t async;
+    METADATA_FLAG flags;
+    uint64_t row_id;
+    uv_timer_t timer_req;
+    struct completion init_complete;
+    /* FIFO command queue */
+    uv_mutex_t cmd_mutex;
+    uv_cond_t cmd_cond;
+    struct metadata_database_cmdqueue cmd_queue;
+};
+
+#define metadata_flag_check(target_flags, flag) (__atomic_load_n(&((target_flags)->flags), __ATOMIC_SEQ_CST) & (flag))
+#define metadata_flag_set(target_flags, flag)   __atomic_or_fetch(&((target_flags)->flags), (flag), __ATOMIC_SEQ_CST)
+#define metadata_flag_clear(target_flags, flag) __atomic_and_fetch(&((target_flags)->flags), ~(flag), __ATOMIC_SEQ_CST)
+
+//
+// For unittest
+//
+struct thread_unittest {
+    int join;
+    unsigned added;
+    unsigned processed;
+    unsigned *done;
+};
+
+
+// Metadata functions
+
+struct query_build {
+    BUFFER *sql;
+    int count;
+    char uuid_str[UUID_STR_LEN];
+};
+
+static int host_label_store_to_sql_callback(const char *name, const char *value, RRDLABEL_SRC ls, void *data) {
+    struct query_build *lb = data;
+    if (unlikely(!lb->count))
+        buffer_sprintf(lb->sql, STORE_HOST_LABEL);
+    else
+        buffer_strcat(lb->sql, ", ");
+    buffer_sprintf(lb->sql, STORE_HOST_OR_CHART_LABEL_VALUE, lb->uuid_str, (int)ls & ~(RRDLABEL_FLAG_INTERNAL), name, value);
+    lb->count++;
+    return 1;
+}
+
+static int chart_label_store_to_sql_callback(const char *name, const char *value, RRDLABEL_SRC ls, void *data) {
+    struct query_build *lb = data;
+    if (unlikely(!lb->count))
+        buffer_sprintf(lb->sql, STORE_CHART_LABEL);
+    else
+        buffer_strcat(lb->sql, ", ");
+    buffer_sprintf(lb->sql, STORE_HOST_OR_CHART_LABEL_VALUE, lb->uuid_str, ls, name, value);
+    lb->count++;
+    return 1;
+}
+
+static void check_and_update_chart_labels(RRDSET *st, BUFFER *work_buffer)
+{
+    size_t old_version = st->rrdlabels_last_saved_version;
+    size_t new_version = dictionary_version(st->rrdlabels);
+
+    if(new_version != old_version) {
+        buffer_flush(work_buffer);
+        struct query_build tmp = {.sql = work_buffer, .count = 0};
+        uuid_unparse_lower(st->chart_uuid, tmp.uuid_str);
+        rrdlabels_walkthrough_read(st->rrdlabels, chart_label_store_to_sql_callback, &tmp);
+        st->rrdlabels_last_saved_version = new_version;
+        db_execute(buffer_tostring(work_buffer));
+    }
+}
+
+// Migrate all hosts with hops zero to this host_uuid
+void migrate_localhost(uuid_t *host_uuid)
+{
+    int rc;
+
+    rc = exec_statement_with_uuid(MIGRATE_LOCALHOST_TO_NEW_MACHINE_GUID, host_uuid);
+    if (!rc)
+        rc = exec_statement_with_uuid(DELETE_NON_EXISTING_LOCALHOST, host_uuid);
+    if (!rc)
+        db_execute(DELETE_MISSING_NODE_INSTANCES);
+
+}
+
+static void store_claim_id(uuid_t *host_id, uuid_t *claim_id)
+{
+    sqlite3_stmt *res = NULL;
+    int rc;
+
+    if (unlikely(!db_meta)) {
+        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
+            error_report("Database has not been initialized");
+        return;
+    }
+
+    rc = sqlite3_prepare_v2(db_meta, SQL_STORE_CLAIM_ID, -1, &res, 0);
+    if (unlikely(rc != SQLITE_OK)) {
+        error_report("Failed to prepare statement store chart labels");
+        return;
+    }
+
+    rc = sqlite3_bind_blob(res, 1, host_id, sizeof(*host_id), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK)) {
+        error_report("Failed to bind host_id parameter to store node instance information");
+        goto failed;
+    }
+
+    if (claim_id)
+        rc = sqlite3_bind_blob(res, 2, claim_id, sizeof(*claim_id), SQLITE_STATIC);
+    else
+        rc = sqlite3_bind_null(res, 2);
+    if (unlikely(rc != SQLITE_OK)) {
+        error_report("Failed to bind claim_id parameter to store node instance information");
+        goto failed;
+    }
+
+    rc = execute_insert(res);
+    if (unlikely(rc != SQLITE_DONE))
+        error_report("Failed to store node instance information, rc = %d", rc);
+
+failed:
+    if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
+        error_report("Failed to finalize the prepared statement when storing node instance information");
+}
+
+static void delete_dimension_uuid(uuid_t *dimension_uuid)
+{
+    static __thread sqlite3_stmt *res = NULL;
+    int rc;
+
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_meta, DELETE_DIMENSION_UUID, &res);
+        if (rc != SQLITE_OK) {
+            error_report("Failed to prepare statement to delete a dimension uuid");
+            return;
+        }
+    }
+
+    rc = sqlite3_bind_blob(res, 1, dimension_uuid,  sizeof(*dimension_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto skip_execution;
+
+    rc = sqlite3_step_monitored(res);
+    if (unlikely(rc != SQLITE_DONE))
+        error_report("Failed to delete dimension uuid, rc = %d", rc);
+
+skip_execution:
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement when deleting dimension UUID, rc = %d", rc);
+}
+
+//
+// Store host and host system info information in the database
+static int sql_store_host_info(RRDHOST *host)
+{
+    static __thread sqlite3_stmt *res = NULL;
+    int rc, param = 0;
+
+    if (unlikely(!db_meta)) {
+        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
+            return 0;
+        error_report("Database has not been initialized");
+        return 1;
+    }
+
+    if (unlikely((!res))) {
+        rc = prepare_statement(db_meta, SQL_STORE_HOST_INFO, &res);
+        if (unlikely(rc != SQLITE_OK)) {
+            error_report("Failed to prepare statement to store host, rc = %d", rc);
+            return 1;
+        }
+    }
+
+    rc = sqlite3_bind_blob(res, ++param, &host->host_uuid, sizeof(host->host_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = bind_text_null(res, ++param, rrdhost_hostname(host), 0);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = bind_text_null(res, ++param, rrdhost_registry_hostname(host), 1);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int(res, ++param, host->rrd_update_every);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = bind_text_null(res, ++param, rrdhost_os(host), 1);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = bind_text_null(res, ++param, rrdhost_timezone(host), 1);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = bind_text_null(res, ++param, rrdhost_tags(host), 1);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int(res, ++param, host->system_info ? host->system_info->hops : 0);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int(res, ++param, host->rrd_memory_mode);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = bind_text_null(res, ++param, rrdhost_abbrev_timezone(host), 1);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int(res, ++param, host->utc_offset);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = bind_text_null(res, ++param, rrdhost_program_name(host), 1);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = bind_text_null(res, ++param, rrdhost_program_version(host), 1);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int64(res, ++param, host->rrd_history_entries);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int(res, ++param, (int ) host->health_enabled);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    int store_rc = sqlite3_step_monitored(res);
+    if (unlikely(store_rc != SQLITE_DONE))
+        error_report("Failed to store host %s, rc = %d", rrdhost_hostname(host), rc);
+
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement to store host %s, rc = %d", rrdhost_hostname(host), rc);
+
+    return !(store_rc == SQLITE_DONE);
+bind_fail:
+    error_report("Failed to bind %d parameter to store host %s, rc = %d", param, rrdhost_hostname(host), rc);
