Merging upstream version 1.39.0.

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

13 files changed, 1329 insertions, 1389 deletions

diff --git a/database/sqlite/sqlite_aclk.c b/database/sqlite/sqlite_aclk.c
index 3b0c40522..a33e09f5d 100644
--- a/database/sqlite/sqlite_aclk.c
+++ b/database/sqlite/sqlite_aclk.c
@@ -5,58 +5,176 @@
 
 #include "sqlite_aclk_node.h"
 
+struct aclk_sync_config_s {
+    uv_thread_t thread;
+    uv_loop_t loop;
+    uv_timer_t timer_req;
+    time_t cleanup_after;          // Start a cleanup after this timestamp
+    uv_async_t async;
+    /* FIFO command queue */
+    uv_mutex_t cmd_mutex;
+    uv_cond_t cmd_cond;
+    bool initialized;
+    volatile unsigned queue_size;
+    struct aclk_database_cmdqueue cmd_queue;
+} aclk_sync_config = { 0 };
+
+
 void sanity_check(void) {
     // make sure the compiler will stop on misconfigurations
     BUILD_BUG_ON(WORKER_UTILIZATION_MAX_JOB_TYPES < ACLK_MAX_ENUMERATIONS_DEFINED);
 }
 
-static int sql_check_aclk_table(void *data, int argc, char **argv, char **column)
+
+int aclk_database_enq_cmd_noblock(struct aclk_database_cmd *cmd)
 {
-    struct aclk_database_worker_config *wc = data;
-    UNUSED(argc);
-    UNUSED(column);
+    unsigned queue_size;
 
-    debug(D_ACLK_SYNC,"Scheduling aclk sync table check for node %s", (char *) argv[0]);
-    struct aclk_database_cmd cmd;
-    memset(&cmd, 0, sizeof(cmd));
-    cmd.opcode = ACLK_DATABASE_DELETE_HOST;
-    cmd.data = strdupz((char *) argv[0]);
-    aclk_database_enq_cmd_noblock(wc, &cmd);
+    /* wait for free space in queue */
+    uv_mutex_lock(&aclk_sync_config.cmd_mutex);
+    if ((queue_size = aclk_sync_config.queue_size) == ACLK_DATABASE_CMD_Q_MAX_SIZE) {
+        uv_mutex_unlock(&aclk_sync_config.cmd_mutex);
+        return 1;
+    }
+
+    fatal_assert(queue_size < ACLK_DATABASE_CMD_Q_MAX_SIZE);
+    /* enqueue command */
+    aclk_sync_config.cmd_queue.cmd_array[aclk_sync_config.cmd_queue.tail] = *cmd;
+    aclk_sync_config.cmd_queue.tail = aclk_sync_config.cmd_queue.tail != ACLK_DATABASE_CMD_Q_MAX_SIZE - 1 ?
+                                          aclk_sync_config.cmd_queue.tail + 1 : 0;
+    aclk_sync_config.queue_size = queue_size + 1;
+    uv_mutex_unlock(&aclk_sync_config.cmd_mutex);
     return 0;
 }
 
-#define SQL_SELECT_ACLK_ACTIVE_LIST "SELECT REPLACE(SUBSTR(name,19),'_','-') FROM sqlite_schema " \
-        "WHERE name LIKE 'aclk_chart_latest_%' AND type IN ('table');"
-
-static void sql_check_aclk_table_list(struct aclk_database_worker_config *wc)
+static void aclk_database_enq_cmd(struct aclk_database_cmd *cmd)
 {
-    char *err_msg = NULL;
-    debug(D_ACLK_SYNC,"Cleaning tables for nodes that do not exist");
-    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);
+    unsigned queue_size;
+
+    /* wait for free space in queue */
+    uv_mutex_lock(&aclk_sync_config.cmd_mutex);
+    while ((queue_size = aclk_sync_config.queue_size) == ACLK_DATABASE_CMD_Q_MAX_SIZE) {
+        uv_cond_wait(&aclk_sync_config.cmd_cond, &aclk_sync_config.cmd_mutex);
     }
+    fatal_assert(queue_size < ACLK_DATABASE_CMD_Q_MAX_SIZE);
+    /* enqueue command */
+    aclk_sync_config.cmd_queue.cmd_array[aclk_sync_config.cmd_queue.tail] = *cmd;
+    aclk_sync_config.cmd_queue.tail = aclk_sync_config.cmd_queue.tail != ACLK_DATABASE_CMD_Q_MAX_SIZE - 1 ?
+                                          aclk_sync_config.cmd_queue.tail + 1 : 0;
+    aclk_sync_config.queue_size = queue_size + 1;
+    uv_mutex_unlock(&aclk_sync_config.cmd_mutex);
+
+    /* wake up event loop */
+    int rc = uv_async_send(&aclk_sync_config.async);
+    if (unlikely(rc))
+        debug(D_ACLK_SYNC, "Failed to wake up event loop");
 }
 
-static void sql_maint_aclk_sync_database(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
+enum {
+    IDX_HOST_ID,
+    IDX_HOSTNAME,
+    IDX_REGISTRY,
+    IDX_UPDATE_EVERY,
+    IDX_OS,
+    IDX_TIMEZONE,
+    IDX_TAGS,
+    IDX_HOPS,
+    IDX_MEMORY_MODE,
+    IDX_ABBREV_TIMEZONE,
+    IDX_UTC_OFFSET,
+    IDX_PROGRAM_NAME,
+    IDX_PROGRAM_VERSION,
+    IDX_ENTRIES,
+    IDX_HEALTH_ENABLED,
+};
+
+static int create_host_callback(void *data, int argc, char **argv, char **column)
 {
-    UNUSED(cmd);
+    int *number_of_chidren = data;
+    UNUSED(argc);
+    UNUSED(column);
 
-    debug(D_ACLK, "Checking database for %s", wc->host_guid);
+    char guid[UUID_STR_LEN];
+    uuid_unparse_lower(*(uuid_t *)argv[IDX_HOST_ID], guid);
 
-    BUFFER *sql = buffer_create(ACLK_SYNC_QUERY_SIZE, &netdata_buffers_statistics.buffers_sqlite);
+    struct rrdhost_system_info *system_info = callocz(1, sizeof(struct rrdhost_system_info));
+    __atomic_sub_fetch(&netdata_buffers_statistics.rrdhost_allocations_size, sizeof(struct rrdhost_system_info), __ATOMIC_RELAXED);
 
-    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));
+    system_info->hops = str2i((const char *) argv[IDX_HOPS]);
 
-    buffer_free(sql);
+    sql_build_host_system_info((uuid_t *)argv[IDX_HOST_ID], system_info);
+
+    RRDHOST *host = rrdhost_find_or_create(
+          (const char *) argv[IDX_HOSTNAME]
+        , (const char *) argv[IDX_REGISTRY]
+        , guid
+        , (const char *) argv[IDX_OS]
+        , (const char *) argv[IDX_TIMEZONE]
+        , (const char *) argv[IDX_ABBREV_TIMEZONE]
+        , (int32_t) (argv[IDX_UTC_OFFSET] ? str2uint32_t(argv[IDX_UTC_OFFSET], NULL) : 0)
+        , (const char *) argv[IDX_TAGS]
+        , (const char *) (argv[IDX_PROGRAM_NAME] ? argv[IDX_PROGRAM_NAME] : "unknown")
+        , (const char *) (argv[IDX_PROGRAM_VERSION] ? argv[IDX_PROGRAM_VERSION] : "unknown")
+        , argv[IDX_UPDATE_EVERY] ? str2i(argv[IDX_UPDATE_EVERY]) : 1
+        , argv[IDX_ENTRIES] ? str2i(argv[IDX_ENTRIES]) : 0
+        , 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->rrdlabels = sql_load_host_labels((uuid_t *)argv[IDX_HOST_ID]);
+
+    (*number_of_chidren)++;
+
+#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\"", rrdhost_hostname(host), host->machine_guid, node_str);
+#endif
+    return 0;
 }
 
+#ifdef ENABLE_ACLK
+static struct aclk_database_cmd aclk_database_deq_cmd(void)
+{
+    struct aclk_database_cmd ret;
+    unsigned queue_size;
 
-#define SQL_SELECT_HOST_BY_UUID  "SELECT host_id FROM host WHERE host_id = @host_id;"
+    uv_mutex_lock(&aclk_sync_config.cmd_mutex);
+    queue_size = aclk_sync_config.queue_size;
+    if (queue_size == 0) {
+        memset(&ret, 0, sizeof(ret));
+        ret.opcode = ACLK_DATABASE_NOOP;
+        ret.completion = NULL;
+
+    } else {
+        /* dequeue command */
+        ret = aclk_sync_config.cmd_queue.cmd_array[aclk_sync_config.cmd_queue.head];
+        if (queue_size == 1) {
+            aclk_sync_config.cmd_queue.head = aclk_sync_config.cmd_queue.tail = 0;
+        } else {
+            aclk_sync_config.cmd_queue.head = aclk_sync_config.cmd_queue.head != ACLK_DATABASE_CMD_Q_MAX_SIZE - 1 ?
+                                                  aclk_sync_config.cmd_queue.head + 1 : 0;
+        }
+        aclk_sync_config.queue_size = queue_size - 1;
+        /* wake up producers */
+        uv_cond_signal(&aclk_sync_config.cmd_cond);
+    }
+    uv_mutex_unlock(&aclk_sync_config.cmd_mutex);
 
+    return ret;
+}
+
+#define SQL_SELECT_HOST_BY_UUID  "SELECT host_id FROM host WHERE host_id = @host_id;"
 static int is_host_available(uuid_t *host_id)
 {
     sqlite3_stmt *res = NULL;
@@ -76,7 +194,7 @@ static int is_host_available(uuid_t *host_id)
 
     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 select node instance information");
+        error_report("Failed to bind host_id parameter to check host existence");
         goto failed;
     }
     rc = sqlite3_step_monitored(res);
@@ -89,15 +207,13 @@ failed:
 }
 
 // OPCODE: ACLK_DATABASE_DELETE_HOST
-void sql_delete_aclk_table_list(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
+static void sql_delete_aclk_table_list(char *host_guid)
 {
-    UNUSED(wc);
-    char uuid_str[GUID_LEN + 1];
-    char host_str[GUID_LEN + 1];
+    char uuid_str[UUID_STR_LEN];
+    char host_str[UUID_STR_LEN];
 
     int rc;
     uuid_t host_uuid;
-    char *host_guid = (char *)cmd.data;
 
     if (unlikely(!host_guid))
         return;
@@ -139,273 +255,67 @@ void sql_delete_aclk_table_list(struct aclk_database_worker_config *wc, struct a
     if (unlikely(rc != SQLITE_OK))
         error_report("Failed to finalize statement to clean up aclk tables, rc = %d", rc);
 
-    db_execute(buffer_tostring(sql));
+    rc = db_execute(db_meta, buffer_tostring(sql));
+    if (unlikely(rc))
+        error("Failed to drop unused ACLK tables");
 
 fail:
     buffer_free(sql);
 }
 
-uv_mutex_t aclk_async_lock;
-struct aclk_database_worker_config  *aclk_thread_head = NULL;
-
-int claimed()
+static int sql_check_aclk_table(void *data __maybe_unused, int argc __maybe_unused, char **argv __maybe_unused, char **column __maybe_unused)
 {
-    int rc;
-    rrdhost_aclk_state_lock(localhost);
-    rc = (localhost->aclk_state.claimed_id != NULL);
-    rrdhost_aclk_state_unlock(localhost);
-    return rc;
-}
-
-void aclk_add_worker_thread(struct aclk_database_worker_config *wc)
-{
-    if (unlikely(!wc))
-        return;
-
-    uv_mutex_lock(&aclk_async_lock);
-    if (unlikely(!wc->host)) {
-        wc->next = aclk_thread_head;
-        aclk_thread_head = wc;
-    }
-    uv_mutex_unlock(&aclk_async_lock);
+    debug(D_ACLK_SYNC,"Scheduling aclk sync table check for node %s", (char *) argv[0]);
+    struct aclk_database_cmd cmd;
+    memset(&cmd, 0, sizeof(cmd));
+    cmd.opcode = ACLK_DATABASE_DELETE_HOST;
+    cmd.param[0] = strdupz((char *) argv[0]);
+    aclk_database_enq_cmd_noblock(&cmd);
+    return 0;
 }
 
-void aclk_del_worker_thread(struct aclk_database_worker_config *wc)
-{
-    if (unlikely(!wc))
-        return;
-
-    uv_mutex_lock(&aclk_async_lock);
-    struct aclk_database_worker_config **tmp = &aclk_thread_head;
-    while (*tmp && (*tmp) != wc)
-        tmp = &(*tmp)->next;
-    if (*tmp)
-        *tmp = wc->next;
-    uv_mutex_unlock(&aclk_async_lock);
-}
+#define SQL_SELECT_ACLK_ACTIVE_LIST "SELECT REPLACE(SUBSTR(name,19),'_','-') FROM sqlite_schema " \
+        "WHERE name LIKE 'aclk_chart_latest_%' AND type IN ('table');"
 
-int aclk_worker_thread_exists(char *guid)
+static void sql_check_aclk_table_list(void)
 {
-    int rc = 0;
-    uv_mutex_lock(&aclk_async_lock);
-
-    struct aclk_database_worker_config *tmp = aclk_thread_head;
-
-    while (tmp && !rc) {
-        rc = strcmp(tmp->uuid_str, guid) == 0;
-        tmp = tmp->next;
+    char *err_msg = NULL;
+    debug(D_ACLK_SYNC,"Cleaning tables for nodes that do not exist");
+    int rc = sqlite3_exec_monitored(db_meta, SQL_SELECT_ACLK_ACTIVE_LIST, sql_check_aclk_table, NULL, &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);
     }
-    uv_mutex_unlock(&aclk_async_lock);
-    return rc;
 }
 
-void aclk_database_init_cmd_queue(struct aclk_database_worker_config *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));
-}
+#define SQL_ALERT_CLEANUP "DELETE FROM aclk_alert_%s WHERE date_submitted IS NOT NULL AND CAST(date_cloud_ack AS INT) < unixepoch()-%d;"
 