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement to store host %s, rc = %d", rrdhost_hostname(host), rc);
+    return 1;
+}
+
+static void sql_store_host_system_info_key_value(const char *name, const char *value, void *data)
+{
+    struct query_build *lb = data;
+
+    if (unlikely(!value))
+        return;
+
+    if (unlikely(!lb->count))
+        buffer_sprintf(
+            lb->sql, STORE_HOST_INFO);
+    else
+        buffer_strcat(lb->sql, ", ");
+    buffer_sprintf(lb->sql, STORE_HOST_INFO_VALUES, lb->uuid_str, name, value);
+    lb->count++;
+}
+
+static BUFFER *sql_store_host_system_info(RRDHOST *host)
+{
+    struct rrdhost_system_info *system_info = host->system_info;
+
+    if (unlikely(!system_info))
+        return NULL;
+
+    BUFFER *work_buffer = buffer_create(1024);
+
+    struct query_build key_data = {.sql = work_buffer, .count = 0};
+    uuid_unparse_lower(host->host_uuid, key_data.uuid_str);
+
+    sql_store_host_system_info_key_value("NETDATA_CONTAINER_OS_NAME", system_info->container_os_name, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_CONTAINER_OS_ID", system_info->container_os_id, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_CONTAINER_OS_ID_LIKE", system_info->container_os_id_like, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_CONTAINER_OS_VERSION", system_info->container_os_version, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_CONTAINER_OS_VERSION_ID", system_info->container_os_version_id, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_CONTAINER_OS_DETECTION", system_info->host_os_detection, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_HOST_OS_NAME", system_info->host_os_name, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_HOST_OS_ID", system_info->host_os_id, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_HOST_OS_ID_LIKE", system_info->host_os_id_like, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_HOST_OS_VERSION", system_info->host_os_version, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_HOST_OS_VERSION_ID", system_info->host_os_version_id, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_HOST_OS_DETECTION", system_info->host_os_detection, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_KERNEL_NAME", system_info->kernel_name, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_CPU_LOGICAL_CPU_COUNT", system_info->host_cores, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_CPU_FREQ", system_info->host_cpu_freq, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_TOTAL_RAM", system_info->host_ram_total, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_TOTAL_DISK_SIZE", system_info->host_disk_space, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_KERNEL_VERSION", system_info->kernel_version, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_ARCHITECTURE", system_info->architecture, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_VIRTUALIZATION", system_info->virtualization, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_VIRT_DETECTION", system_info->virt_detection, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_CONTAINER", system_info->container, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_SYSTEM_CONTAINER_DETECTION", system_info->container_detection, &key_data);
+    sql_store_host_system_info_key_value("NETDATA_HOST_IS_K8S_NODE", system_info->is_k8s_node, &key_data);
+
+    return work_buffer;
+}
+
+
+/*
+ * Store set option for a dimension
+ */
+static int sql_set_dimension_option(uuid_t *dim_uuid, char *option)
+{
+    sqlite3_stmt *res = NULL;
+    int rc;
+
+    if (unlikely(!db_meta)) {
+        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
+            return 0;
+        error_report("Database has not been initialized");
+        return 1;
+    }
+
+    rc = sqlite3_prepare_v2(db_meta, "UPDATE dimension SET options = @options WHERE dim_id = @dim_id", -1, &res, 0);
+    if (unlikely(rc != SQLITE_OK)) {
+        error_report("Failed to prepare statement to update dimension options");
+        return 0;
+    };
+
+    rc = sqlite3_bind_blob(res, 2, dim_uuid, sizeof(*dim_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    if (!option || !strcmp(option,"unhide"))
+        rc = sqlite3_bind_null(res, 1);
+    else
+        rc = sqlite3_bind_text(res, 1, option, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = execute_insert(res);
+    if (unlikely(rc != SQLITE_DONE))
+        error_report("Failed to update dimension option, rc = %d", rc);
+
+bind_fail:
+    rc = sqlite3_finalize(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to finalize statement in update dimension options, rc = %d", rc);
+    return 0;
+}
+
+/*
+ * Store a chart in the database
+ */
+
+static int sql_store_chart(
+    uuid_t *chart_uuid, uuid_t *host_uuid, const char *type, const char *id, const char *name, const char *family,
+    const char *context, const char *title, const char *units, const char *plugin, const char *module, long priority,
+    int update_every, int chart_type, int memory_mode, long history_entries)
+{
+    static __thread sqlite3_stmt *res = NULL;
+    int rc, param = 0;
+
+    if (unlikely(!db_meta)) {
+        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
+            return 0;
+        error_report("Database has not been initialized");
+        return 1;
+    }
+
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_meta, SQL_STORE_CHART, &res);
+        if (unlikely(rc != SQLITE_OK)) {
+            error_report("Failed to prepare statement to store chart, rc = %d", rc);
+            return 1;
+        }
+    }
+
+    param++;
+    rc = sqlite3_bind_blob(res, 1, chart_uuid, sizeof(*chart_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_blob(res, 2, host_uuid, sizeof(*host_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_text(res, 3, type, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_text(res, 4, id, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    if (name && *name)
+        rc = sqlite3_bind_text(res, 5, name, -1, SQLITE_STATIC);
+    else
+        rc = sqlite3_bind_null(res, 5);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_text(res, 6, family, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_text(res, 7, context, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_text(res, 8, title, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_text(res, 9, units, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_text(res, 10, plugin, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_text(res, 11, module, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_int(res, 12, (int) priority);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_int(res, 13, update_every);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_int(res, 14, chart_type);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_int(res, 15, memory_mode);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    param++;
+    rc = sqlite3_bind_int(res, 16, (int) history_entries);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = execute_insert(res);
+    if (unlikely(rc != SQLITE_DONE))
+        error_report("Failed to store chart, rc = %d", rc);
+
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement in chart store function, rc = %d", rc);
+
+    return 0;
+
+bind_fail:
+    error_report("Failed to bind parameter %d to store chart, rc = %d", param, rc);
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement in chart store function, rc = %d", rc);
+    return 1;
+}
+
+/*
+ * Store a dimension
+ */
+static int sql_store_dimension(
+    uuid_t *dim_uuid, uuid_t *chart_uuid, const char *id, const char *name, collected_number multiplier,
+    collected_number divisor, int algorithm, bool hidden)
+{
+    static __thread sqlite3_stmt *res = NULL;
+    int rc, param = 0;
+
+    if (unlikely(!db_meta)) {
+        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
+            return 0;
+        error_report("Database has not been initialized");
+        return 1;
+    }
+
+    if (unlikely(!res)) {
+        rc = prepare_statement(db_meta, SQL_STORE_DIMENSION, &res);
+        if (unlikely(rc != SQLITE_OK)) {
+            error_report("Failed to prepare statement to store dimension, rc = %d", rc);
+            return 1;
+        }
+    }
+
+    rc = sqlite3_bind_blob(res, ++param, dim_uuid, sizeof(*dim_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_blob(res, ++param, chart_uuid, sizeof(*chart_uuid), SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_text(res, ++param, id, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_text(res, ++param, name, -1, SQLITE_STATIC);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int(res, ++param, (int) multiplier);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int(res, ++param, (int ) divisor);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = sqlite3_bind_int(res, ++param, algorithm);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    if (hidden)
+        rc = sqlite3_bind_text(res, ++param, "hidden", -1, SQLITE_STATIC);
+    else
+        rc = sqlite3_bind_null(res, ++param);
+    if (unlikely(rc != SQLITE_OK))
+        goto bind_fail;
+
+    rc = execute_insert(res);
+    if (unlikely(rc != SQLITE_DONE))
+        error_report("Failed to store dimension, rc = %d", rc);
+
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement in store dimension, rc = %d", rc);
+    return 0;
+
+bind_fail:
+    error_report("Failed to bind parameter %d to store dimension, rc = %d", param, rc);
+    rc = sqlite3_reset(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to reset statement in store dimension, rc = %d", rc);
+    return 1;
+}
+
+static bool dimension_can_be_deleted(uuid_t *dim_uuid)
+{
+#ifdef ENABLE_DBENGINE
+    bool no_retention = true;
+    for (size_t tier = 0; tier < storage_tiers; tier++) {
+        if (!multidb_ctx[tier])
+            continue;
+        time_t first_time_t = 0, last_time_t = 0;
+        if (rrdeng_metric_retention_by_uuid((void *) multidb_ctx[tier], dim_uuid, &first_time_t, &last_time_t) == 0) {
+            if (first_time_t > 0) {
+                no_retention = false;
+                break;
+            }
+        }
+    }
+    return no_retention;
+#else
+    return false;
+#endif
+}
+
+static void check_dimension_metadata(struct metadata_wc *wc)
+{
+    int rc;
+    sqlite3_stmt *res = NULL;
+
+    rc = sqlite3_prepare_v2(db_meta, SELECT_DIMENSION_LIST, -1, &res, 0);
+    if (unlikely(rc != SQLITE_OK)) {
+        error_report("Failed to prepare statement to fetch host dimensions");
+        return;
+    }
+
+    rc = sqlite3_bind_int64(res, 1,  (sqlite3_int64) wc->row_id);
+    if (unlikely(rc != SQLITE_OK)) {
+        error_report("Failed to row parameter");
+        goto skip_run;
+    }
+
+    uint32_t total_checked = 0;
+    uint32_t total_deleted= 0;
+    uint64_t last_row_id = wc->row_id;
+
+    info("METADATA: Checking dimensions starting after row %"PRIu64, wc->row_id);
+
+    while (sqlite3_step_monitored(res) == SQLITE_ROW && total_deleted < MAX_METADATA_CLEANUP) {
+        if (unlikely(metadata_flag_check(wc, METADATA_FLAG_SHUTDOWN)))
+            break;
+
+        last_row_id = sqlite3_column_int64(res, 1);
+        rc = dimension_can_be_deleted((uuid_t *)sqlite3_column_blob(res, 0));
+        if (rc == true) {
+            delete_dimension_uuid((uuid_t *)sqlite3_column_blob(res, 0));
+            total_deleted++;
+        }
+        total_checked++;
+    }
+    wc->row_id = last_row_id;
+    time_t now = now_realtime_sec();
+    if (total_deleted > 0) {
+        wc->check_metadata_after = now + METADATA_MAINTENANCE_RETRY;
+    } else
+        wc->row_id = 0;
+    info("METADATA: Checked %u, deleted %u -- will resume after row %"PRIu64" in %lld seconds", total_checked, total_deleted, wc->row_id,
+         (long long)(wc->check_metadata_after - now));
+
+skip_run:
+    rc = sqlite3_finalize(res);
+    if (unlikely(rc != SQLITE_OK))
+        error_report("Failed to finalize the prepared statement when reading dimensions");
+}
+
+
+//
+// EVENT LOOP STARTS HERE
+//
+static uv_mutex_t metadata_async_lock;
+
+static void metadata_init_cmd_queue(struct metadata_wc *wc)
+{
+    wc->cmd_queue.head = wc->cmd_queue.tail = 0;
+    wc->queue_size = 0;
+    fatal_assert(0 == uv_cond_init(&wc->cmd_cond));
+    fatal_assert(0 == uv_mutex_init(&wc->cmd_mutex));
+}
+
+int metadata_enq_cmd_noblock(struct metadata_wc *wc, struct metadata_cmd *cmd)
+{
+    unsigned queue_size;
+
+    /* wait for free space in queue */
+    uv_mutex_lock(&wc->cmd_mutex);
+
+    if (cmd->opcode == METADATA_SYNC_SHUTDOWN) {
+        metadata_flag_set(wc, METADATA_FLAG_SHUTDOWN);
+        uv_mutex_unlock(&wc->cmd_mutex);
+        return 0;
+    }
+
+    if (unlikely((queue_size = wc->queue_size) == METADATA_CMD_Q_MAX_SIZE ||
+        metadata_flag_check(wc, METADATA_FLAG_SHUTDOWN))) {
+        uv_mutex_unlock(&wc->cmd_mutex);
+        return 1;
+    }
+
+    fatal_assert(queue_size < METADATA_CMD_Q_MAX_SIZE);
+    /* enqueue command */
+    wc->cmd_queue.cmd_array[wc->cmd_queue.tail] = *cmd;
+    wc->cmd_queue.tail = wc->cmd_queue.tail != METADATA_CMD_Q_MAX_SIZE - 1 ?
+                             wc->cmd_queue.tail + 1 : 0;
+    wc->queue_size = queue_size + 1;
+    uv_mutex_unlock(&wc->cmd_mutex);
+    return 0;
+}
+
+static void metadata_enq_cmd(struct metadata_wc *wc, struct metadata_cmd *cmd)
+{
+    unsigned queue_size;
+
+    /* wait for free space in queue */
+    uv_mutex_lock(&wc->cmd_mutex);
+    if (unlikely(metadata_flag_check(wc, METADATA_FLAG_SHUTDOWN))) {
+        uv_mutex_unlock(&wc->cmd_mutex);
+        (void) uv_async_send(&wc->async);
+        return;
+    }
+
+    if (cmd->opcode == METADATA_SYNC_SHUTDOWN) {
+        metadata_flag_set(wc, METADATA_FLAG_SHUTDOWN);
+        uv_mutex_unlock(&wc->cmd_mutex);
+        (void) uv_async_send(&wc->async);
+        return;
+    }
+
+    while ((queue_size = wc->queue_size) == METADATA_CMD_Q_MAX_SIZE) {
+        if (unlikely(metadata_flag_check(wc, METADATA_FLAG_SHUTDOWN))) {
+            uv_mutex_unlock(&wc->cmd_mutex);
+            return;
+        }
+        uv_cond_wait(&wc->cmd_cond, &wc->cmd_mutex);
+    }
+    fatal_assert(queue_size < METADATA_CMD_Q_MAX_SIZE);
+    /* enqueue command */
+    wc->cmd_queue.cmd_array[wc->cmd_queue.tail] = *cmd;
+    wc->cmd_queue.tail = wc->cmd_queue.tail != METADATA_CMD_Q_MAX_SIZE - 1 ?
+                             wc->cmd_queue.tail + 1 : 0;
+    wc->queue_size = queue_size + 1;
+    uv_mutex_unlock(&wc->cmd_mutex);
+
+    /* wake up event loop */
+    (void) uv_async_send(&wc->async);
+}
+
+static struct metadata_cmd metadata_deq_cmd(struct metadata_wc *wc, enum metadata_opcode *next_opcode)
+{
+    struct metadata_cmd ret;
+    unsigned queue_size;
+
+    uv_mutex_lock(&wc->cmd_mutex);
+    queue_size = wc->queue_size;
+    if (queue_size == 0) {
+        memset(&ret, 0, sizeof(ret));
+        ret.opcode = METADATA_DATABASE_NOOP;
+        ret.completion = NULL;
+        *next_opcode = METADATA_DATABASE_NOOP;
+    } else {
+        /* dequeue command */
+        ret = wc->cmd_queue.cmd_array[wc->cmd_queue.head];
+
+        if (queue_size == 1) {
+            wc->cmd_queue.head = wc->cmd_queue.tail = 0;
+        } else {
+            wc->cmd_queue.head = wc->cmd_queue.head != METADATA_CMD_Q_MAX_SIZE - 1 ?