-int aclk_database_enq_cmd_noblock(struct aclk_database_worker_config *wc, struct aclk_database_cmd *cmd)
+static int sql_maint_aclk_sync_database(void *data __maybe_unused, int argc __maybe_unused, char **argv, char **column __maybe_unused)
 {
-    unsigned queue_size;
-
-    /* wait for free space in queue */
-    uv_mutex_lock(&wc->cmd_mutex);
-    if ((queue_size = wc->queue_size) == ACLK_DATABASE_CMD_Q_MAX_SIZE || wc->is_shutting_down) {
-        uv_mutex_unlock(&wc->cmd_mutex);
-        return 1;
-    }
-
-    fatal_assert(queue_size < ACLK_DATABASE_CMD_Q_MAX_SIZE);
-    /* enqueue command */
-    wc->cmd_queue.cmd_array[wc->cmd_queue.tail] = *cmd;
-    wc->cmd_queue.tail = wc->cmd_queue.tail != ACLK_DATABASE_CMD_Q_MAX_SIZE - 1 ?
-                         wc->cmd_queue.tail + 1 : 0;
-    wc->queue_size = queue_size + 1;
-    uv_mutex_unlock(&wc->cmd_mutex);
+    char sql[512];
+    snprintfz(sql,511, SQL_ALERT_CLEANUP, (char *) argv[0], ACLK_DELETE_ACK_ALERTS_INTERNAL);
+    if (unlikely(db_execute(db_meta, sql)))
+        error_report("Failed to clean stale ACLK alert entries");
     return 0;
 }
 
-void aclk_database_enq_cmd(struct aclk_database_worker_config *wc, struct aclk_database_cmd *cmd)
-{
-    unsigned queue_size;
-
-    /* wait for free space in queue */
-    uv_mutex_lock(&wc->cmd_mutex);
-    if (wc->is_shutting_down) {
-        uv_mutex_unlock(&wc->cmd_mutex);
-        return;
-    }
-    while ((queue_size = wc->queue_size) == ACLK_DATABASE_CMD_Q_MAX_SIZE) {
-        uv_cond_wait(&wc->cmd_cond, &wc->cmd_mutex);
-    }
-    fatal_assert(queue_size < ACLK_DATABASE_CMD_Q_MAX_SIZE);
-    /* enqueue command */
-    wc->cmd_queue.cmd_array[wc->cmd_queue.tail] = *cmd;
-    wc->cmd_queue.tail = wc->cmd_queue.tail != ACLK_DATABASE_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 */
-    int rc = uv_async_send(&wc->async);
-    if (unlikely(rc))
-        debug(D_ACLK_SYNC, "Failed to wake up event loop");
-}
-
-struct aclk_database_cmd aclk_database_deq_cmd(struct aclk_database_worker_config* wc)
-{
-    struct aclk_database_cmd ret;
-    unsigned queue_size;
 
-    uv_mutex_lock(&wc->cmd_mutex);
-    queue_size = wc->queue_size;
-    if (queue_size == 0 || wc->is_shutting_down) {
-        memset(&ret, 0, sizeof(ret));
-        ret.opcode = ACLK_DATABASE_NOOP;
-        ret.completion = NULL;
-        if (wc->is_shutting_down)
-            uv_cond_signal(&wc->cmd_cond);
-    } 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 != ACLK_DATABASE_CMD_Q_MAX_SIZE - 1 ?
-                                 wc->cmd_queue.head + 1 : 0;
-        }
-        wc->queue_size = queue_size - 1;
-        /* wake up producers */
-        uv_cond_signal(&wc->cmd_cond);
-    }
-    uv_mutex_unlock(&wc->cmd_mutex);
-
-    return ret;
-}
+#define SQL_SELECT_ACLK_ALERT_LIST "SELECT SUBSTR(name,12) FROM sqlite_schema WHERE name LIKE 'aclk_alert_%' AND type IN ('table');"
 
-struct aclk_database_worker_config *find_inactive_wc_by_node_id(char *node_id)
+static void sql_maint_aclk_sync_database_all(void)
 {
-    if (unlikely(!node_id))
-        return NULL;
-
-    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;
+    char *err_msg = NULL;
+    debug(D_ACLK_SYNC,"Cleaning tables for nodes that do not exist");
+    int rc = sqlite3_exec_monitored(db_meta, SQL_SELECT_ACLK_ALERT_LIST, sql_maint_aclk_sync_database, NULL, &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);
     }
-    uv_mutex_unlock(&aclk_async_lock);
-
-    return (wc);
 }
 
-void aclk_sync_exit_all()
-{
-    rrd_rdlock();
-    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);
-        }
-    }
-    rrd_unlock();
-
-    uv_mutex_lock(&aclk_async_lock);
-    struct aclk_database_worker_config *wc = aclk_thread_head;
-    while (wc) {
-        wc->is_shutting_down = 1;
-        wc = wc->next;
-    }
-    uv_mutex_unlock(&aclk_async_lock);
-}
-
-enum {
-    IDX_HOST_ID,
-    IDX_HOSTNAME,
-    IDX_REGISTRY,
-    IDX_UPDATE_EVERY,
-    IDX_OS,
-    IDX_TIMEZONE,
-    IDX_TAGS,
-    IDX_HOPS,
-    IDX_MEMORY_MODE,
-    IDX_ABBREV_TIMEZONE,
-    IDX_UTC_OFFSET,
-    IDX_PROGRAM_NAME,
-    IDX_PROGRAM_VERSION,
-    IDX_ENTRIES,
-    IDX_HEALTH_ENABLED,
-};
-
-static int create_host_callback(void *data, int argc, char **argv, char **column)
-{
-    UNUSED(data);
-    UNUSED(argc);
-    UNUSED(column);
-
-    char guid[UUID_STR_LEN];
-    uuid_unparse_lower(*(uuid_t *)argv[IDX_HOST_ID], guid);
-
-    struct rrdhost_system_info *system_info = callocz(1, sizeof(struct rrdhost_system_info));
-    __atomic_sub_fetch(&netdata_buffers_statistics.rrdhost_allocations_size, sizeof(struct rrdhost_system_info), __ATOMIC_RELAXED);
-
-    system_info->hops = str2i((const char *) argv[IDX_HOPS]);
-
-    sql_build_host_system_info((uuid_t *)argv[IDX_HOST_ID], system_info);
-
-    RRDHOST *host = rrdhost_find_or_create(
-          (const char *) argv[IDX_HOSTNAME]
-        , (const char *) argv[IDX_REGISTRY]
-        , guid
-        , (const char *) argv[IDX_OS]
-        , (const char *) argv[IDX_TIMEZONE]
-        , (const char *) argv[IDX_ABBREV_TIMEZONE]
-        , argv[IDX_UTC_OFFSET] ? str2uint32_t(argv[IDX_UTC_OFFSET]) : 0
-        , (const char *) argv[IDX_TAGS]
-        , (const char *) (argv[IDX_PROGRAM_NAME] ? argv[IDX_PROGRAM_NAME] : "unknown")
-        , (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
-        , 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->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\"", rrdhost_hostname(host), host->machine_guid, node_str);
-#endif
-    return 0;
-}
-
-#ifdef ENABLE_ACLK
-static int aclk_start_sync_thread(void *data, int argc, char **argv, char **column)
+static int aclk_config_parameters(void *data __maybe_unused, int argc __maybe_unused, char **argv, char **column __maybe_unused)
 {
     char uuid_str[GUID_LEN + 1];
-    UNUSED(data);
-    UNUSED(argc);
-    UNUSED(column);
-
     uuid_unparse_lower(*((uuid_t *) argv[0]), uuid_str);
 
     RRDHOST *host = rrdhost_find_by_guid(uuid_str);
@@ -415,156 +325,81 @@ static int aclk_start_sync_thread(void *data, int argc, char **argv, char **colu
     sql_create_aclk_table(host, (uuid_t *) argv[0], (uuid_t *) argv[1]);
     return 0;
 }
-#endif
-void sql_aclk_sync_init(void)
-{
-    char *err_msg = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE) {
-            return;
-        }
-        error_report("Database has not been initialized");
-        return;
-    }
-
-    info("Creating archived hosts");
-    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);
-    }
-
-#ifdef ENABLE_ACLK
-    fatal_assert(0 == uv_mutex_init(&aclk_async_lock));
-    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);
-        sqlite3_free(err_msg);
-    }
-    info("ACLK sync initialization completed");
-#endif
-}
 
 static void async_cb(uv_async_t *handle)
 {
     uv_stop(handle->loop);
     uv_update_time(handle->loop);
-    debug(D_ACLK_SYNC, "%s called, active=%d.", __func__, uv_is_active((uv_handle_t *)handle));
 }
 
 #define TIMER_PERIOD_MS (1000)
 
-static void timer_cb(uv_timer_t* handle)
+static void timer_cb(uv_timer_t *handle)
 {
     uv_stop(handle->loop);
     uv_update_time(handle->loop);
 
-#ifdef ENABLE_ACLK
-    struct aclk_database_worker_config *wc = handle->data;
+    struct aclk_sync_config_s *config = handle->data;
     struct aclk_database_cmd cmd;
     memset(&cmd, 0, sizeof(cmd));
-    cmd.opcode = ACLK_DATABASE_TIMER;
-    aclk_database_enq_cmd_noblock(wc, &cmd);
 
     time_t now =  now_realtime_sec();
 
-    if (wc->cleanup_after && wc->cleanup_after < now) {
+    if (config->cleanup_after && config->cleanup_after < now) {
         cmd.opcode = ACLK_DATABASE_CLEANUP;
-        if (!aclk_database_enq_cmd_noblock(wc, &cmd))
-            wc->cleanup_after += ACLK_DATABASE_CLEANUP_INTERVAL;
+        if (!aclk_database_enq_cmd_noblock(&cmd))
+            config->cleanup_after += ACLK_DATABASE_CLEANUP_INTERVAL;
     }
 
     if (aclk_connected) {
-        if (wc->alert_updates && !wc->pause_alert_updates) {
-            cmd.opcode = ACLK_DATABASE_PUSH_ALERT;
-            cmd.count = ACLK_MAX_ALERT_UPDATES;
-            aclk_database_enq_cmd_noblock(wc, &cmd);
-        }
+        cmd.opcode = ACLK_DATABASE_PUSH_ALERT;
+        aclk_database_enq_cmd_noblock(&cmd);
+
+        aclk_check_node_info_and_collectors();
     }
-#endif
 }
 
-static void aclk_database_worker(void *arg)
+static void aclk_synchronization(void *arg __maybe_unused)
 {
-    service_register(SERVICE_THREAD_TYPE_EVENT_LOOP, NULL, NULL, NULL, true);
+    struct aclk_sync_config_s *config = arg;
+    uv_thread_set_name_np(config->thread,  "ACLKSYNC");
     worker_register("ACLKSYNC");
+    service_register(SERVICE_THREAD_TYPE_EVENT_LOOP, NULL, NULL, NULL, true);
+
     worker_register_job_name(ACLK_DATABASE_NOOP,                 "noop");
-    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");
     worker_register_job_name(ACLK_DATABASE_DELETE_HOST,          "node delete");
-    worker_register_job_name(ACLK_DATABASE_NODE_INFO,            "node info");
-    worker_register_job_name(ACLK_DATABASE_NODE_COLLECTORS,      "node collectors");
+    worker_register_job_name(ACLK_DATABASE_NODE_STATE,           "node state");
     worker_register_job_name(ACLK_DATABASE_PUSH_ALERT,           "alert push");
     worker_register_job_name(ACLK_DATABASE_PUSH_ALERT_CONFIG,    "alert conf push");
+    worker_register_job_name(ACLK_DATABASE_PUSH_ALERT_CHECKPOINT,"alert checkpoint");
     worker_register_job_name(ACLK_DATABASE_PUSH_ALERT_SNAPSHOT,  "alert snapshot");
     worker_register_job_name(ACLK_DATABASE_QUEUE_REMOVED_ALERTS, "alerts check");
     worker_register_job_name(ACLK_DATABASE_TIMER,                "timer");
 
-    struct aclk_database_worker_config *wc = arg;
-    uv_loop_t *loop;
-    int ret;
-    enum aclk_database_opcode opcode;
-    uv_timer_t timer_req;
-    struct aclk_database_cmd cmd;
+    uv_loop_t *loop = &config->loop;
+    fatal_assert(0 == uv_loop_init(loop));
+    fatal_assert(0 == uv_async_init(loop, &config->async, async_cb));
 
-    char threadname[NETDATA_THREAD_NAME_MAX+1];
-    if (wc->host)
-        snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "ACLK[%s]", rrdhost_hostname(wc->host));
-    else {
-        snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "ACLK[%s]", wc->uuid_str);
-        threadname[11] = '\0';
-    }
-    uv_thread_set_name_np(wc->thread, threadname);
-
-    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;
+    fatal_assert(0 == uv_timer_init(loop, &config->timer_req));
+    config->timer_req.data = config;
+    fatal_assert(0 == uv_timer_start(&config->timer_req, timer_cb, TIMER_PERIOD_MS, TIMER_PERIOD_MS));
 
-    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, &timer_req);
-    if (ret) {
-        error("uv_timer_init(): %s", uv_strerror(ret));
-        goto error_after_timer_init;
-    }
-    timer_req.data = wc;
-    fatal_assert(0 == uv_timer_start(&timer_req, timer_cb, TIMER_PERIOD_MS, TIMER_PERIOD_MS));
-
-    wc->node_info_send = 1;
-    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));
+    info("Starting ACLK synchronization thread");
 
-    wc->startup_time = now_realtime_sec();
-    wc->cleanup_after = wc->startup_time + ACLK_DATABASE_CLEANUP_FIRST;
+    config->cleanup_after = now_realtime_sec() + ACLK_DATABASE_CLEANUP_FIRST;
+    config->initialized = true;
 
-    debug(D_ACLK_SYNC,"Node %s reports pending message count = %u", wc->node_id, wc->chart_payload_count);
-
-    while (likely(!netdata_exit)) {
+    while (likely(service_running(SERVICE_ACLKSYNC))) {
+        enum aclk_database_opcode opcode;
         worker_is_idle();
         uv_run(loop, UV_RUN_DEFAULT);
 
         /* wait for commands */
         do {
-            cmd = aclk_database_deq_cmd(wc);
+            struct aclk_database_cmd cmd = aclk_database_deq_cmd();
 