+                                     wc->cmd_queue.head + 1 : 0;
+        }
+        wc->queue_size = queue_size - 1;
+        if (wc->queue_size > 0)
+            *next_opcode = wc->cmd_queue.cmd_array[wc->cmd_queue.head].opcode;
+        else
+            *next_opcode = METADATA_DATABASE_NOOP;
+        /* wake up producers */
+        uv_cond_signal(&wc->cmd_cond);
+    }
+    uv_mutex_unlock(&wc->cmd_mutex);
+
+    return ret;
+}
+
+static void async_cb(uv_async_t *handle)
+{
+    uv_stop(handle->loop);
+    uv_update_time(handle->loop);
+}
+
+#define TIMER_INITIAL_PERIOD_MS (1000)
+#define TIMER_REPEAT_PERIOD_MS (1000)
+
+static void timer_cb(uv_timer_t* handle)
+{
+    uv_stop(handle->loop);
+    uv_update_time(handle->loop);
+
+   struct metadata_wc *wc = handle->data;
+   struct metadata_cmd cmd;
+   memset(&cmd, 0, sizeof(cmd));
+
+   time_t now = now_realtime_sec();
+
+   if (wc->check_metadata_after && wc->check_metadata_after < now) {
+       cmd.opcode = METADATA_MAINTENANCE;
+       if (!metadata_enq_cmd_noblock(wc, &cmd))
+           wc->check_metadata_after = now + METADATA_MAINTENANCE_INTERVAL;
+   }
+
+   if (wc->check_hosts_after && wc->check_hosts_after < now) {
+       cmd.opcode = METADATA_SCAN_HOSTS;
+       if (!metadata_enq_cmd_noblock(wc, &cmd))
+           wc->check_hosts_after = now + METADATA_HOST_CHECK_INTERVAL;
+   }
+}
+
+static void after_metadata_cleanup(uv_work_t *req, int status)
+{
+    UNUSED(status);
+
+    struct metadata_wc *wc = req->data;
+    metadata_flag_clear(wc, METADATA_FLAG_CLEANUP);
+}
+static void start_metadata_cleanup(uv_work_t *req)
+{
+    struct metadata_wc *wc = req->data;
+    check_dimension_metadata(wc);
+}
+
+struct scan_metadata_payload {
+    uv_work_t request;
+    struct metadata_wc *wc;
+    struct completion *completion;
+    uint32_t max_count;
+};
+
+// Callback after scan of hosts is done
+static void after_metadata_hosts(uv_work_t *req, int status __maybe_unused)
+{
+    struct scan_metadata_payload *data = req->data;
+    struct metadata_wc *wc = data->wc;
+
+    metadata_flag_clear(wc, METADATA_FLAG_SCANNING_HOSTS);
+    internal_error(true, "METADATA: scanning hosts complete");
+    if (unlikely(data->completion)) {
+        completion_mark_complete(data->completion);
+        internal_error(true, "METADATA: Sending completion done");
+    }
+    freez(data);
+}
+
+static bool metadata_scan_host(RRDHOST *host, uint32_t max_count) {
+    RRDSET *st;
+    int rc;
+
+    bool more_to_do = false;
+    uint32_t scan_count = 1;
+    BUFFER *work_buffer = buffer_create(1024);
+
+    rrdset_foreach_reentrant(st, host) {
+        if (scan_count == max_count) {
+            more_to_do = true;
+            break;
+        }
+        if(rrdset_flag_check(st, RRDSET_FLAG_METADATA_UPDATE)) {
+            rrdset_flag_clear(st, RRDSET_FLAG_METADATA_UPDATE);
+            scan_count++;
+
+            check_and_update_chart_labels(st, work_buffer);
+
+            rc = sql_store_chart(
+                &st->chart_uuid,
+                &st->rrdhost->host_uuid,
+                string2str(st->parts.type),
+                string2str(st->parts.id),
+                string2str(st->parts.name),
+                rrdset_family(st),
+                rrdset_context(st),
+                rrdset_title(st),
+                rrdset_units(st),
+                rrdset_plugin_name(st),
+                rrdset_module_name(st),
+                st->priority,
+                st->update_every,
+                st->chart_type,
+                st->rrd_memory_mode,
+                st->entries);
+            if (unlikely(rc))
+                internal_error(true, "METADATA: Failed to store chart metadata %s", string2str(st->id));
+        }
+
+        RRDDIM *rd;
+        rrddim_foreach_read(rd, st) {
+            if(rrddim_flag_check(rd, RRDDIM_FLAG_METADATA_UPDATE)) {
+                rrddim_flag_clear(rd, RRDDIM_FLAG_METADATA_UPDATE);
+
+                rc = sql_store_dimension(
+                    &rd->metric_uuid,
+                    &rd->rrdset->chart_uuid,
+                    string2str(rd->id),
+                    string2str(rd->name),
+                    rd->multiplier,
+                    rd->divisor,
+                    rd->algorithm,
+                    rrddim_option_check(rd, RRDDIM_OPTION_HIDDEN));
+
+                if (unlikely(rc))
+                    error_report("METADATA: Failed to store dimension %s", string2str(rd->id));
+            }
+        }
+        rrddim_foreach_done(rd);
+    }
+    rrdset_foreach_done(st);
+
+    buffer_free(work_buffer);
+    return more_to_do;
+}
+
+// Worker thread to scan hosts for pending metadata to store
+static void start_metadata_hosts(uv_work_t *req __maybe_unused)
+{
+    RRDHOST *host;
+
+    struct scan_metadata_payload *data = req->data;
+    struct metadata_wc *wc = data->wc;
+
+    bool run_again = false;
+    dfe_start_reentrant(rrdhost_root_index, host) {
+        if (rrdhost_flag_check(host, RRDHOST_FLAG_ARCHIVED) || !rrdhost_flag_check(host, RRDHOST_FLAG_METADATA_UPDATE))
+            continue;
+        internal_error(true, "METADATA: Scanning host %s", rrdhost_hostname(host));
+        rrdhost_flag_clear(host,RRDHOST_FLAG_METADATA_UPDATE);
+        if (unlikely(metadata_scan_host(host, data->max_count))) {
+            run_again = true;
+            rrdhost_flag_set(host,RRDHOST_FLAG_METADATA_UPDATE);
+            internal_error(true,"METADATA: Rescheduling host %s to run; more charts to store", rrdhost_hostname(host));
+        }
+    }
+    dfe_done(host);
+    if (unlikely(run_again))
+        wc->check_hosts_after = now_realtime_sec() + METADATA_HOST_CHECK_IMMEDIATE;
+    else
+        wc->check_hosts_after = now_realtime_sec() + METADATA_HOST_CHECK_INTERVAL;
+}
+
+static void metadata_event_loop(void *arg)
+{
+    worker_register("METASYNC");
+    worker_register_job_name(METADATA_DATABASE_NOOP,        "noop");
+    worker_register_job_name(METADATA_DATABASE_TIMER,       "timer");
+    worker_register_job_name(METADATA_ADD_CHART,            "add chart");
+    worker_register_job_name(METADATA_ADD_CHART_LABEL,      "add chart label");
+    worker_register_job_name(METADATA_ADD_DIMENSION,        "add dimension");
+    worker_register_job_name(METADATA_DEL_DIMENSION,        "delete dimension");
+    worker_register_job_name(METADATA_ADD_DIMENSION_OPTION, "dimension option");
+    worker_register_job_name(METADATA_ADD_HOST_SYSTEM_INFO, "host system info");
+    worker_register_job_name(METADATA_ADD_HOST_INFO,        "host info");
+    worker_register_job_name(METADATA_STORE_CLAIM_ID,       "add claim id");
+    worker_register_job_name(METADATA_STORE_HOST_LABELS,    "host labels");