-            if (netdata_exit)
+            if (unlikely(!service_running(SERVICE_ACLKSYNC)))
                 break;
 
             opcode = cmd.opcode;
@@ -576,201 +411,216 @@ static void aclk_database_worker(void *arg)
                 case ACLK_DATABASE_NOOP:
                     /* the command queue was empty, do nothing */
                     break;
-
 // 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);
+                    // Scan all aclk_alert_ tables and cleanup as needed
+                    sql_maint_aclk_sync_database_all();
+                    sql_check_aclk_table_list();
                     break;
 
                 case ACLK_DATABASE_DELETE_HOST:
-                    debug(D_ACLK_SYNC,"Cleaning ACLK tables for %s", (char *) cmd.data);
-                    sql_delete_aclk_table_list(wc, cmd);
+                    sql_delete_aclk_table_list(cmd.param[0]);
+                    break;
+// NODE STATE
+                case ACLK_DATABASE_NODE_STATE:;
+                    RRDHOST *host = cmd.param[0];
+                    int live = (host == localhost || host->receiver || !(rrdhost_flag_check(host, RRDHOST_FLAG_ORPHAN))) ? 1 : 0;
+                    struct aclk_sync_host_config *ahc = host->aclk_sync_host_config;
+                    if (unlikely(!ahc))
+                        sql_create_aclk_table(host, &host->host_uuid, host->node_id);
+                    aclk_host_state_update(host, live);
                     break;
-
 // ALERTS
                 case ACLK_DATABASE_PUSH_ALERT_CONFIG:
-                    debug(D_ACLK_SYNC,"Pushing chart config info to the cloud for %s", wc->host_guid);
-                    aclk_push_alert_config_event(wc, cmd);
+                    aclk_push_alert_config_event(cmd.param[0], cmd.param[1]);
                     break;
                 case ACLK_DATABASE_PUSH_ALERT:
-                    debug(D_ACLK_SYNC, "Pushing alert info to the cloud for %s", wc->host_guid);
-                    aclk_push_alert_event(wc, cmd);
-                    break;
-                case ACLK_DATABASE_ALARM_HEALTH_LOG:
-                    debug(D_ACLK_SYNC, "Pushing alarm health log to the cloud for %s", wc->host_guid);
-                    aclk_push_alarm_health_log(wc, cmd);
+                    aclk_push_alert_events_for_all_hosts();
                     break;
-                case ACLK_DATABASE_PUSH_ALERT_SNAPSHOT:
-                    debug(D_ACLK_SYNC, "Pushing alert snapshot to the cloud for node %s", wc->host_guid);
-                    aclk_push_alert_snapshot_event(wc, cmd);
+                case ACLK_DATABASE_PUSH_ALERT_SNAPSHOT:;
+                    aclk_push_alert_snapshot_event(cmd.param[0]);
                     break;
                 case ACLK_DATABASE_QUEUE_REMOVED_ALERTS:
-                    debug(D_ACLK_SYNC, "Queueing removed alerts for node %s", wc->host_guid);
-                    sql_process_queue_removed_alerts_to_aclk(wc, cmd);
-                    break;
-
-// NODE OPERATIONS
-                case ACLK_DATABASE_NODE_INFO:
-                    debug(D_ACLK_SYNC,"Sending node info for %s", wc->uuid_str);
-                    sql_build_node_info(wc, cmd);
-                    break;
-                case ACLK_DATABASE_NODE_COLLECTORS:
-                    debug(D_ACLK_SYNC,"Sending node collectors info for %s", wc->uuid_str);
-                    sql_build_node_collectors(wc);
-                    break;
-#ifdef ENABLE_ACLK
-
-// NODE_INSTANCE DETECTION
-                case ACLK_DATABASE_ORPHAN_HOST:
-                    wc->host = NULL;
-                    wc->is_orphan = 1;
-                    aclk_add_worker_thread(wc);
-                    break;
-#endif
-                case ACLK_DATABASE_TIMER:
-                    if (unlikely(localhost && !wc->host && !wc->is_orphan)) {
-                        if (claimed()) {
-                            wc->host = rrdhost_find_by_guid(wc->host_guid);
-                            if (wc->host) {
-                                info("HOST %s (%s) detected as active", rrdhost_hostname(wc->host), wc->host_guid);
-                                snprintfz(threadname, NETDATA_THREAD_NAME_MAX, "ACLK[%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(rrdhost_hostname(wc->host));
-                                aclk_del_worker_thread(wc);
-                                wc->node_info_send = 1;
-                            }
-                        }
-                    }
-                    if (wc->node_info_send && localhost && claimed() && aclk_connected) {
-                        cmd.opcode = ACLK_DATABASE_NODE_INFO;
-                        cmd.completion = NULL;
-                        wc->node_info_send = aclk_database_enq_cmd_noblock(wc, &cmd);
-                    }
-                    if (wc->node_collectors_send && wc->node_collectors_send + 30 < now_realtime_sec()) {
-                        cmd.opcode = ACLK_DATABASE_NODE_COLLECTORS;
-                        cmd.completion = NULL;
-                        wc->node_collectors_send = aclk_database_enq_cmd_noblock(wc, &cmd);
-                    }
-                    if (localhost == wc->host)
-                        (void) sqlite3_wal_checkpoint(db_meta, NULL);
+                    sql_process_queue_removed_alerts_to_aclk(cmd.param[0]);
                     break;
                 default:
                     debug(D_ACLK_SYNC, "%s: default.", __func__);
                     break;
             }
             if (cmd.completion)
-                aclk_complete(cmd.completion);
+                completion_mark_complete(cmd.completion);
         } while (opcode != ACLK_DATABASE_NOOP);
     }
 
-    if (!uv_timer_stop(&timer_req))
-        uv_close((uv_handle_t *)&timer_req, NULL);
-
-    /* cleanup operations of the event loop */
-    //info("Shutting down ACLK sync event loop for %s", wc->host_guid);
+    if (!uv_timer_stop(&config->timer_req))
+        uv_close((uv_handle_t *)&config->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_close((uv_handle_t *)&config->async, NULL);
+//    uv_close((uv_handle_t *)&config->async_exit, NULL);
+    uv_cond_destroy(&config->cmd_cond);
+    (void) uv_loop_close(loop);
 
-    info("Shutting down ACLK sync event loop complete for host %s", wc->host_guid);
-    /* TODO: don't let the API block by waiting to enqueue commands */
-    uv_cond_destroy(&wc->cmd_cond);
-
-    int rc;
-    do {
-        rc = uv_loop_close(loop);
-    } while (rc != UV_EBUSY);
-
-    freez(loop);
+    worker_unregister();
+    service_exits();
+    info("ACLK SYNC: Shutting down ACLK synchronization event loop");
+}
 
-    rrd_rdlock();
-    if (likely(wc->host))
-        wc->host->dbsync_worker = NULL;
-    freez(wc->hostname);
-    freez(wc);
-    rrd_unlock();
+static void aclk_synchronization_init(void)
+{
+    aclk_sync_config.cmd_queue.head = aclk_sync_config.cmd_queue.tail = 0;
+    aclk_sync_config.queue_size = 0;
+    fatal_assert(0 == uv_cond_init(&aclk_sync_config.cmd_cond));
+    fatal_assert(0 == uv_mutex_init(&aclk_sync_config.cmd_mutex));
 
-    worker_unregister();
-    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();
+    fatal_assert(0 == uv_thread_create(&aclk_sync_config.thread, aclk_synchronization, &aclk_sync_config));
 }
+#endif
 
 // -------------------------------------------------------------
 
-void sql_create_aclk_table(RRDHOST *host, uuid_t *host_uuid, uuid_t *node_id)
+void sql_create_aclk_table(RRDHOST *host __maybe_unused, uuid_t *host_uuid __maybe_unused, uuid_t *node_id __maybe_unused)
 {
 #ifdef ENABLE_ACLK
     char uuid_str[GUID_LEN + 1];
     char host_guid[GUID_LEN + 1];
+    int rc;
 
     uuid_unparse_lower_fix(host_uuid, uuid_str);
-
-    if (aclk_worker_thread_exists(uuid_str))
-        return;
-
     uuid_unparse_lower(*host_uuid, host_guid);
 
-    BUFFER *sql = buffer_create(ACLK_SYNC_QUERY_SIZE, &netdata_buffers_statistics.buffers_sqlite);
+    char sql[ACLK_SYNC_QUERY_SIZE];
 
-    buffer_sprintf(sql, TABLE_ACLK_ALERT, uuid_str);
-    db_execute(buffer_tostring(sql));
-    buffer_flush(sql);
-
-    buffer_sprintf(sql, INDEX_ACLK_ALERT, uuid_str, uuid_str);
-    db_execute(buffer_tostring(sql));
-
-    buffer_free(sql);
+    snprintfz(sql, ACLK_SYNC_QUERY_SIZE-1, TABLE_ACLK_ALERT, uuid_str);
+    rc = db_execute(db_meta, sql);
+    if (unlikely(rc))
+        error_report("Failed to create ACLK alert table for host %s", host ? rrdhost_hostname(host) : host_guid);
+    else {
+        snprintfz(sql, ACLK_SYNC_QUERY_SIZE -1, INDEX_ACLK_ALERT, uuid_str, uuid_str);
+        rc = db_execute(db_meta, sql);
+        if (unlikely(rc))
+            error_report("Failed to create ACLK alert table index for host %s", host ? string2str(host->hostname) : host_guid);
+    }
+    if (likely(host) && unlikely(host->aclk_sync_host_config))
+        return;
 
-    if (likely(host) && unlikely(host->dbsync_worker))
+    if (unlikely(!host))
         return;
 
-    struct aclk_database_worker_config *wc = callocz(1, sizeof(struct aclk_database_worker_config));
+    struct aclk_sync_host_config *wc = callocz(1, sizeof(struct aclk_sync_host_config));
     if (node_id && !uuid_is_null(*node_id))
         uuid_unparse_lower(*node_id, wc->node_id);
-    if (likely(host)) {
-        host->dbsync_worker = (void *)wc;
-        wc->hostname = strdupz(rrdhost_hostname(host));
-        if (node_id && !host->node_id) {
-            host->node_id = mallocz(sizeof(*host->node_id));
-            uuid_copy(*host->node_id, *node_id);
-        }
+
+    host->aclk_sync_host_config = (void *)wc;
+    if (node_id && !host->node_id) {
+        host->node_id = mallocz(sizeof(*host->node_id));
+        uuid_copy(*host->node_id, *node_id);
     }
-    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->alert_updates = 0;
-    aclk_database_init_cmd_queue(wc);
-    aclk_add_worker_thread(wc);
-    fatal_assert(0 == uv_thread_create(&(wc->thread), aclk_database_worker, wc));
-#else
-    UNUSED(host);
-    UNUSED(host_uuid);
-    UNUSED(node_id);
+    time_t now = now_realtime_sec();
+    wc->node_info_send_time = (host == localhost || NULL == localhost) ? now - 25 : now;
 #endif
-}
\ No newline at end of file
+}
+
+#define SQL_FETCH_ALL_HOSTS "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;"
+
+#define SQL_FETCH_ALL_INSTANCES "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; "
+void sql_aclk_sync_init(void)
+{
+    char *err_msg = NULL;
+    int rc;
+
+    if (unlikely(!db_meta)) {
+        if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE) {
+            return;
+        }
+        error_report("Database has not been initialized");
+        return;
+    }
+
+    info("Creating archived hosts");
+    int number_of_children = 0;
+    rc = sqlite3_exec_monitored(db_meta, SQL_FETCH_ALL_HOSTS, create_host_callback, &number_of_children, &err_msg);
+
+    if (rc != SQLITE_OK) {
+        error_report("SQLite error when loading archived hosts, rc = %d (%s)", rc, err_msg);
+        sqlite3_free(err_msg);
+    }
+
+    info("Created %d archived hosts", number_of_children);
+    // Trigger host context load for hosts that have been created
+    metadata_queue_load_host_context(NULL);
+
+#ifdef ENABLE_ACLK
+    if (!number_of_children)
+        aclk_queue_node_info(localhost, true);
+
+    rc = sqlite3_exec_monitored(db_meta, SQL_FETCH_ALL_INSTANCES,aclk_config_parameters, NULL,&err_msg);
+
+    if (rc != SQLITE_OK) {
+        error_report("SQLite error when configuring host ACLK synchonization parameters, rc = %d (%s)", rc, err_msg);
+        sqlite3_free(err_msg);
+    }
+    aclk_synchronization_init();
+
+    info("ACLK sync initialization completed");
+#endif
+}
+
+// Public
+
+static inline void queue_aclk_sync_cmd(enum aclk_database_opcode opcode, const void *param0, const void *param1)
+{
+    struct aclk_database_cmd cmd;
+    cmd.opcode = opcode;
+    cmd.param[0] = (void *) param0;
+    cmd.param[1] = (void *) param1;
+    cmd.completion = NULL;
+    aclk_database_enq_cmd(&cmd);
+}
+
+// Public
+void aclk_push_alert_config(const char *node_id, const char *config_hash)
+{
+    if (unlikely(!aclk_sync_config.initialized))
+        return;
+
+    queue_aclk_sync_cmd(ACLK_DATABASE_PUSH_ALERT_CONFIG, strdupz(node_id), strdupz(config_hash));
+}
+
+void aclk_push_node_alert_snapshot(const char *node_id)
+{
+    if (unlikely(!aclk_sync_config.initialized))
+        return;
+
+    queue_aclk_sync_cmd(ACLK_DATABASE_PUSH_ALERT_SNAPSHOT, strdupz(node_id), NULL);
+}
+
+
+void aclk_push_node_removed_alerts(const char *node_id)
+{
+    if (unlikely(!aclk_sync_config.initialized))
+        return;
+
+    queue_aclk_sync_cmd(ACLK_DATABASE_QUEUE_REMOVED_ALERTS, strdupz(node_id), NULL);
+}
+
+void schedule_node_info_update(RRDHOST *host __maybe_unused)
+{
+#ifdef ENABLE_ACLK
+    if (unlikely(!host))
+        return;
+
+    struct aclk_database_cmd cmd;
+    memset(&cmd, 0, sizeof(cmd));
+    cmd.opcode = ACLK_DATABASE_NODE_STATE;
+    cmd.param[0] = host;
+    cmd.completion = NULL;
+    aclk_database_enq_cmd(&cmd);
+#endif
+}
diff --git a/database/sqlite/sqlite_aclk.h b/database/sqlite/sqlite_aclk.h
index 208177e45..d555a0cef 100644
--- a/database/sqlite/sqlite_aclk.h
+++ b/database/sqlite/sqlite_aclk.h
@@ -18,45 +18,6 @@
 #define ACLK_DELETE_ACK_ALERTS_INTERNAL (86400)
 #define ACLK_SYNC_QUERY_SIZE 512
 