+    worker_register_job_name(METADATA_MAINTENANCE,          "maintenance");
+
+
+    int ret;
+    uv_loop_t *loop;
+    unsigned cmd_batch_size;
+    struct metadata_wc *wc = arg;
+    enum metadata_opcode opcode, next_opcode;
+    uv_work_t metadata_cleanup_worker;
+
+    uv_thread_set_name_np(wc->thread, "METASYNC");
+    loop = wc->loop = mallocz(sizeof(uv_loop_t));
+    ret = uv_loop_init(loop);
+    if (ret) {
+        error("uv_loop_init(): %s", uv_strerror(ret));
+        goto error_after_loop_init;
+    }
+    loop->data = wc;
+
+    ret = uv_async_init(wc->loop, &wc->async, async_cb);
+    if (ret) {
+        error("uv_async_init(): %s", uv_strerror(ret));
+        goto error_after_async_init;
+    }
+    wc->async.data = wc;
+
+    ret = uv_timer_init(loop, &wc->timer_req);
+    if (ret) {
+        error("uv_timer_init(): %s", uv_strerror(ret));
+        goto error_after_timer_init;
+    }
+    wc->timer_req.data = wc;
+    fatal_assert(0 == uv_timer_start(&wc->timer_req, timer_cb, TIMER_INITIAL_PERIOD_MS, TIMER_REPEAT_PERIOD_MS));
+
+    info("Starting metadata sync thread with %d entries command queue", METADATA_CMD_Q_MAX_SIZE);
+
+    struct metadata_cmd cmd;
+    memset(&cmd, 0, sizeof(cmd));
+    metadata_flag_clear(wc, METADATA_FLAG_CLEANUP);
+    metadata_flag_clear(wc, METADATA_FLAG_SCANNING_HOSTS);
+
+    wc->check_metadata_after = now_realtime_sec() + METADATA_MAINTENANCE_FIRST_CHECK;
+    wc->check_hosts_after    = now_realtime_sec() + METADATA_HOST_CHECK_FIRST_CHECK;
+
+    int shutdown = 0;
+    int in_transaction = 0;
+    int commands_in_transaction = 0;
+    // This can be used in the event loop for all opcodes (not workers)
+    BUFFER *work_buffer = buffer_create(1024);
+    wc->row_id = 0;
+    completion_mark_complete(&wc->init_complete);
+
+    while (shutdown == 0 || (wc->flags & METADATA_WORKER_BUSY)) {
+        RRDDIM *rd = NULL;
+        RRDSET *st = NULL;
+        RRDHOST *host = NULL;
+        DICTIONARY_ITEM *dict_item = NULL;
+        BUFFER *buffer = NULL;
+        uuid_t  *uuid;
+        int rc;
+
+        worker_is_idle();
+        uv_run(loop, UV_RUN_DEFAULT);
+
+        /* wait for commands */
+        cmd_batch_size = 0;
+        do {
+            if (unlikely(cmd_batch_size >= METADATA_MAX_BATCH_SIZE))
+                break;
+
+            cmd = metadata_deq_cmd(wc, &next_opcode);
+            opcode = cmd.opcode;
+
+            if (unlikely(opcode == METADATA_DATABASE_NOOP && metadata_flag_check(wc, METADATA_FLAG_SHUTDOWN))) {
+                shutdown = 1;
+                continue;
+            }
+
+            ++cmd_batch_size;
+
+            // If we are not in transaction and this command is the same with the next ; start a transaction
+            if (!in_transaction && opcode < METADATA_SKIP_TRANSACTION && opcode == next_opcode) {
+                if (opcode != METADATA_DATABASE_NOOP) {
+                    in_transaction = 1;
+                    db_execute("BEGIN TRANSACTION;");
+                }
+            }
+
+            if (likely(in_transaction)) {
+                commands_in_transaction++;
+            }
+
+            if (likely(opcode != METADATA_DATABASE_NOOP))
+                    worker_is_busy(opcode);
+
+            switch (opcode) {
+                case METADATA_DATABASE_NOOP:
+                case METADATA_DATABASE_TIMER:
+                    break;
+                case METADATA_ADD_CHART:
+                    dict_item = (DICTIONARY_ITEM * ) cmd.param[0];
+                    st = (RRDSET *) dictionary_acquired_item_value(dict_item);
+
+                    rc = sql_store_chart(
+                        &st->chart_uuid,
+                        &st->rrdhost->host_uuid,
+                        string2str(st->parts.type),
+                        string2str(st->parts.id),
+                        string2str(st->parts.name),
+                        rrdset_family(st),
+                        rrdset_context(st),
+                        rrdset_title(st),
+                        rrdset_units(st),
+                        rrdset_plugin_name(st),
+                        rrdset_module_name(st),
+                        st->priority,
+                        st->update_every,
+                        st->chart_type,
+                        st->rrd_memory_mode,
+                        st->entries);
+
+                    if (unlikely(rc))
+                        error_report("Failed to store chart %s", rrdset_id(st));
+
+                    dictionary_acquired_item_release(st->rrdhost->rrdset_root_index, dict_item);
+                    break;
+                case METADATA_ADD_CHART_LABEL:
+                    dict_item = (DICTIONARY_ITEM * ) cmd.param[0];
+                    st = (RRDSET *) dictionary_acquired_item_value(dict_item);
+                    check_and_update_chart_labels(st, work_buffer);
+                    dictionary_acquired_item_release(st->rrdhost->rrdset_root_index, dict_item);
+                    break;
+                case METADATA_ADD_DIMENSION:
+                    dict_item = (DICTIONARY_ITEM * ) cmd.param[0];
+                    rd = (RRDDIM *) dictionary_acquired_item_value(dict_item);
+
+                    rc = sql_store_dimension(
+                        &rd->metric_uuid,
+                        &rd->rrdset->chart_uuid,
+                        string2str(rd->id),
+                        string2str(rd->name),
+                        rd->multiplier,
+                        rd->divisor,
+                        rd->algorithm,
+                        rrddim_option_check(rd, RRDDIM_OPTION_HIDDEN));
+
+                    if (unlikely(rc))
+                        error_report("Failed to store dimension %s", rrddim_id(rd));
+
+                    dictionary_acquired_item_release(rd->rrdset->rrddim_root_index, dict_item);
+                    break;
+                case METADATA_DEL_DIMENSION:
+                    uuid = (uuid_t *) cmd.param[0];
+                    if (likely(dimension_can_be_deleted(uuid)))
+                        delete_dimension_uuid(uuid);
+                    freez(uuid);
+                    break;
+                case METADATA_ADD_DIMENSION_OPTION:
+                    dict_item = (DICTIONARY_ITEM * ) cmd.param[0];
+                    rd = (RRDDIM *) dictionary_acquired_item_value(dict_item);
+                    rc = sql_set_dimension_option(
+                        &rd->metric_uuid, rrddim_flag_check(rd, RRDDIM_FLAG_META_HIDDEN) ? "hidden" : NULL);
+                    if (unlikely(rc))
+                        error_report("Failed to store dimension option for %s", string2str(rd->id));
+                    dictionary_acquired_item_release(rd->rrdset->rrddim_root_index, dict_item);
+                    break;