-struct aclk_completion {
-    uv_mutex_t mutex;
-    uv_cond_t cond;
-    volatile unsigned completed;
-};
-
-static inline void init_aclk_completion(struct aclk_completion *p)
-{
-    p->completed = 0;
-    fatal_assert(0 == uv_cond_init(&p->cond));
-    fatal_assert(0 == uv_mutex_init(&p->mutex));
-}
-
-static inline void destroy_aclk_completion(struct aclk_completion *p)
-{
-    uv_cond_destroy(&p->cond);
-    uv_mutex_destroy(&p->mutex);
-}
-
-static inline void wait_for_aclk_completion(struct aclk_completion *p)
-{
-    uv_mutex_lock(&p->mutex);
-    while (0 == p->completed) {
-        uv_cond_wait(&p->cond, &p->mutex);
-    }
-    fatal_assert(1 == p->completed);
-    uv_mutex_unlock(&p->mutex);
-}
-
-static inline void aclk_complete(struct aclk_completion *p)
-{
-    uv_mutex_lock(&p->mutex);
-    p->completed = 1;
-    uv_mutex_unlock(&p->mutex);
-    uv_cond_broadcast(&p->cond);
-}
-
-extern uv_mutex_t aclk_async_lock;
-
 static inline void uuid_unparse_lower_fix(uuid_t *uuid, char *out)
 {
     uuid_unparse_lower(*uuid, out);
@@ -66,6 +27,12 @@ static inline void uuid_unparse_lower_fix(uuid_t *uuid, char *out)
     out[23] = '_';
 }
 
+static inline int claimed()
+{
+    return localhost->aclk_state.claimed_id != NULL;
+}
+
+
 #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, filtered_alert_unique_id NOT NULL, " \
         "unique(alert_unique_id));"
@@ -74,16 +41,14 @@ static inline void uuid_unparse_lower_fix(uuid_t *uuid, char *out)
 enum aclk_database_opcode {
     ACLK_DATABASE_NOOP = 0,
 
-    ACLK_DATABASE_ORPHAN_HOST,
-    ACLK_DATABASE_ALARM_HEALTH_LOG,
     ACLK_DATABASE_CLEANUP,
     ACLK_DATABASE_DELETE_HOST,
-    ACLK_DATABASE_NODE_INFO,
+    ACLK_DATABASE_NODE_STATE,
     ACLK_DATABASE_PUSH_ALERT,
     ACLK_DATABASE_PUSH_ALERT_CONFIG,
     ACLK_DATABASE_PUSH_ALERT_SNAPSHOT,
+    ACLK_DATABASE_PUSH_ALERT_CHECKPOINT,
     ACLK_DATABASE_QUEUE_REMOVED_ALERTS,
-    ACLK_DATABASE_NODE_COLLECTORS,
     ACLK_DATABASE_TIMER,
 
     // leave this last
@@ -93,10 +58,8 @@ enum aclk_database_opcode {
 
 struct aclk_database_cmd {
     enum aclk_database_opcode opcode;
-    void *data;
-    void *data_param;
-    int count;
-    struct aclk_completion *completion;
+    void *param[2];
+    struct completion *completion;
 };
 
 #define ACLK_DATABASE_CMD_Q_MAX_SIZE (1024)
@@ -106,67 +69,27 @@ struct aclk_database_cmdqueue {
     struct aclk_database_cmd cmd_array[ACLK_DATABASE_CMD_Q_MAX_SIZE];
 };
 
-struct aclk_database_worker_config {
-    uv_thread_t thread;
-    char uuid_str[GUID_LEN + 1];
-    char node_id[GUID_LEN + 1];
-    char host_guid[GUID_LEN + 1];
-    char *hostname;                 // hostname to avoid constant lookups
-    time_t cleanup_after;           // Start a cleanup after this timestamp
-    time_t startup_time;           // When the sync thread started
-    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
-    int pause_alert_updates;
-    uint32_t chart_payload_count;
-    uint64_t alerts_snapshot_id; //will contain the snapshot_id value if snapshot was requested
-    uint64_t alerts_ack_sequence_id; //last sequence_id ack'ed from cloud via sendsnapshot message
-    uv_loop_t *loop;
+struct aclk_sync_host_config {
     RRDHOST *host;
-    uv_async_t async;
-    /* FIFO command queue */
-    uv_mutex_t cmd_mutex;
-    uv_cond_t cmd_cond;
-    volatile unsigned queue_size;
-    struct aclk_database_cmdqueue cmd_queue;
     int alert_updates;
-    int node_info_send;
+    int alert_checkpoint_req;
+    int alert_queue_removed;
+    time_t node_info_send_time;
     time_t node_collectors_send;
-    volatile unsigned is_shutting_down;
-    volatile unsigned is_orphan;
-    struct aclk_database_worker_config  *next;
+    char uuid_str[UUID_STR_LEN];
+    char node_id[UUID_STR_LEN];
+    char *alerts_snapshot_uuid;        // will contain the snapshot_uuid value if snapshot was requested
 };
 
-static inline RRDHOST *find_host_by_node_id(char *node_id)
-{
-    uuid_t node_uuid;
-    if (unlikely(!node_id))
-        return NULL;
-
-    if (uuid_parse(node_id, node_uuid))
-        return NULL;
-
-    rrd_rdlock();
-    RRDHOST *host, *ret = NULL;
-    rrdhost_foreach_read(host) {
-        if (host->node_id && !(uuid_compare(*host->node_id, node_uuid))) {
-            ret = host;
-            break;
-        }
-    }
-    rrd_unlock();
-
-    return ret;
-}
-
-
 extern sqlite3 *db_meta;
 
-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);
+int aclk_database_enq_cmd_noblock(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);
-int claimed();
-void aclk_sync_exit_all();
-struct aclk_database_worker_config *find_inactive_wc_by_node_id(char *node_id);
+void aclk_push_alert_config(const char *node_id, const char *config_hash);
+void aclk_push_node_alert_snapshot(const char *node_id);
+void aclk_push_node_health_log(const char *node_id);
+void aclk_push_node_removed_alerts(const char *node_id);
+void schedule_node_info_update(RRDHOST *host);
+
 #endif //NETDATA_SQLITE_ACLK_H
diff --git a/database/sqlite/sqlite_aclk_alert.c b/database/sqlite/sqlite_aclk_alert.c
index ce284ebc3..62f1df29d 100644
--- a/database/sqlite/sqlite_aclk_alert.c
+++ b/database/sqlite/sqlite_aclk_alert.c
@@ -5,20 +5,20 @@
 
 #ifdef ENABLE_ACLK
 #include "../../aclk/aclk_alarm_api.h"
-#include "../../aclk/aclk.h"
 #endif
 
+#define SQL_GET_ALERT_REMOVE_TIME "SELECT when_key FROM health_log_%s WHERE alarm_id = %u " \
+                                  "AND unique_id > %u AND unique_id < %u " \
+                                  "AND new_status = -2;"
+
 time_t removed_when(uint32_t alarm_id, uint32_t before_unique_id, uint32_t after_unique_id, char *uuid_str) {
     sqlite3_stmt *res = NULL;
-    int rc = 0;
     time_t when = 0;
     char sql[ACLK_SYNC_QUERY_SIZE];
 
-    snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, "select when_key from health_log_%s where alarm_id = %u " \
-                                          "and unique_id > %u and unique_id < %u " \
-                                          "and new_status = -2;", uuid_str, alarm_id, after_unique_id, before_unique_id);
+    snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, SQL_GET_ALERT_REMOVE_TIME, uuid_str, alarm_id, after_unique_id, before_unique_id);
 
-    rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
+    int rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
     if (rc != SQLITE_OK) {
         error_report("Failed to prepare statement when trying to find removed gap.");
         return 0;
@@ -36,22 +36,26 @@ time_t removed_when(uint32_t alarm_id, uint32_t before_unique_id, uint32_t after
     return when;
 }
 
+#define SQL_UPDATE_FILTERED_ALERT "UPDATE aclk_alert_%s SET filtered_alert_unique_id = %u where filtered_alert_unique_id = %u"
+
 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);
+    snprintfz(sql, ACLK_SYNC_QUERY_SIZE-1, SQL_UPDATE_FILTERED_ALERT, uuid_str, ae->unique_id, unique_id);
     sqlite3_exec_monitored(db_meta, sql, 0, 0, NULL);
     ae->flags |= HEALTH_ENTRY_FLAG_ACLK_QUEUED;
 }
 
+#define SQL_SELECT_ALERT_BY_UNIQUE_ID "SELECT hl.unique_id FROM health_log_%s hl, alert_hash ah WHERE hl.unique_id = %u " \
+                            "AND hl.config_hash_id = ah.hash_id " \
+                            "AND ah.warn IS NULL AND ah.crit IS NULL;"
+
 static inline bool is_event_from_alert_variable_config(uint32_t unique_id, char *uuid_str) {
     sqlite3_stmt *res = NULL;
     int rc = 0;
     bool ret = false;
 
     char sql[ACLK_SYNC_QUERY_SIZE];
-    snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, "select hl.unique_id from health_log_%s hl, alert_hash ah where hl.unique_id = %u " \
-                                          "and hl.config_hash_id = ah.hash_id " \
-                                          "and ah.warn is null and ah.crit is null;", uuid_str, unique_id);
+    snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, SQL_SELECT_ALERT_BY_UNIQUE_ID, uuid_str, unique_id);
 
     rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
     if (rc != SQLITE_OK) {
@@ -73,12 +77,18 @@ static inline bool is_event_from_alert_variable_config(uint32_t unique_id, char
 
 #define MAX_REMOVED_PERIOD 86400
 //decide if some events should be sent or not
+
+#define SQL_SELECT_ALERT_BY_ID  "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.filtered_alert_unique_id " \
+                                "AND hl.alarm_id = %u " \
+                                "ORDER BY alarm_event_id DESC LIMIT 1;"
+
 int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
 {
     sqlite3_stmt *res = NULL;
-    char uuid_str[GUID_LEN + 1];
+    char uuid_str[UUID_STR_LEN];
     uuid_unparse_lower_fix(&host->host_uuid, uuid_str);
-    int send = 1, rc = 0;
+    int send = 1;
 
     if (ae->new_status == RRDCALC_STATUS_REMOVED || ae->new_status == RRDCALC_STATUS_UNINITIALIZED) {
         return 0;
@@ -87,9 +97,6 @@ int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
     if (unlikely(uuid_is_null(ae->config_hash_id))) 
         return 0;
 
-    if (is_event_from_alert_variable_config(ae->unique_id, uuid_str))
-        return 0;
-
     char sql[ACLK_SYNC_QUERY_SIZE];
     uuid_t config_hash_id;
     RRDCALC_STATUS status;
@@ -97,12 +104,9 @@ int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
 
     //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.filtered_alert_unique_id \
-                         and hl.alarm_id = %u \
-                         order by alarm_event_id desc LIMIT 1;", uuid_str, uuid_str, ae->alarm_id);
+    snprintfz(sql,ACLK_SYNC_QUERY_SIZE-1, SQL_SELECT_ALERT_BY_ID, uuid_str, uuid_str, ae->alarm_id);
 
-    rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
+    int rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
     if (rc != SQLITE_OK) {
         error_report("Failed to prepare statement when trying to filter alert events.");
         send = 1;
@@ -126,7 +130,7 @@ int should_send_to_cloud(RRDHOST *host, ALARM_ENTRY *ae)
         goto done;
     }
 
-    if (uuid_compare(ae->config_hash_id, config_hash_id)) {
+    if (uuid_memcmp(&ae->config_hash_id, &config_hash_id)) {
         send = 1;
         goto done;
     }
@@ -162,6 +166,10 @@ done:
 
 // will replace call to aclk_update_alarm in health/health_log.c
 // and handle both cases
+
+#define SQL_QUEUE_ALERT_TO_CLOUD "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;"
+
 int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter)
 {
     if(!service_running(SERVICE_ACLK))
@@ -182,27 +190,24 @@ int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter)
         }
     }
 
-    int rc = 0;
-    sqlite3_stmt *res_alert = NULL;
-    char uuid_str[GUID_LEN + 1];
+    char uuid_str[UUID_STR_LEN];
     uuid_unparse_lower_fix(&host->host_uuid, uuid_str);
 
-    BUFFER *sql = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+    if (is_event_from_alert_variable_config(ae->unique_id, uuid_str))
+        return 0;
+
+    sqlite3_stmt *res_alert = NULL;
+    char sql[ACLK_SYNC_QUERY_SIZE];
 
-    buffer_sprintf(
-        sql,
-        "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);
+    snprintfz(sql, ACLK_SYNC_QUERY_SIZE - 1, SQL_QUEUE_ALERT_TO_CLOUD, uuid_str);
 
-    rc = sqlite3_prepare_v2(db_meta, buffer_tostring(sql), -1, &res_alert, 0);
+    int rc = sqlite3_prepare_v2(db_meta, sql, -1, &res_alert, 0);
     if (unlikely(rc != SQLITE_OK)) {
         error_report("Failed to prepare statement to store alert event");
-        buffer_free(sql);
         return 1;
     }
 
-    rc = sqlite3_bind_int(res_alert, 1, ae->unique_id);
+    rc = sqlite3_bind_int(res_alert, 1, (int) ae->unique_id);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
@@ -213,16 +218,12 @@ int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter)
     }
 
     ae->flags |= HEALTH_ENTRY_FLAG_ACLK_QUEUED;
-    struct aclk_database_worker_config *wc  = (struct aclk_database_worker_config *)host->dbsync_worker;
-    if (wc) {
-        wc->pause_alert_updates = 0;
-    }
+    rrdhost_flag_set(host, RRDHOST_FLAG_ACLK_STREAM_ALERTS);
 
 bind_fail:
     if (unlikely(sqlite3_finalize(res_alert) != SQLITE_OK))
         error_report("Failed to reset statement in store alert event, rc = %d", rc);
 
-    buffer_free(sql);
     return 0;
 }
 
@@ -254,11 +255,10 @@ int rrdcalc_status_to_proto_enum(RRDCALC_STATUS status)
 #endif
 }
 
-void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
+void aclk_push_alert_event(struct aclk_sync_host_config *wc)
 {
 #ifndef ENABLE_ACLK
     UNUSED(wc);
-    UNUSED(cmd);
 #else
     int rc;
 