+                case METADATA_ADD_HOST_SYSTEM_INFO:
+                    buffer = (BUFFER *) cmd.param[0];
+                    db_execute(buffer_tostring(buffer));
+                    buffer_free(buffer);
+                    break;
+                case METADATA_ADD_HOST_INFO:
+                    dict_item = (DICTIONARY_ITEM * ) cmd.param[0];
+                    host = (RRDHOST *) dictionary_acquired_item_value(dict_item);
+                    rc = sql_store_host_info(host);
+                    if (unlikely(rc))
+                        error_report("Failed to store host info in the database for %s", string2str(host->hostname));
+                    dictionary_acquired_item_release(rrdhost_root_index, dict_item);
+                    break;
+                case METADATA_STORE_CLAIM_ID:
+                    store_claim_id((uuid_t *) cmd.param[0], (uuid_t *) cmd.param[1]);
+                    freez((void *) cmd.param[0]);
+                    freez((void *) cmd.param[1]);
+                    break;
+                case METADATA_STORE_HOST_LABELS:
+                    dict_item = (DICTIONARY_ITEM * ) cmd.param[0];
+                    host = (RRDHOST *) dictionary_acquired_item_value(dict_item);
+                    rc = exec_statement_with_uuid(SQL_DELETE_HOST_LABELS, &host->host_uuid);
+
+                    if (likely(rc == SQLITE_OK)) {
+                        buffer_flush(work_buffer);
+                        struct query_build tmp = {.sql = work_buffer, .count = 0};
+                        uuid_unparse_lower(host->host_uuid, tmp.uuid_str);
+                        rrdlabels_walkthrough_read(host->rrdlabels, host_label_store_to_sql_callback, &tmp);
+                        db_execute(buffer_tostring(work_buffer));
+                    }
+
+                    dictionary_acquired_item_release(rrdhost_root_index, dict_item);
+                    break;
+
+                case METADATA_SCAN_HOSTS:
+                    if (unlikely(metadata_flag_check(wc, METADATA_FLAG_SCANNING_HOSTS)))
+                        break;
+
+                    struct scan_metadata_payload *data = mallocz(sizeof(*data));
+                    data->request.data = data;
+                    data->wc = wc;
+                    data->completion = cmd.completion;  // Completion by the worker
+
+                    if (unlikely(cmd.completion)) {
+                        data->max_count = 0;            // 0 will process all pending updates
+                        cmd.completion = NULL;          // Do not complete after launching worker (worker will do)
+                    }
+                    else
+                        data->max_count = 1000;
+
+                    metadata_flag_set(wc, METADATA_FLAG_SCANNING_HOSTS);
+                    if (unlikely(
+                            uv_queue_work(loop,&data->request,
+                                          start_metadata_hosts,
+                                          after_metadata_hosts))) {
+                        // Failed to launch worker -- let the event loop handle completion
+                        cmd.completion = data->completion;
+                        freez(data);
+                        metadata_flag_clear(wc, METADATA_FLAG_SCANNING_HOSTS);
+                    }
+                    break;
+                case METADATA_STORE_BUFFER:
+                    buffer = (BUFFER *) cmd.param[0];
+                    db_execute(buffer_tostring(buffer));
+                    buffer_free(buffer);
+                    break;
+                case METADATA_MAINTENANCE:
+                    if (unlikely(metadata_flag_check(wc, METADATA_FLAG_CLEANUP)))
+                        break;
+
+                    metadata_cleanup_worker.data = wc;
+                    metadata_flag_set(wc, METADATA_FLAG_CLEANUP);
+                    if (unlikely(
+                            uv_queue_work(loop, &metadata_cleanup_worker, start_metadata_cleanup, after_metadata_cleanup))) {
+                        metadata_flag_clear(wc, METADATA_FLAG_CLEANUP);
+                    }
+                    break;
+                case METADATA_UNITTEST:;
+                    struct thread_unittest *tu = (struct thread_unittest *) cmd.param[0];
+                    sleep_usec(1000); // processing takes 1ms
+                    __atomic_fetch_add(&tu->processed, 1, __ATOMIC_SEQ_CST);
+                    break;
+                default:
+                    break;
+            }
+            if (in_transaction && (commands_in_transaction >= METADATA_MAX_TRANSACTION_BATCH || opcode != next_opcode)) {
+                in_transaction = 0;
+                db_execute("COMMIT TRANSACTION;");
+                commands_in_transaction = 0;
+            }
+
+            if (cmd.completion)
+                completion_mark_complete(cmd.completion);
+        } while (opcode != METADATA_DATABASE_NOOP);
+    }
+
+    if (!uv_timer_stop(&wc->timer_req))
+        uv_close((uv_handle_t *)&wc->timer_req, NULL);
+
+    /*
+     * uv_async_send after uv_close does not seem to crash in linux at the moment,
+     * it is however undocumented behaviour we need to be aware if this becomes
+     * an issue in the future.
+     */
+    uv_close((uv_handle_t *)&wc->async, NULL);
+    uv_run(loop, UV_RUN_DEFAULT);
+
+    uv_cond_destroy(&wc->cmd_cond);
+    /*  uv_mutex_destroy(&wc->cmd_mutex); */
+    //fatal_assert(0 == uv_loop_close(loop));
+    int rc;
+
+    do {
+        rc = uv_loop_close(loop);
+    } while (rc != UV_EBUSY);
+
+    freez(loop);
+    worker_unregister();
+
+    buffer_free(work_buffer);
+    info("METADATA: Shutting down event loop");
+    completion_mark_complete(&wc->init_complete);
+    return;
+
+error_after_timer_init:
+    uv_close((uv_handle_t *)&wc->async, NULL);
+error_after_async_init:
+    fatal_assert(0 == uv_loop_close(loop));
+error_after_loop_init:
+    freez(loop);
+    worker_unregister();
+}
+
+struct metadata_wc metasync_worker = {.loop = NULL};
+
+void metadata_sync_shutdown(void)
+{
+    completion_init(&metasync_worker.init_complete);
+
+    struct metadata_cmd cmd;
+    memset(&cmd, 0, sizeof(cmd));
+    info("METADATA: Sending a shutdown command");
+    cmd.opcode = METADATA_SYNC_SHUTDOWN;
+    metadata_enq_cmd(&metasync_worker, &cmd);
+
+    /* wait for metadata thread to shut down */
+    info("METADATA: Waiting for shutdown ACK");
+    completion_wait_for(&metasync_worker.init_complete);
+    completion_destroy(&metasync_worker.init_complete);
+    info("METADATA: Shutdown complete");
+}
+
+void metadata_sync_shutdown_prepare(void)
+{
+    struct metadata_cmd cmd;
+    memset(&cmd, 0, sizeof(cmd));
+
+    struct completion compl;
+    completion_init(&compl);
+
+    info("METADATA: Sending a scan host command");
+    uint32_t max_wait_iterations = 2000;
+    while (unlikely(metadata_flag_check(&metasync_worker, METADATA_FLAG_SCANNING_HOSTS)) && max_wait_iterations--) {
+        if (max_wait_iterations == 1999)
+            info("METADATA: Current worker is running; waiting to finish");
+        sleep_usec(1000);
+    }
+
+    cmd.opcode = METADATA_SCAN_HOSTS;
+    cmd.completion = &compl;
+    metadata_enq_cmd(&metasync_worker, &cmd);
+
+    info("METADATA: Waiting for host scan completion");
+    completion_wait_for(&compl);
+    completion_destroy(&compl);
+    info("METADATA: Host scan complete; can continue with shutdown");
+}
+
+// -------------------------------------------------------------
+// Init function called on agent startup
+
+void metadata_sync_init(void)
+{
+    struct metadata_wc *wc = &metasync_worker;
+
+    fatal_assert(0 == uv_mutex_init(&metadata_async_lock));
+
+    memset(wc, 0, sizeof(*wc));
+    metadata_init_cmd_queue(wc);
+    completion_init(&wc->init_complete);
+
+    fatal_assert(0 == uv_thread_create(&(wc->thread), metadata_event_loop, wc));
+
+    completion_wait_for(&wc->init_complete);
+    completion_destroy(&wc->init_complete);
+
+    info("SQLite metadata sync initialization complete");
+}
+
+
+//  Helpers
+
+static inline void queue_metadata_cmd(enum metadata_opcode opcode, const void *param0, const void *param1)
+{
+    struct metadata_cmd cmd;
+    cmd.opcode = opcode;
+    cmd.param[0] = param0;
+    cmd.param[1] = param1;
+    cmd.completion = NULL;
+    metadata_enq_cmd(&metasync_worker, &cmd);
+
+}
+
+// Public
+void metaqueue_chart_update(RRDSET *st)
+{
+    const DICTIONARY_ITEM *acquired_st = dictionary_get_and_acquire_item(st->rrdhost->rrdset_root_index, string2str(st->id));
+    queue_metadata_cmd(METADATA_ADD_CHART, acquired_st, NULL);
+}
+
+//
+// RD may not be collected, so we may store it needlessly
+void metaqueue_dimension_update(RRDDIM *rd)
+{
+    const DICTIONARY_ITEM *acquired_rd =
+        dictionary_get_and_acquire_item(rd->rrdset->rrddim_root_index, string2str(rd->id));
+
+    if (unlikely(rrdset_flag_check(rd->rrdset, RRDSET_FLAG_METADATA_UPDATE))) {
+        metaqueue_chart_update(rd->rrdset);
+        rrdset_flag_clear(rd->rrdset, RRDSET_FLAG_METADATA_UPDATE);
+    }
+
+    queue_metadata_cmd(METADATA_ADD_DIMENSION, acquired_rd, NULL);
+}
+
+void metaqueue_dimension_update_flags(RRDDIM *rd)
+{
+    const DICTIONARY_ITEM *acquired_rd =
+        dictionary_get_and_acquire_item(rd->rrdset->rrddim_root_index, string2str(rd->id));
+    queue_metadata_cmd(METADATA_ADD_DIMENSION_OPTION, acquired_rd, NULL);
+}
+
+void metaqueue_host_update_system_info(RRDHOST *host)
+{
+    BUFFER *work_buffer = sql_store_host_system_info(host);
+
+    if (unlikely(!work_buffer))
+        return;
+
+    queue_metadata_cmd(METADATA_ADD_HOST_SYSTEM_INFO, work_buffer, NULL);
+}
+
+void metaqueue_host_update_info(const char *machine_guid)
+{
+    const DICTIONARY_ITEM *acquired_host = dictionary_get_and_acquire_item(rrdhost_root_index, machine_guid);
+    queue_metadata_cmd(METADATA_ADD_HOST_INFO, acquired_host, NULL);
+}
+
+void metaqueue_delete_dimension_uuid(uuid_t *uuid)
+{
+    if (unlikely(!metasync_worker.loop))
+        return;
+    uuid_t *use_uuid = mallocz(sizeof(*uuid));
+    uuid_copy(*use_uuid, *uuid);
+    queue_metadata_cmd(METADATA_DEL_DIMENSION, use_uuid, NULL);
+}
+
+void metaqueue_store_claim_id(uuid_t *host_uuid, uuid_t *claim_uuid)
+{
+    if (unlikely(!host_uuid))
+        return;
+
+    uuid_t *local_host_uuid = mallocz(sizeof(*host_uuid));
+    uuid_t *local_claim_uuid = NULL;
+
+    uuid_copy(*local_host_uuid, *host_uuid);
+    if (likely(claim_uuid)) {
+        local_claim_uuid = mallocz(sizeof(*claim_uuid));
+        uuid_copy(*local_claim_uuid, *claim_uuid);
+    }
+    queue_metadata_cmd(METADATA_STORE_CLAIM_ID, local_host_uuid, local_claim_uuid);
+}
+
+void metaqueue_store_host_labels(const char *machine_guid)
+{
+    const DICTIONARY_ITEM *acquired_host = dictionary_get_and_acquire_item(rrdhost_root_index, machine_guid);
+    queue_metadata_cmd(METADATA_STORE_HOST_LABELS, acquired_host, NULL);
+}
+
+void metaqueue_buffer(BUFFER *buffer)
+{
+    queue_metadata_cmd(METADATA_STORE_BUFFER, buffer, NULL);
+}
+
+void metaqueue_chart_labels(RRDSET *st)
+{
+    const DICTIONARY_ITEM *acquired_st = dictionary_get_and_acquire_item(st->rrdhost->rrdset_root_index, string2str(st->id));
+    queue_metadata_cmd(METADATA_ADD_CHART_LABEL, acquired_st, NULL);
+}
+
+
+//
+// unitests
+//
+
+static void *unittest_queue_metadata(void *arg) {
+    struct thread_unittest *tu = arg;
+
+    struct metadata_cmd cmd;
+    cmd.opcode = METADATA_UNITTEST;
+    cmd.param[0] = tu;
+    cmd.param[1] = NULL;
+    cmd.completion = NULL;
+    metadata_enq_cmd(&metasync_worker, &cmd);
+
+    do {
+        __atomic_fetch_add(&tu->added, 1, __ATOMIC_SEQ_CST);
+        metadata_enq_cmd(&metasync_worker, &cmd);
+        sleep_usec(10000);
+    } while (!__atomic_load_n(&tu->join, __ATOMIC_RELAXED));
+    return arg;
+}
+
+static void *metadata_unittest_threads(void)
+{
+
+    unsigned done;
+
+    struct thread_unittest tu = {
+        .join = 0,
+        .added = 0,
+        .processed = 0,
+        .done = &done,
+    };
+
+    // Queue messages / Time it
+    time_t seconds_to_run = 5;
+    int threads_to_create = 4;
+    fprintf(
+        stderr,
+        "\nChecking metadata queue using %d threads for %lld seconds...\n",
+        threads_to_create,
+        (long long)seconds_to_run);
+
+    netdata_thread_t threads[threads_to_create];
+    tu.join = 0;
+    for (int i = 0; i < threads_to_create; i++) {
+        char buf[100 + 1];
+        snprintf(buf, 100, "meta%d", i);
+        netdata_thread_create(
+            &threads[i],
+            buf,
+            NETDATA_THREAD_OPTION_DONT_LOG | NETDATA_THREAD_OPTION_JOINABLE,
+            unittest_queue_metadata,
+            &tu);
+    }
+    uv_async_send(&metasync_worker.async);
+    sleep_usec(seconds_to_run * USEC_PER_SEC);
+
+    __atomic_store_n(&tu.join, 1, __ATOMIC_RELAXED);
+    for (int i = 0; i < threads_to_create; i++) {
+        void *retval;
+        netdata_thread_join(threads[i], &retval);
+    }
+//    uv_async_send(&metasync_worker.async);
+    sleep_usec(5 * USEC_PER_SEC);
+
+    fprintf(stderr, "Added %u elements, processed %u\n", tu.added, tu.processed);
+
+    return 0;
+}
+
+int metadata_unittest(void)
+{
+    metadata_sync_init();
+
+    // Queue items for a specific period of time
+    metadata_unittest_threads();
+
+    fprintf(stderr, "Items still in queue %u\n", metasync_worker.queue_size);
+    metadata_sync_shutdown();
+
+    return 0;
+}