@@ -278,26 +278,7 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
 
     BUFFER *sql = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
 
-    if (wc->alerts_start_seq_id != 0) {
-        buffer_sprintf(
-            sql,
-            "UPDATE aclk_alert_%s SET date_submitted = NULL, date_cloud_ack = NULL WHERE sequence_id >= %"PRIu64
-            "; UPDATE aclk_alert_%s SET date_cloud_ack = unixepoch() WHERE sequence_id < %"PRIu64
-            " and date_cloud_ack is null "
-            "; UPDATE aclk_alert_%s SET date_submitted = unixepoch() WHERE sequence_id < %"PRIu64
-            " and date_submitted is null",
-            wc->uuid_str,
-            wc->alerts_start_seq_id,
-            wc->uuid_str,
-            wc->alerts_start_seq_id,
-            wc->uuid_str,
-            wc->alerts_start_seq_id);
-        db_execute(buffer_tostring(sql));
-        buffer_reset(sql);
-        wc->alerts_start_seq_id = 0;
-    }
-
-    int limit = cmd.count > 0 ? cmd.count : 1;
+    int limit = ACLK_MAX_ALERT_UPDATES;
 
     sqlite3_stmt *res = NULL;
 
@@ -318,10 +299,15 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
 
         BUFFER *sql_fix = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
         buffer_sprintf(sql_fix, TABLE_ACLK_ALERT, wc->uuid_str);
-        db_execute(buffer_tostring(sql_fix));
-        buffer_flush(sql_fix);
-        buffer_sprintf(sql_fix, INDEX_ACLK_ALERT, wc->uuid_str, wc->uuid_str);
-        db_execute(buffer_tostring(sql_fix));
+        rc = db_execute(db_meta, buffer_tostring(sql_fix));
+        if (unlikely(rc))
+            error_report("Failed to create ACLK alert table for host %s", rrdhost_hostname(wc->host));
+        else {
+            buffer_flush(sql_fix);
+            buffer_sprintf(sql_fix, INDEX_ACLK_ALERT, wc->uuid_str, wc->uuid_str);
+            if (unlikely(db_execute(db_meta, buffer_tostring(sql_fix))))
+                error_report("Failed to create ACLK alert table for host %s", rrdhost_hostname(wc->host));
+        }
         buffer_free(sql_fix);
 
         // Try again
@@ -353,8 +339,8 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
         alarm_log.name = strdupz((char *)sqlite3_column_text(res, 11));
         alarm_log.family = sqlite3_column_bytes(res, 13) > 0 ? strdupz((char *)sqlite3_column_text(res, 13)) : NULL;
 
-        alarm_log.batch_id = wc->alerts_batch_id;
-        alarm_log.sequence_id = (uint64_t) sqlite3_column_int64(res, 0);
+        //alarm_log.batch_id = wc->alerts_batch_id;
+        //alarm_log.sequence_id = (uint64_t) sqlite3_column_int64(res, 0);
         alarm_log.when = (time_t) sqlite3_column_int64(res, 5);
 
         uuid_unparse_lower(*((uuid_t *) sqlite3_column_blob(res, 3)), uuid_str);
@@ -429,19 +415,23 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
         buffer_sprintf(sql, "UPDATE aclk_alert_%s SET date_submitted=unixepoch() "
                             "WHERE date_submitted IS NULL AND sequence_id BETWEEN %" PRIu64 " AND %" PRIu64 ";",
                        wc->uuid_str, first_sequence_id, last_sequence_id);
-        db_execute(buffer_tostring(sql));
+
+        if (unlikely(db_execute(db_meta, buffer_tostring(sql))))
+            error_report("Failed to mark ACLK alert entries as submitted for host %s", rrdhost_hostname(wc->host));
+
+        // Mark to do one more check
+        rrdhost_flag_set(wc->host, RRDHOST_FLAG_ACLK_STREAM_ALERTS);
+
     } else {
         if (log_first_sequence_id)
             log_access(
-                "ACLK RES [%s (%s)]: ALERTS SENT from %" PRIu64 " to %" PRIu64 " batch=%" PRIu64,
+                "ACLK RES [%s (%s)]: ALERTS SENT from %" PRIu64 " to %" PRIu64 "",
                 wc->node_id,
                 wc->host ? rrdhost_hostname(wc->host) : "N/A",
                 log_first_sequence_id,
-                log_last_sequence_id,
-                wc->alerts_batch_id);
+                log_last_sequence_id);
         log_first_sequence_id = 0;
         log_last_sequence_id = 0;
-        wc->pause_alert_updates = 1;
     }
 
     rc = sqlite3_finalize(res);
@@ -451,8 +441,24 @@ void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_d
     freez(claim_id);
     buffer_free(sql);
 #endif
+}
+
+void aclk_push_alert_events_for_all_hosts(void)
+{
+    RRDHOST *host;
+
+    dfe_start_reentrant(rrdhost_root_index, host) {
+        if (rrdhost_flag_check(host, RRDHOST_FLAG_ARCHIVED) || !rrdhost_flag_check(host, RRDHOST_FLAG_ACLK_STREAM_ALERTS))
+            continue;
 
-    return;
+        internal_error(true, "ACLK SYNC: Scanning host %s", rrdhost_hostname(host));
+        rrdhost_flag_clear(host, RRDHOST_FLAG_ACLK_STREAM_ALERTS);
+
+        struct aclk_sync_host_config *wc = host->aclk_sync_host_config;
+        if (likely(wc))
+            aclk_push_alert_event(wc);
+    }
+    dfe_done(host);
 }
 
 void sql_queue_existing_alerts_to_aclk(RRDHOST *host)
@@ -467,137 +473,15 @@ void sql_queue_existing_alerts_to_aclk(RRDHOST *host)
                        "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);
 
-    db_execute(buffer_tostring(sql));
-
-    buffer_free(sql);
-
-    struct aclk_database_worker_config *wc  = (struct aclk_database_worker_config *)host->dbsync_worker;
-    if (wc) {
-        wc->pause_alert_updates = 0;
-    }
-}
-
-void aclk_send_alarm_health_log(char *node_id)
-{
-    if (unlikely(!node_id))
-        return;
-
-    struct aclk_database_worker_config *wc = find_inactive_wc_by_node_id(node_id);
-
-    if (likely(!wc)) {
-        RRDHOST *host = find_host_by_node_id(node_id);
-        if (likely(host))
-            wc = (struct aclk_database_worker_config *)host->dbsync_worker;
-    }
-
-    if (!wc) {
-        log_access("ACLK REQ [%s (N/A)]: HEALTH LOG REQUEST RECEIVED FOR INVALID NODE", node_id);
-        return;
-    }
-
-    log_access("ACLK REQ [%s (%s)]: HEALTH LOG REQUEST RECEIVED", node_id, wc->hostname ? wc->hostname : "N/A");
-
-    struct aclk_database_cmd cmd;
-    memset(&cmd, 0, sizeof(cmd));
-    cmd.opcode = ACLK_DATABASE_ALARM_HEALTH_LOG;
-
-    aclk_database_enq_cmd(wc, &cmd);
-    return;
-}
-
-void aclk_push_alarm_health_log(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    UNUSED(cmd);
-#ifndef ENABLE_ACLK
-    UNUSED(wc);
-#else
-    int rc;
-
-    char *claim_id = get_agent_claimid();
-    if (unlikely(!claim_id))
-        return;
-
-    RRDHOST *host = wc->host;
-    if (unlikely(!host)) {
-        host = find_host_by_node_id(wc->node_id);
-
-        if (unlikely(!host)) {
-            log_access(
-                "AC [%s (N/A)]: ACLK synchronization thread for %s is not yet linked to HOST.",
-                wc->node_id,
-                wc->host_guid);
-            freez(claim_id);
-            return;
-        }
-    }
-
-    uint64_t first_sequence = 0;
-    uint64_t last_sequence = 0;
-    struct timeval first_timestamp;
-    struct timeval last_timestamp;
-
-    BUFFER *sql = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
-
-    sqlite3_stmt *res = NULL;
-
-    //TODO: make this better: include info from health log too
-    buffer_sprintf(sql, "SELECT MIN(sequence_id), MIN(date_created), MAX(sequence_id), MAX(date_created) " \
-         "FROM aclk_alert_%s;", wc->uuid_str);
-
-    rc = sqlite3_prepare_v2(db_meta, buffer_tostring(sql), -1, &res, 0);
-    if (rc != SQLITE_OK) {
-        error_report("Failed to prepare statement to get health log statistics from the database");
-        buffer_free(sql);
-        freez(claim_id);
-        return;
-    }
-
-    first_timestamp.tv_sec = 0;
-    first_timestamp.tv_usec = 0;
-    last_timestamp.tv_sec = 0;
-    last_timestamp.tv_usec = 0;
-
-    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);
-        }
-
-        last_sequence = sqlite3_column_bytes(res, 2) > 0 ? (uint64_t) sqlite3_column_int64(res, 2) : 0;
-        if (sqlite3_column_bytes(res, 3) > 0) {
-            last_timestamp.tv_sec = sqlite3_column_int64(res, 3);
-        }
-    }
-
-    struct alarm_log_entries log_entries;
-    log_entries.first_seq_id = first_sequence;
-    log_entries.first_when = first_timestamp;
-    log_entries.last_seq_id = last_sequence;
-    log_entries.last_when = last_timestamp;
-
-    struct alarm_log_health alarm_log;
-    alarm_log.claim_id = claim_id;
-    alarm_log.node_id =  wc->node_id;
-    alarm_log.log_entries = log_entries;
-    alarm_log.status = wc->alert_updates == 0 ? 2 : 1;
-    alarm_log.enabled = (int)host->health.health_enabled;
-
-    wc->alert_sequence_id = last_sequence;
+    netdata_rwlock_rdlock(&host->health_log.alarm_log_rwlock);
 
-    aclk_send_alarm_log_health(&alarm_log);
-    log_access("ACLK RES [%s (%s)]: HEALTH LOG SENT from %"PRIu64" to %"PRIu64, wc->node_id, wc->hostname ? wc->hostname : "N/A", first_sequence, last_sequence);
+    if (unlikely(db_execute(db_meta, buffer_tostring(sql))))
+        error_report("Failed to queue existing ACLK alert events for host %s", rrdhost_hostname(host));
 
-    rc = sqlite3_finalize(res);
-    if (unlikely(rc != SQLITE_OK))
-        error_report("Failed to reset statement to get health log statistics from the database, rc = %d", rc);
+    netdata_rwlock_unlock(&host->health_log.alarm_log_rwlock);
 
-    freez(claim_id);
     buffer_free(sql);
-
-    aclk_alert_reloaded = 1;
-#endif
-
-    return;
+    rrdhost_flag_set(host, RRDHOST_FLAG_ACLK_STREAM_ALERTS);
 }
 
 void aclk_send_alarm_configuration(char *config_hash)
@@ -605,22 +489,14 @@ void aclk_send_alarm_configuration(char *config_hash)
     if (unlikely(!config_hash))
         return;
 
-    struct aclk_database_worker_config *wc = (struct aclk_database_worker_config *) localhost->dbsync_worker;
+    struct aclk_sync_host_config *wc = (struct aclk_sync_host_config *) localhost->aclk_sync_host_config;
 
-    if (unlikely(!wc)) {
+    if (unlikely(!wc))
         return;
-    }
 
     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));
-    cmd.opcode = ACLK_DATABASE_PUSH_ALERT_CONFIG;
-    cmd.data_param = (void *) strdupz(config_hash);
-    cmd.completion = NULL;
-    aclk_database_enq_cmd(wc, &cmd);
-
-    return;
+    aclk_push_alert_config(wc->node_id, config_hash);
 }
 
 #define SQL_SELECT_ALERT_CONFIG "SELECT alarm, template, on_key, class, type, component, os, hosts, plugin," \
@@ -628,19 +504,31 @@ void aclk_send_alarm_configuration(char *config_hash)
     "options, host_labels, p_db_lookup_dimensions, p_db_lookup_method, p_db_lookup_options, p_db_lookup_after," \
     "p_db_lookup_before, p_update_every FROM alert_hash WHERE hash_id = @hash_id;"
 
-int aclk_push_alert_config_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
+int aclk_push_alert_config_event(char *node_id __maybe_unused, char *config_hash __maybe_unused)
 {
-    UNUSED(wc);
-#ifndef ENABLE_ACLK
-    UNUSED(cmd);
-#else
     int rc = 0;
 
+#ifdef ENABLE_ACLK
+
     CHECK_SQLITE_CONNECTION(db_meta);
 
     sqlite3_stmt *res = NULL;
 
-    char *config_hash = (char *) cmd.data_param;
+    struct aclk_sync_host_config *wc = NULL;
+    RRDHOST *host = find_host_by_node_id(node_id);
+
+    if (unlikely(!host)) {
+        freez(config_hash);
+        freez(node_id);
+        return 1;
+    }
+
+    wc = (struct aclk_sync_host_config *)host->aclk_sync_host_config;
+    if (unlikely(!wc)) {
+        freez(config_hash);
+        freez(node_id);
+        return 1;
+    }
 
     rc = sqlite3_prepare_v2(db_meta, SQL_SELECT_ALERT_CONFIG, -1, &res, 0);
     if (rc != SQLITE_OK) {
@@ -723,7 +611,6 @@ 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 ? 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);
     }
@@ -735,150 +622,125 @@ bind_fail:
     if (unlikely(rc != SQLITE_OK))
         error_report("Failed to reset statement when pushing alarm config hash, rc = %d", rc);
 
-    return rc;
+    freez(config_hash);
+    freez(node_id);
 #endif
-    return 0;
+    return rc;
 }
 
 
 // Start streaming alerts
-void aclk_start_alert_streaming(char *node_id, uint64_t batch_id, uint64_t start_seq_id)
+void aclk_start_alert_streaming(char *node_id, bool resets)
 {
     if (unlikely(!node_id))
         return;
 
-    //log_access("ACLK REQ [%s (N/A)]: ALERTS STREAM from %"PRIu64" batch=%"PRIu64".", node_id, start_seq_id, batch_id);
-
     uuid_t node_uuid;
     if (uuid_parse(node_id, node_uuid))
         return;
 
-    struct aclk_database_worker_config *wc  = NULL;
     RRDHOST *host = find_host_by_node_id(node_id);
-    if (likely(host)) {
-        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 (unlikely(!host->health.health_enabled)) {
-            log_access("ACLK STA [%s (N/A)]: Ignoring request to stream alert state changes, health is disabled.", node_id);
-            return;
-        }
+    if (unlikely(!host))
+        return;
 
-        if (unlikely(batch_id == 1) && unlikely(start_seq_id == 1))
-            sql_queue_existing_alerts_to_aclk(host);
-    } else
-        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 ? 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;
-        wc->alert_updates = 1;
-        wc->pause_alert_updates = 0;
-        __sync_synchronize();
+    struct aclk_sync_host_config *wc  = host->aclk_sync_host_config;
+
+    if (unlikely(!wc))
+        return;
+
+    if (unlikely(!host->health.health_enabled)) {
+        log_access("ACLK STA [%s (N/A)]: Ignoring request to stream alert state changes, health is disabled.", node_id);
+        return;
     }
-    else
-        log_access("ACLK STA [%s (N/A)]: ACLK synchronization thread is not active.", node_id);
 
-    return;
+    if (resets) {
+        log_access("ACLK REQ [%s (%s)]: STREAM ALERTS ENABLED (RESET REQUESTED)", node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A");
+        sql_queue_existing_alerts_to_aclk(host);
+    } else
+        log_access("ACLK REQ [%s (%s)]: STREAM ALERTS ENABLED", node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A");
+
+    wc->alert_updates = 1;
+    wc->alert_queue_removed = SEND_REMOVED_AFTER_HEALTH_LOOPS;
 }
 
-void sql_process_queue_removed_alerts_to_aclk(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
-{
-    UNUSED(cmd);
+#define SQL_QUEUE_REMOVE_ALERTS "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) " \
+                                "AND config_hash_id NOT IN (select hash_id from alert_hash where warn is null and crit is null) " \
+                                "ORDER BY unique_id ASC " \
+                                "ON CONFLICT (alert_unique_id) DO NOTHING;"
 
-    BUFFER *sql = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+void sql_process_queue_removed_alerts_to_aclk(char *node_id)
+{
+    struct aclk_sync_host_config *wc;
+    RRDHOST *host = find_host_by_node_id(node_id);
+    freez(node_id);
 
-    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);
+    if (unlikely(!host || !(wc = host->aclk_sync_host_config)))
+        return;
 
-    db_execute(buffer_tostring(sql));
+    char sql[ACLK_SYNC_QUERY_SIZE * 2];
 
-    log_access("ACLK STA [%s (%s)]: QUEUED REMOVED ALERTS", wc->node_id, wc->host ? rrdhost_hostname(wc->host) : "N/A");
+    snprintfz(sql,ACLK_SYNC_QUERY_SIZE * 2 - 1, SQL_QUEUE_REMOVE_ALERTS, wc->uuid_str, wc->uuid_str, wc->uuid_str);
 
-    buffer_free(sql);
+    if (unlikely(db_execute(db_meta, sql))) {
+        log_access("ACLK STA [%s (%s)]: QUEUED REMOVED ALERTS FAILED", wc->node_id, rrdhost_hostname(wc->host));
+        error_report("Failed to queue ACLK alert removed entries for host %s", rrdhost_hostname(wc->host));
+    }
+    else
+        log_access("ACLK STA [%s (%s)]: QUEUED REMOVED ALERTS", wc->node_id, rrdhost_hostname(wc->host));
 
-    wc->pause_alert_updates = 0;
-    return;
+    rrdhost_flag_set(wc->host, RRDHOST_FLAG_ACLK_STREAM_ALERTS);
+    wc->alert_queue_removed = 0;
 }
 
 void sql_queue_removed_alerts_to_aclk(RRDHOST *host)
 {
-    if (unlikely(!host->dbsync_worker))
+    if (unlikely(!host->aclk_sync_host_config))
         return;
 
-    if (!claimed())
+    if (!claimed() || !host->node_id)
         return;
 
-    struct aclk_database_cmd cmd;
-    memset(&cmd, 0, sizeof(cmd));
-    cmd.opcode = ACLK_DATABASE_QUEUE_REMOVED_ALERTS;
-    cmd.data = NULL;
-    cmd.data_param = NULL;
-    cmd.completion = NULL;
-    aclk_database_enq_cmd((struct aclk_database_worker_config *) host->dbsync_worker, &cmd);
+    char node_id[UUID_STR_LEN];
+    uuid_unparse_lower(*host->node_id, node_id);
+
+    aclk_push_node_removed_alerts(node_id);
 }
 
-void aclk_process_send_alarm_snapshot(char *node_id, char *claim_id, uint64_t snapshot_id, uint64_t sequence_id)
+void aclk_process_send_alarm_snapshot(char *node_id, char *claim_id __maybe_unused, char *snapshot_uuid)
 {
-    UNUSED(claim_id);
-    if (unlikely(!node_id))
-        return;
-
     uuid_t node_uuid;
-    if (uuid_parse(node_id, node_uuid))
+    if (unlikely(!node_id || uuid_parse(node_id, node_uuid)))
         return;
 
-    struct aclk_database_worker_config *wc = NULL;
     RRDHOST *host = find_host_by_node_id(node_id);
-    if (likely(host))
-        wc = (struct aclk_database_worker_config *)host->dbsync_worker;
-
-    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 ? rrdhost_hostname(wc->host) : "N/A",
-            snapshot_id,
-            sequence_id);
-        if (wc->alerts_snapshot_id == snapshot_id)
-            return;
-        __sync_synchronize();
-        wc->alerts_snapshot_id = snapshot_id;
-        wc->alerts_ack_sequence_id = sequence_id;
-        __sync_synchronize();
-
-        struct aclk_database_cmd cmd;
-        memset(&cmd, 0, sizeof(cmd));
-        cmd.opcode = ACLK_DATABASE_PUSH_ALERT_SNAPSHOT;
-        cmd.data_param = NULL;
-        cmd.completion = NULL;
-        aclk_database_enq_cmd(wc, &cmd);
-    } else
-        log_access("ACLK STA [%s (N/A)]: ACLK synchronization thread is not active.", node_id);
-
-    return;
-}
+    if (unlikely(!host)) {
+        log_access("ACLK STA [%s (N/A)]: ACLK node id does not exist", node_id);
+        return;
+    }
 
-void aclk_mark_alert_cloud_ack(char *uuid_str, uint64_t alerts_ack_sequence_id)
-{
-    BUFFER *sql = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+    struct aclk_sync_host_config *wc = (struct aclk_sync_host_config *)host->aclk_sync_host_config;
 
-    if (alerts_ack_sequence_id != 0) {
-        buffer_sprintf(
-            sql,
-            "UPDATE aclk_alert_%s SET date_cloud_ack = unixepoch() WHERE sequence_id <= %" PRIu64 "",
-            uuid_str,
-            alerts_ack_sequence_id);
-        db_execute(buffer_tostring(sql));
+    if (unlikely(!wc)) {
+       log_access("ACLK STA [%s (N/A)]: ACLK node id does not exist", node_id);
+       return;
     }
 
-    buffer_free(sql);
+    log_access(
+            "IN [%s (%s)]: Request to send alerts snapshot, snapshot_uuid %s",
+            node_id,
+            wc->host ? rrdhost_hostname(wc->host) : "N/A",
+            snapshot_uuid);
+    if (wc->alerts_snapshot_uuid && !strcmp(wc->alerts_snapshot_uuid,snapshot_uuid))
+        return;
+    __sync_synchronize();
+    wc->alerts_snapshot_uuid = strdupz(snapshot_uuid);
+    __sync_synchronize();
+
+    aclk_push_node_alert_snapshot(node_id);
 }
 
 #ifdef ENABLE_ACLK
@@ -949,37 +811,41 @@ static int have_recent_alarm(RRDHOST *host, uint32_t alarm_id, uint32_t mark)
 #endif
 
 #define ALARM_EVENTS_PER_CHUNK 10
-void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
+void aclk_push_alert_snapshot_event(char *node_id __maybe_unused)
 {
-#ifndef ENABLE_ACLK
-    UNUSED(wc);
-    UNUSED(cmd);
-#else
-    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 ? rrdhost_hostname(wc->host) : "N/A");
+#ifdef ENABLE_ACLK
+    RRDHOST *host = find_host_by_node_id(node_id);
+
+    if (unlikely(!host)) {
+        log_access("AC [%s (N/A)]: Node id not found", node_id);
+        freez(node_id);
         return;
     }
+    freez(node_id);
 
-    if (unlikely(!wc->host)) {
-        error_report("ACLK synchronization thread for %s is not linked to HOST", wc->host_guid);
+    struct aclk_sync_host_config *wc = host->aclk_sync_host_config;
+
+    // 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 ? rrdhost_hostname(wc->host) : "N/A");
         return;
     }
 
-    if (unlikely(!wc->alerts_snapshot_id))
+    if (unlikely(!wc->alerts_snapshot_uuid))
         return;
 
     char *claim_id = get_agent_claimid();
     if (unlikely(!claim_id))
         return;
 
-    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);
+    log_access("ACLK REQ [%s (%s)]: Sending alerts snapshot, snapshot_uuid %s", wc->node_id, rrdhost_hostname(wc->host), wc->alerts_snapshot_uuid);
 
-    aclk_mark_alert_cloud_ack(wc->uuid_str, wc->alerts_ack_sequence_id);
-
-    RRDHOST *host = wc->host;
     uint32_t cnt = 0;
+    char uuid_str[UUID_STR_LEN];
+    uuid_unparse_lower_fix(&host->host_uuid, uuid_str);
 
     netdata_rwlock_rdlock(&host->health_log.alarm_log_rwlock);
 
@@ -995,6 +861,9 @@ void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, stru
         if (have_recent_alarm(host, ae->alarm_id, ae->unique_id))
             continue;
 
+        if (is_event_from_alert_variable_config(ae->unique_id, uuid_str))
+            continue;
+
         cnt++;
     }
 
@@ -1008,7 +877,7 @@ void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, stru
         struct alarm_snapshot alarm_snap;
         alarm_snap.node_id = wc->node_id;
         alarm_snap.claim_id = claim_id;
-        alarm_snap.snapshot_id = wc->alerts_snapshot_id;
+        alarm_snap.snapshot_uuid = wc->alerts_snapshot_uuid;
         alarm_snap.chunks = chunks;
         alarm_snap.chunk = chunk;
 
@@ -1024,6 +893,9 @@ void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, stru
             if (have_recent_alarm(host, ae->alarm_id, ae->unique_id))
                 continue;
 
+            if (is_event_from_alert_variable_config(ae->unique_id, uuid_str))
+                continue;
+
             cnt++;
 
             struct alarm_log_entry alarm_log;
@@ -1047,7 +919,7 @@ void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, stru
                     struct alarm_snapshot alarm_snap;
                     alarm_snap.node_id = wc->node_id;
                     alarm_snap.claim_id = claim_id;
-                    alarm_snap.snapshot_id = wc->alerts_snapshot_id;
+                    alarm_snap.snapshot_uuid = wc->alerts_snapshot_uuid;
                     alarm_snap.chunks = chunks;
                     alarm_snap.chunk = chunk;
 
@@ -1061,73 +933,204 @@ void aclk_push_alert_snapshot_event(struct aclk_database_worker_config *wc, stru
     }
 
     netdata_rwlock_unlock(&host->health_log.alarm_log_rwlock);
-    wc->alerts_snapshot_id = 0;
+    wc->alerts_snapshot_uuid = NULL;
 
     freez(claim_id);
 #endif
-    return;
 }
 
+#define SQL_DELETE_ALERT_ENTRIES "DELETE FROM aclk_alert_%s WHERE filtered_alert_unique_id NOT IN (SELECT unique_id FROM health_log_%s);"
+
 void sql_aclk_alert_clean_dead_entries(RRDHOST *host)
 {
     if (!claimed())
         return;
 
-    char uuid_str[GUID_LEN + 1];
+    char uuid_str[UUID_STR_LEN];
     uuid_unparse_lower_fix(&host->host_uuid, uuid_str);
 
-    BUFFER *sql = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+    char sql[512];
+    snprintfz(sql,511,SQL_DELETE_ALERT_ENTRIES, uuid_str, uuid_str);
 
-    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_monitored(db_meta, buffer_tostring(sql), NULL, NULL, &err_msg);
+    int rc = sqlite3_exec_monitored(db_meta, 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);
+        error_report("Failed when trying to clean stale ACLK alert entries from aclk_alert_%s, error message \"%s\"", uuid_str, err_msg);
         sqlite3_free(err_msg);
     }
-    buffer_free(sql);
 }
 
+#define SQL_GET_MIN_MAX_ALERT_SEQ "SELECT MIN(sequence_id), MAX(sequence_id), " \
+                                  "(SELECT MAX(sequence_id) FROM aclk_alert_%s WHERE date_submitted IS NOT NULL) " \
+                                  "FROM aclk_alert_%s WHERE date_submitted IS NULL;"
+
 int get_proto_alert_status(RRDHOST *host, struct proto_alert_status *proto_alert_status)
 {
     int rc;
-    struct aclk_database_worker_config *wc  = NULL;
-    wc = (struct aclk_database_worker_config *)host->dbsync_worker;
+    struct aclk_sync_host_config *wc  = NULL;
+    wc = (struct aclk_sync_host_config *)host->aclk_sync_host_config;
     if (!wc)
         return 1;
 
     proto_alert_status->alert_updates = wc->alert_updates;
-    proto_alert_status->alerts_batch_id = wc->alerts_batch_id;
 
-    BUFFER *sql = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+    char sql[ACLK_SYNC_QUERY_SIZE];
     sqlite3_stmt *res = NULL;
 
-    buffer_sprintf(sql, "SELECT MIN(sequence_id), MAX(sequence_id), " \
-                   "(select MAX(sequence_id) from aclk_alert_%s where date_cloud_ack is not NULL), " \
-                   "(select MAX(sequence_id) from aclk_alert_%s where date_submitted is not NULL) " \
-                   "FROM aclk_alert_%s where date_submitted is null;", wc->uuid_str, wc->uuid_str, wc->uuid_str);
+    snprintfz(sql, ACLK_SYNC_QUERY_SIZE - 1, SQL_GET_MIN_MAX_ALERT_SEQ, wc->uuid_str, wc->uuid_str);
 
-    rc = sqlite3_prepare_v2(db_meta, buffer_tostring(sql), -1, &res, 0);
+    rc = sqlite3_prepare_v2(db_meta, sql, -1, &res, 0);
     if (rc != SQLITE_OK) {
         error_report("Failed to prepare statement to get alert log status from the database.");
-        buffer_free(sql);
         return 1;
     }
 
     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;
-        proto_alert_status->last_submitted_sequence_id = sqlite3_column_bytes(res, 3) > 0 ? (uint64_t) sqlite3_column_int64(res, 3) : 0;
+        proto_alert_status->last_submitted_sequence_id = sqlite3_column_bytes(res, 2) > 0 ? (uint64_t) sqlite3_column_int64(res, 2) : 0;
     }
 
     rc = sqlite3_finalize(res);
     if (unlikely(rc != SQLITE_OK))
         error_report("Failed to finalize statement to get alert log status from the database, rc = %d", rc);
 