diff --git a/database/sqlite/sqlite_metadata.h b/database/sqlite/sqlite_metadata.h
new file mode 100644
index 000000000..9293facf8
--- /dev/null
+++ b/database/sqlite/sqlite_metadata.h
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_SQLITE_METADATA_H
+#define NETDATA_SQLITE_METADATA_H
+
+#include "sqlite3.h"
+#include "sqlite_functions.h"
+
+// To initialize and shutdown
+void metadata_sync_init(void);
+void metadata_sync_shutdown(void);
+void metadata_sync_shutdown_prepare(void);
+
+void metaqueue_dimension_update(RRDDIM *rd);
+void metaqueue_chart_update(RRDSET *st);
+void metaqueue_dimension_update_flags(RRDDIM *rd);
+void metaqueue_host_update_system_info(RRDHOST *host);
+void metaqueue_host_update_info(const char *machine_guid);
+void metaqueue_delete_dimension_uuid(uuid_t *uuid);
+void metaqueue_store_claim_id(uuid_t *host_uuid, uuid_t *claim_uuid);
+void metaqueue_store_host_labels(const char *machine_guid);
+void metaqueue_chart_labels(RRDSET *st);
+void migrate_localhost(uuid_t *host_uuid);
+void metaqueue_buffer(BUFFER *buffer);
+
+// UNIT TEST
+int metadata_unittest(void);
+#endif //NETDATA_SQLITE_METADATA_H
diff --git a/database/storage_engine.c b/database/storage_engine.c
index 76597acd5..edf017db4 100644
--- a/database/storage_engine.c
+++ b/database/storage_engine.c
@@ -10,7 +10,10 @@
     .init = rrddim_collect_init,\
     .store_metric = rrddim_collect_store_metric,\
     .flush = rrddim_store_metric_flush,\
-    .finalize = rrddim_collect_finalize\
+    .finalize = rrddim_collect_finalize, \
+    .change_collection_frequency = rrddim_store_metric_change_collection_frequency, \
+    .metrics_group_get = rrddim_metrics_group_get, \
+    .metrics_group_release = rrddim_metrics_group_release, \
 }
 
 #define im_query_ops { \
@@ -27,8 +30,10 @@ static STORAGE_ENGINE engines[] = {
         .id = RRD_MEMORY_MODE_NONE,
         .name = RRD_MEMORY_MODE_NONE_NAME,
         .api = {
-            .init = rrddim_metric_init,
-            .free = rrddim_metric_free,
+            .metric_get = rrddim_metric_get,
+            .metric_get_or_create = rrddim_metric_get_or_create,
+            .metric_dup = rrddim_metric_dup,
+            .metric_release = rrddim_metric_release,
             .collect_ops = im_collect_ops,
             .query_ops = im_query_ops
         }
@@ -37,8 +42,10 @@ static STORAGE_ENGINE engines[] = {
         .id = RRD_MEMORY_MODE_RAM,
         .name = RRD_MEMORY_MODE_RAM_NAME,
         .api = {
-            .init = rrddim_metric_init,
-            .free = rrddim_metric_free,
+            .metric_get = rrddim_metric_get,
+            .metric_get_or_create = rrddim_metric_get_or_create,
+            .metric_dup = rrddim_metric_dup,
+            .metric_release = rrddim_metric_release,
             .collect_ops = im_collect_ops,
             .query_ops = im_query_ops
         }
@@ -47,8 +54,10 @@ static STORAGE_ENGINE engines[] = {
         .id = RRD_MEMORY_MODE_MAP,
         .name = RRD_MEMORY_MODE_MAP_NAME,
         .api = {
-            .init = rrddim_metric_init,
-            .free = rrddim_metric_free,
+            .metric_get = rrddim_metric_get,
+            .metric_get_or_create = rrddim_metric_get_or_create,
+            .metric_dup = rrddim_metric_dup,
+            .metric_release = rrddim_metric_release,
             .collect_ops = im_collect_ops,
             .query_ops = im_query_ops
         }
@@ -57,8 +66,10 @@ static STORAGE_ENGINE engines[] = {
         .id = RRD_MEMORY_MODE_SAVE,
         .name = RRD_MEMORY_MODE_SAVE_NAME,
         .api = {
-            .init = rrddim_metric_init,
-            .free = rrddim_metric_free,
+            .metric_get = rrddim_metric_get,
+            .metric_get_or_create = rrddim_metric_get_or_create,
+            .metric_dup = rrddim_metric_dup,
+            .metric_release = rrddim_metric_release,
             .collect_ops = im_collect_ops,
             .query_ops = im_query_ops
         }
@@ -67,8 +78,10 @@ static STORAGE_ENGINE engines[] = {
         .id = RRD_MEMORY_MODE_ALLOC,
         .name = RRD_MEMORY_MODE_ALLOC_NAME,
         .api = {
-            .init = rrddim_metric_init,
-            .free = rrddim_metric_free,
+            .metric_get = rrddim_metric_get,
+            .metric_get_or_create = rrddim_metric_get_or_create,
+            .metric_dup = rrddim_metric_dup,
+            .metric_release = rrddim_metric_release,
             .collect_ops = im_collect_ops,
             .query_ops = im_query_ops
         }
@@ -78,13 +91,18 @@ static STORAGE_ENGINE engines[] = {
         .id = RRD_MEMORY_MODE_DBENGINE,
         .name = RRD_MEMORY_MODE_DBENGINE_NAME,
         .api = {
-            .init = rrdeng_metric_init,
-            .free = rrdeng_metric_free,
+            .metric_get = rrdeng_metric_get,
+            .metric_get_or_create = rrdeng_metric_get_or_create,
+            .metric_dup = rrdeng_metric_dup,
+            .metric_release = rrdeng_metric_release,
             .collect_ops = {
                 .init = rrdeng_store_metric_init,
                 .store_metric = rrdeng_store_metric_next,
                 .flush = rrdeng_store_metric_flush_current_page,
-                .finalize = rrdeng_store_metric_finalize
+                .finalize = rrdeng_store_metric_finalize,
+                .change_collection_frequency = rrdeng_store_metric_change_collection_frequency,
+                .metrics_group_get = rrdeng_metrics_group_get,
+                .metrics_group_release = rrdeng_metrics_group_release,
             },
             .query_ops = {
                 .init = rrdeng_load_metric_init,
diff --git a/database/storage_engine.h b/database/storage_engine.h
index 3ed515e0a..b7fb7383a 100644
--- a/database/storage_engine.h
+++ b/database/storage_engine.h
@@ -5,28 +5,8 @@
 
 #include "rrd.h"
 
-typedef struct storage_engine STORAGE_ENGINE;
-
-// ------------------------------------------------------------------------
-// function pointers for all APIs provided by a storge engine
-typedef struct storage_engine_api {
-    STORAGE_METRIC_HANDLE *(*init)(RRDDIM *rd, STORAGE_INSTANCE *instance);
-    void (*free)(STORAGE_METRIC_HANDLE *);
-    struct rrddim_collect_ops collect_ops;
-    struct rrddim_query_ops query_ops;
-} STORAGE_ENGINE_API;
-
-struct storage_engine {
-    RRD_MEMORY_MODE id;
-    const char* name;
-    STORAGE_ENGINE_API api;
-};
-
-extern STORAGE_ENGINE* storage_engine_get(RRD_MEMORY_MODE mmode);
-extern STORAGE_ENGINE* storage_engine_find(const char* name);
-
 // Iterator over existing engines
-extern STORAGE_ENGINE* storage_engine_foreach_init();
-extern STORAGE_ENGINE* storage_engine_foreach_next(STORAGE_ENGINE* it);
+STORAGE_ENGINE* storage_engine_foreach_init();
+STORAGE_ENGINE* storage_engine_foreach_next(STORAGE_ENGINE* it);
 
 #endif