-    buffer_free(sql);
     return 0;
 }
+
+void aclk_send_alarm_checkpoint(char *node_id, char *claim_id __maybe_unused)
+{
+    if (unlikely(!node_id))
+        return;
+
+    struct aclk_sync_host_config *wc = NULL;
+    RRDHOST *host = find_host_by_node_id(node_id);
+
+    if (unlikely(!host))
+        return;
+
+    wc = (struct aclk_sync_host_config *)host->aclk_sync_host_config;
+    if (unlikely(!wc)) {
+        log_access("ACLK REQ [%s (N/A)]: ALERTS CHECKPOINT REQUEST RECEIVED FOR INVALID NODE", node_id);
+        return;
+    }
+
+    log_access("ACLK REQ [%s (%s)]: ALERTS CHECKPOINT REQUEST RECEIVED", node_id, rrdhost_hostname(host));
+
+    wc->alert_checkpoint_req = SEND_CHECKPOINT_AFTER_HEALTH_LOOPS;
+}
+
+typedef struct active_alerts {
+    char *name;
+    char *chart;
+    RRDCALC_STATUS status;
+} active_alerts_t;
+
+static inline int compare_active_alerts(const void * a, const void * b) {
+    active_alerts_t *active_alerts_a = (active_alerts_t *)a;
+    active_alerts_t *active_alerts_b = (active_alerts_t *)b;
+
+    if( !(strcmp(active_alerts_a->name, active_alerts_b->name)) )
+        {
+            return strcmp(active_alerts_a->chart, active_alerts_b->chart);
+        }
+    else
+        return strcmp(active_alerts_a->name, active_alerts_b->name);
+}
+
+void aclk_push_alarm_checkpoint(RRDHOST *host __maybe_unused)
+{
+#ifdef ENABLE_ACLK
+    struct aclk_sync_host_config *wc = host->aclk_sync_host_config;
+    if (unlikely(!wc)) {
+        log_access("ACLK REQ [%s (N/A)]: ALERTS CHECKPOINT REQUEST RECEIVED FOR INVALID NODE", rrdhost_hostname(host));
+        return;
+    }
+
+    //TODO: make sure all pending events are sent.
+    if (rrdhost_flag_check(host, RRDHOST_FLAG_ACLK_STREAM_ALERTS)) {
+        //postpone checkpoint send
+        wc->alert_checkpoint_req++;
+        log_access("ACLK REQ [%s (N/A)]: ALERTS CHECKPOINT POSTPONED", rrdhost_hostname(host));
+        return;
+    }
+
+    //TODO: lock rc here, or make sure it's called when health decides
+    //count them
+    RRDCALC *rc;
+    uint32_t cnt = 0;
+    size_t len = 0;
+    active_alerts_t *active_alerts = NULL;
+
+    foreach_rrdcalc_in_rrdhost_read(host, rc) {
+        if(unlikely(!rc->rrdset || !rc->rrdset->last_collected_time.tv_sec))
+            continue;
+
+        if (rc->status == RRDCALC_STATUS_WARNING ||
+            rc->status == RRDCALC_STATUS_CRITICAL) {
+
+            cnt++;
+        }
+    }
+    foreach_rrdcalc_in_rrdhost_done(rc);
+
+    if (cnt) {
+        active_alerts = callocz(cnt, sizeof(active_alerts_t));
+        cnt = 0;
+        foreach_rrdcalc_in_rrdhost_read(host, rc) {
+            if(unlikely(!rc->rrdset || !rc->rrdset->last_collected_time.tv_sec))
+                continue;
+
+            if (rc->status == RRDCALC_STATUS_WARNING ||
+                rc->status == RRDCALC_STATUS_CRITICAL) {
+
+                active_alerts[cnt].name = (char *)rrdcalc_name(rc);
+                len += string_strlen(rc->name);
+                active_alerts[cnt].chart = (char *)rrdcalc_chart_name(rc);
+                len += string_strlen(rc->chart);
+                active_alerts[cnt].status = rc->status;
+                len++;
+                cnt++;
+            }
+        }
+        foreach_rrdcalc_in_rrdhost_done(rc);
+    }
+
+    BUFFER *alarms_to_hash;
+    if (cnt) {
+        qsort (active_alerts, cnt, sizeof(active_alerts_t), compare_active_alerts);
+
+        alarms_to_hash = buffer_create(len, NULL);
+        for (uint32_t i=0;i<cnt;i++) {
+            buffer_strcat(alarms_to_hash, active_alerts[i].name);
+            buffer_strcat(alarms_to_hash, active_alerts[i].chart);
+            if (active_alerts[i].status == RRDCALC_STATUS_WARNING)
+                buffer_strcat(alarms_to_hash, "W");
+            else if (active_alerts[i].status == RRDCALC_STATUS_CRITICAL)
+                buffer_strcat(alarms_to_hash, "C");
+        }
+    } else {
+        alarms_to_hash = buffer_create(1, NULL);
+        buffer_strcat(alarms_to_hash, "");
+        len = 0;
+    }
+
+    char hash[SHA256_DIGEST_LENGTH + 1];
+    if (hash256_string((const unsigned char *)buffer_tostring(alarms_to_hash), len, hash)) {
+        hash[SHA256_DIGEST_LENGTH] = 0;
+
+        struct alarm_checkpoint alarm_checkpoint;
+        char *claim_id = get_agent_claimid();
+        alarm_checkpoint.claim_id = claim_id;
+        alarm_checkpoint.node_id = wc->node_id;
+        alarm_checkpoint.checksum = (char *)hash;
+
+        aclk_send_provide_alarm_checkpoint(&alarm_checkpoint);
+        log_access("ACLK RES [%s (%s)]: ALERTS CHECKPOINT SENT", wc->node_id, rrdhost_hostname(host));
+    } else {
+        log_access("ACLK RES [%s (%s)]: FAILED TO CREATE ALERTS CHECKPOINT HASH", wc->node_id, rrdhost_hostname(host));
+    }
+    wc->alert_checkpoint_req = 0;
+    buffer_free(alarms_to_hash);
+#endif
+}
diff --git a/database/sqlite/sqlite_aclk_alert.h b/database/sqlite/sqlite_aclk_alert.h
index 88a939e87..d7252aad6 100644
--- a/database/sqlite/sqlite_aclk_alert.h
+++ b/database/sqlite/sqlite_aclk_alert.h
@@ -5,27 +5,31 @@
 
 extern sqlite3 *db_meta;
 
+#define SEND_REMOVED_AFTER_HEALTH_LOOPS 3
+#define SEND_CHECKPOINT_AFTER_HEALTH_LOOPS 4
+
 struct proto_alert_status {
     int alert_updates;
-    uint64_t alerts_batch_id;
-    uint64_t last_acked_sequence_id;
     uint64_t pending_min_sequence_id;
     uint64_t pending_max_sequence_id;
     uint64_t last_submitted_sequence_id;
 };
 
-int aclk_add_alert_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void aclk_push_alert_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void aclk_send_alarm_health_log(char *node_id);
-void aclk_push_alarm_health_log(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
+int aclk_add_alert_event(struct aclk_sync_host_config *wc, struct aclk_database_cmd cmd);
+void aclk_push_alert_event(struct aclk_sync_host_config *wc);
 void aclk_send_alarm_configuration (char *config_hash);
-int aclk_push_alert_config_event(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void aclk_start_alert_streaming(char *node_id, uint64_t batch_id, uint64_t start_seq_id);
+int aclk_push_alert_config_event(char *node_id, char *config_hash);
+void aclk_start_alert_streaming(char *node_id, bool resets);
 void sql_queue_removed_alerts_to_aclk(RRDHOST *host);
-void sql_process_queue_removed_alerts_to_aclk(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-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);
+void sql_process_queue_removed_alerts_to_aclk(char *node_id);
+void aclk_send_alarm_checkpoint(char *node_id, char *claim_id);
+void aclk_push_alarm_checkpoint(RRDHOST *host);
+
+void aclk_push_alert_snapshot_event(char *node_id);
+void aclk_process_send_alarm_snapshot(char *node_id, char *claim_id, char *snapshot_uuid);
 int get_proto_alert_status(RRDHOST *host, struct proto_alert_status *proto_alert_status);
 int sql_queue_alarm_to_aclk(RRDHOST *host, ALARM_ENTRY *ae, int skip_filter);
+void aclk_push_alert_events_for_all_hosts(void);
+
 
 #endif //NETDATA_SQLITE_ACLK_ALERT_H
diff --git a/database/sqlite/sqlite_aclk_node.c b/database/sqlite/sqlite_aclk_node.c
index afe774997..3817296da 100644
--- a/database/sqlite/sqlite_aclk_node.c
+++ b/database/sqlite/sqlite_aclk_node.c
@@ -25,12 +25,17 @@ DICTIONARY *collectors_from_charts(RRDHOST *host, DICTIONARY *dict) {
 
     return dict;
 }
-#endif
 
-void sql_build_node_collectors(struct aclk_database_worker_config *wc)
+static void build_node_collectors(char *node_id __maybe_unused)
 {
-#ifdef ENABLE_ACLK
-    if (!wc->host)
+
+    RRDHOST *host = find_host_by_node_id(node_id);
+
+    if (unlikely(!host))
+        return;
+
+    struct aclk_sync_host_config *wc = (struct aclk_sync_host_config *) host->aclk_sync_host_config;
+    if (unlikely(!wc))
         return;
 
     struct update_node_collectors upd_node_collectors;
@@ -39,48 +44,51 @@ void sql_build_node_collectors(struct aclk_database_worker_config *wc)
     upd_node_collectors.node_id = wc->node_id;
     upd_node_collectors.claim_id = get_agent_claimid();
 
-    upd_node_collectors.node_collectors = collectors_from_charts(wc->host, dict);
+    upd_node_collectors.node_collectors = collectors_from_charts(host, dict);
     aclk_update_node_collectors(&upd_node_collectors);
 
     dictionary_destroy(dict);
     freez(upd_node_collectors.claim_id);
 
-    log_access("ACLK RES [%s (%s)]: NODE COLLECTORS SENT", wc->node_id, rrdhost_hostname(wc->host));
-#else
-    UNUSED(wc);
-#endif
-    return;
+    log_access("ACLK RES [%s (%s)]: NODE COLLECTORS SENT", node_id, rrdhost_hostname(host));
+
+    freez(node_id);
 }
 
-void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd)
+static void build_node_info(char *node_id __maybe_unused)
 {
-    UNUSED(cmd);
-
-#ifdef ENABLE_ACLK
     struct update_node_info node_info;
 
-    if (!wc->host) {
-        wc->node_info_send = 1;
+    RRDHOST *host = find_host_by_node_id(node_id);
+
+    if (unlikely((!host))) {
+        freez(node_id);
+        return;
+    }
+
+    struct aclk_sync_host_config *wc = (struct aclk_sync_host_config *) host->aclk_sync_host_config;
+
+    if (unlikely(!wc)) {
+        freez(node_id);
         return;
     }
 
     rrd_rdlock();
     node_info.node_id = wc->node_id;
     node_info.claim_id = get_agent_claimid();
-    node_info.machine_guid = wc->host_guid;
+    node_info.machine_guid = host->machine_guid;
     node_info.child = (wc->host != localhost);
-    node_info.ml_info.ml_capable = ml_capable(localhost);
+    node_info.ml_info.ml_capable = ml_capable();
     node_info.ml_info.ml_enabled = ml_enabled(wc->host);
 
     node_info.node_instance_capabilities = aclk_get_node_instance_capas(wc->host);
 
     now_realtime_timeval(&node_info.updated_at);
 
-    RRDHOST *host = wc->host;
     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 : rrdhost_program_version(host));
         netdata_mutex_unlock(&host->receiver_lock);
     }
 
@@ -91,7 +99,7 @@ void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_dat
     node_info.data.kernel_name = host->system_info->kernel_name;
     node_info.data.kernel_version = host->system_info->kernel_version;
     node_info.data.architecture = host->system_info->architecture;
-    node_info.data.cpus = host->system_info->host_cores ? str2uint32_t(host->system_info->host_cores) : 0;
+    node_info.data.cpus = host->system_info->host_cores ? str2uint32_t(host->system_info->host_cores, NULL) : 0;
     node_info.data.cpu_frequency = host->system_info->host_cpu_freq ? host->system_info->host_cpu_freq : "0";
     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";
@@ -101,7 +109,7 @@ void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_dat
     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", "");
-    node_info.data.machine_guid = wc->host_guid;
+    node_info.data.machine_guid = host->machine_guid;
 
     struct capability node_caps[] = {
         { .name = "ml", .version = host->system_info->ml_capable, .enabled = host->system_info->ml_enabled },
@@ -116,7 +124,7 @@ void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_dat
     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, rrdhost_hostname(wc->host), 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), host->machine_guid, wc->host == localhost ? "parent" : "child");
 
     rrd_unlock();
     freez(node_info.claim_id);
@@ -124,9 +132,47 @@ void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_dat
     freez(host_version);
 
     wc->node_collectors_send = now_realtime_sec();
-#else
-    UNUSED(wc);
-#endif
+    freez(node_id);
+
+}
+
 
-    return;
+void aclk_check_node_info_and_collectors(void)
+{
+    RRDHOST *host;
+
+    if (unlikely(!aclk_connected))
+        return;
+
+    size_t pending = 0;
+    dfe_start_reentrant(rrdhost_root_index, host) {
+
+        struct aclk_sync_host_config *wc = host->aclk_sync_host_config;
+        if (unlikely(!wc))
+            continue;
+
+        if (unlikely(rrdhost_flag_check(host, RRDHOST_FLAG_PENDING_CONTEXT_LOAD))) {
+            internal_error(true, "ACLK SYNC: Context still pending for %s", rrdhost_hostname(host));
+            pending++;
+            continue;
+        }
+
+        if (wc->node_info_send_time && wc->node_info_send_time + 30 < now_realtime_sec()) {
+            wc->node_info_send_time = 0;
+            build_node_info(strdupz(wc->node_id));
+            internal_error(true, "ACLK SYNC: Sending node info for %s", rrdhost_hostname(host));
+        }
+
+        if (wc->node_collectors_send && wc->node_collectors_send + 30 < now_realtime_sec()) {
+            build_node_collectors(strdupz(wc->node_id));
+            internal_error(true, "ACLK SYNC: Sending collectors for %s", rrdhost_hostname(host));
+            wc->node_collectors_send = 0;
+        }
+    }
+    dfe_done(host);
+
+    if(pending)
+        info("ACLK: %zu nodes are pending for contexts to load, skipped sending node info for them", pending);
 }
+
+#endif
diff --git a/database/sqlite/sqlite_aclk_node.h b/database/sqlite/sqlite_aclk_node.h
index c2c54f8c7..6afdf8d78 100644
--- a/database/sqlite/sqlite_aclk_node.h
+++ b/database/sqlite/sqlite_aclk_node.h
@@ -3,6 +3,5 @@
 #ifndef NETDATA_SQLITE_ACLK_NODE_H
 #define NETDATA_SQLITE_ACLK_NODE_H
 
-void sql_build_node_info(struct aclk_database_worker_config *wc, struct aclk_database_cmd cmd);
-void sql_build_node_collectors(struct aclk_database_worker_config *wc);
+void aclk_check_node_info_and_collectors(void);
 #endif //NETDATA_SQLITE_ACLK_NODE_H
diff --git a/database/sqlite/sqlite_context.c b/database/sqlite/sqlite_context.c
index 892292cc7..b72726dc2 100644
--- a/database/sqlite/sqlite_context.c
+++ b/database/sqlite/sqlite_context.c
@@ -117,7 +117,6 @@ void sql_close_context_database(void)
     rc = sqlite3_close_v2(db_context_meta);
     if (unlikely(rc != SQLITE_OK))
         error_report("Error %d while closing the context SQLite database, %s", rc, sqlite3_errstr(rc));
-    return;
 }
 
 //
@@ -243,8 +242,6 @@ failed:
     rc = sqlite3_reset(res);
     if (rc != SQLITE_OK)
         error_report("Failed to reset statement that fetches chart label data, rc = %d", rc);
-
-    return;
 }
 
 // CONTEXT LIST
@@ -372,9 +369,9 @@ int ctx_store_context(uuid_t *host_uuid, VERSIONED_CONTEXT_DATA *context_data)
         goto skip_store;
     }
 
-    rc = sqlite3_bind_int(res, 10, (time_t) context_data->deleted);
+    rc = sqlite3_bind_int(res, 10, context_data->deleted);
     if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind last_time_t to store context details");
+        error_report("Failed to bind deleted flag to store context details");
         goto skip_store;
     }
 
@@ -431,11 +428,11 @@ int ctx_delete_context(uuid_t *host_uuid, VERSIONED_CONTEXT_DATA *context_data)
     if (rc_stored != SQLITE_DONE)
         error_report("Failed to delete context %s, rc = %d", context_data->id, rc_stored);
 #ifdef NETDATA_INTERNAL_CHECKS
-     else {
-         char host_uuid_str[UUID_STR_LEN];
-         uuid_unparse_lower(*host_uuid, host_uuid_str);
-         info("%s: Deleted context %s under host %s", __FUNCTION__ , context_data->id, host_uuid_str);
-     }
+    else {
+        char host_uuid_str[UUID_STR_LEN];
+        uuid_unparse_lower(*host_uuid, host_uuid_str);
+        info("%s: Deleted context %s under host %s", __FUNCTION__, context_data->id, host_uuid_str);
+    }
 #endif
 
 skip_delete:
@@ -449,6 +446,10 @@ skip_delete:
 int sql_context_cache_stats(int op)
 {
     int count, dummy;
+
+    if (unlikely(!db_context_meta))
+        return 0;
+
     netdata_thread_disable_cancelability();
     sqlite3_db_status(db_context_meta, op, &count, &dummy, 0);
     netdata_thread_enable_cancelability();
@@ -489,6 +490,8 @@ int ctx_unittest(void)
     uuid_t host_uuid;
     uuid_generate(host_uuid);
 
+    initialize_thread_key_pool();
+
     int rc = sql_init_context_database(1);
 
     if (rc != SQLITE_OK)
@@ -556,6 +559,7 @@ int ctx_unittest(void)
     freez((void *)context_data.title);
     freez((void *)context_data.chart_type);
     freez((void *)context_data.family);
+    freez((void *)context_data.units);
 
     // The list should be empty
     info("List context start after delete");
diff --git a/database/sqlite/sqlite_db_migration.c b/database/sqlite/sqlite_db_migration.c
index 8b1d01594..3132ae2d0 100644
--- a/database/sqlite/sqlite_db_migration.c
+++ b/database/sqlite/sqlite_db_migration.c
@@ -7,7 +7,7 @@ static int return_int_cb(void *data, int argc, char **argv, char **column)
     int *status = data;
     UNUSED(argc);
     UNUSED(column);
-    *status = str2uint32_t(argv[0]);
+    *status = str2uint32_t(argv[0], NULL);
     return 0;
 }
 
@@ -49,7 +49,7 @@ static int column_exists_in_table(const char *table, const char *column)
 }
 
 const char *database_migrate_v1_v2[] = {
-    "ALTER TABLE host ADD hops INTEGER;",
+    "ALTER TABLE host ADD hops INTEGER NOT NULL DEFAULT 0;",
     NULL
 };
 
diff --git a/database/sqlite/sqlite_functions.c b/database/sqlite/sqlite_functions.c
index 1d03cfc2a..2fca2dfc8 100644
--- a/database/sqlite/sqlite_functions.c
+++ b/database/sqlite/sqlite_functions.c
@@ -49,7 +49,6 @@ const char *database_config[] = {
 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 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);",
@@ -117,7 +116,6 @@ int execute_insert(sqlite3_stmt *res)
             break;
         }
     }
-
     return rc;
 }
 
@@ -156,6 +154,12 @@ static void release_statement(void *statement)
         error_report("Failed to finalize statement, rc = %d", rc);
 }
 
+void initialize_thread_key_pool(void)
+{
+    for (int i = 0; i < MAX_PREPARED_STATEMENTS; i++)
+        (void)pthread_key_create(&key_pool[i], release_statement);
+}
+
 int prepare_statement(sqlite3 *database, const char *query, sqlite3_stmt **statement)
 {
     static __thread uint32_t keys_used = 0;
@@ -448,8 +452,7 @@ int sql_init_database(db_check_action_type_t rebuild, int memory)
 
     info("SQLite database initialization completed");
 
-    for (int i = 0; i < MAX_PREPARED_STATEMENTS; i++)
-        (void)pthread_key_create(&key_pool[i], release_statement);
+    initialize_thread_key_pool();
 
     rc = sqlite3_create_function(db_meta, "u2h", 1, SQLITE_ANY | SQLITE_DETERMINISTIC, 0, sqlite_uuid_parse, 0, 0);
     if (unlikely(rc != SQLITE_OK))
@@ -505,14 +508,15 @@ skip:
         error_report("Failed to finalize statement %s, rc = %d", sql, rc);
     return result;
 }
-
-void db_execute(const char *cmd)
+// Return 0 OK
+// Return 1 Failed
+int db_execute(sqlite3 *db, const char *cmd)
 {
     int rc;
     int cnt = 0;
     while (cnt < SQL_MAX_RETRY) {
         char *err_msg;
-        rc = sqlite3_exec_monitored(db_meta, cmd, 0, 0, &err_msg);
+        rc = sqlite3_exec_monitored(db, 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);
@@ -527,6 +531,7 @@ void db_execute(const char *cmd)
 
         ++cnt;
     }
+    return (rc != SQLITE_OK);
 }
 
 static inline void set_host_node_id(RRDHOST *host, uuid_t *node_id)
@@ -540,7 +545,7 @@ static inline void set_host_node_id(RRDHOST *host, uuid_t *node_id)
         return;
     }
 
-    struct aclk_database_worker_config *wc = host->dbsync_worker;
+    struct aclk_sync_host_config *wc = host->aclk_sync_host_config;
 
     if (unlikely(!host->node_id))
         host->node_id = mallocz(sizeof(*host->node_id));
@@ -594,7 +599,7 @@ int update_node_id(uuid_t *host_id, uuid_t *node_id)
     rrd_wrlock();
     host = rrdhost_find_by_guid(host_guid);
     if (likely(host))
-            set_host_node_id(host, node_id);
+        set_host_node_id(host, node_id);
     rrd_unlock();
 
 failed:
@@ -604,48 +609,6 @@ failed:
     return rc - 1;
 }
 
-#define SQL_SELECT_HOSTNAME_BY_NODE_ID  "SELECT h.hostname FROM node_instance ni, " \
-"host h WHERE ni.host_id = h.host_id AND ni.node_id = @node_id;"
-
-char *get_hostname_by_node_id(char *node)
-{
-    sqlite3_stmt *res = NULL;
-    char  *hostname = NULL;
-    int rc;
-
-    if (unlikely(!db_meta)) {
-        if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
-            error_report("Database has not been initialized");
-        return NULL;
-    }
-
-    uuid_t node_id;
-    if (uuid_parse(node, node_id))
-        return NULL;
-
-    rc = sqlite3_prepare_v2(db_meta, SQL_SELECT_HOSTNAME_BY_NODE_ID, -1, &res, 0);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to prepare statement to fetch hostname by node id");
-        return NULL;
-    }
-
-    rc = sqlite3_bind_blob(res, 1, &node_id, sizeof(node_id), SQLITE_STATIC);
-    if (unlikely(rc != SQLITE_OK)) {
-        error_report("Failed to bind host_id parameter to select node instance information");
-        goto failed;
-    }
-
-    rc = sqlite3_step_monitored(res);
-    if (likely(rc == SQLITE_ROW))
-        hostname = strdupz((char *)sqlite3_column_text(res, 0));
-
-failed:
-    if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
-        error_report("Failed to finalize the prepared statement when search for hostname by node id");
-
-    return hostname;
-}
-
 #define SQL_SELECT_HOST_BY_NODE_ID  "select host_id from node_instance where node_id = @node_id;"
 
 int get_host_id(uuid_t *node_id, uuid_t *host_id)
@@ -684,7 +647,7 @@ failed:
     return (rc == SQLITE_ROW) ? 0 : -1;
 }
 
-#define SQL_SELECT_NODE_ID  "select node_id from node_instance where host_id = @host_id and node_id not null;"
+#define SQL_SELECT_NODE_ID  "SELECT node_id FROM node_instance WHERE host_id = @host_id AND node_id IS NOT NULL;"
 
 int get_node_id(uuid_t *host_id, uuid_t *node_id)
 {
@@ -720,8 +683,8 @@ failed:
     return (rc == SQLITE_ROW) ? 0 : -1;
 }
 
-#define SQL_INVALIDATE_NODE_INSTANCES "update node_instance set node_id = NULL where exists " \
-    "(select host_id from node_instance where host_id = @host_id and (@claim_id is null or claim_id <> @claim_id));"
+#define SQL_INVALIDATE_NODE_INSTANCES "UPDATE node_instance SET node_id = NULL WHERE EXISTS " \
+    "(SELECT host_id FROM node_instance WHERE host_id = @host_id AND (@claim_id IS NULL OR claim_id <> @claim_id));"
 
 void invalidate_node_instances(uuid_t *host_id, uuid_t *claim_id)
 {
@@ -765,8 +728,8 @@ failed:
         error_report("Failed to finalize the prepared statement when invalidating node instance information");
 }
 
-#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;"
+#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 AND h.hops >=0;"
 
 struct node_instance_list *get_node_list(void)
 {
@@ -805,13 +768,18 @@ struct node_instance_list *get_node_list(void)
             uuid_copy(node_list[row].node_id, *((uuid_t *)sqlite3_column_blob(res, 0)));
         if (sqlite3_column_bytes(res, 1) == sizeof(uuid_t)) {
             uuid_t *host_id = (uuid_t *)sqlite3_column_blob(res, 1);
-            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);
-            node_list[row].live = host && (host == localhost || host->receiver) ? 1 : 0;
+            if (rrdhost_flag_check(host, RRDHOST_FLAG_PENDING_CONTEXT_LOAD)) {
+                info("ACLK: 'host:%s' skipping get node list because context is initializing", rrdhost_hostname(host));
+                continue;
+            }
+            uuid_copy(node_list[row].host_id, *host_id);
+            node_list[row].queryable = 1;
+            node_list[row].live = (host && (host == localhost || host->receiver
+                                            || !(rrdhost_flag_check(host, RRDHOST_FLAG_ORPHAN)))) ? 1 : 0;
             node_list[row].hops = (host && host->system_info) ? host->system_info->hops :
-                                  uuid_compare(*host_id, localhost->host_uuid) ? 1 : 0;
+                                  uuid_memcmp(host_id, &localhost->host_uuid) ? 1 : 0;
             node_list[row].hostname =
                 sqlite3_column_bytes(res, 2) ? strdupz((char *)sqlite3_column_text(res, 2)) : NULL;
         }
@@ -950,6 +918,10 @@ int bind_text_null(sqlite3_stmt *res, int position, const char *text, bool can_b
 int sql_metadata_cache_stats(int op)
 {
     int count, dummy;
+
+    if (unlikely(!db_meta))
+        return 0;
+
     netdata_thread_disable_cancelability();
     sqlite3_db_status(db_meta, op, &count, &dummy, 0);
     netdata_thread_enable_cancelability();
diff --git a/database/sqlite/sqlite_functions.h b/database/sqlite/sqlite_functions.h
index 40abd010d..ee63a397c 100644
--- a/database/sqlite/sqlite_functions.h
+++ b/database/sqlite/sqlite_functions.h
@@ -55,7 +55,8 @@ int bind_text_null(sqlite3_stmt *res, int position, const char *text, bool can_b
 int prepare_statement(sqlite3 *database, const char *query, sqlite3_stmt **statement);
 int execute_insert(sqlite3_stmt *res);
 int exec_statement_with_uuid(const char *sql, uuid_t *uuid);
-void db_execute(const char *cmd);
+int db_execute(sqlite3 *database, const char *cmd);
+void initialize_thread_key_pool(void);
 
 // Look up functions
 int get_node_id(uuid_t *host_id, uuid_t *node_id);
diff --git a/database/sqlite/sqlite_health.c b/database/sqlite/sqlite_health.c
index 471fa3add..dd08f63ec 100644
--- a/database/sqlite/sqlite_health.c
+++ b/database/sqlite/sqlite_health.c
@@ -12,7 +12,7 @@
 #define SQL_CREATE_HEALTH_LOG_TABLE(guid) "CREATE TABLE IF NOT EXISTS health_log_%s(hostname text, unique_id int, alarm_id int, alarm_event_id int, config_hash_id blob, updated_by_id int, updates_id int, when_key int, duration int, non_clear_duration int, flags int, exec_run_timestamp int, delay_up_to_timestamp int, name text, chart text, family text, exec text, recipient text, source text, units text, info text, exec_code int, new_status real, old_status real, delay int, new_value double, old_value double, last_repeat int, class text, component text, type text, chart_context text);", guid
 int sql_create_health_log_table(RRDHOST *host) {
     int rc;
-    char *err_msg = NULL, command[MAX_HEALTH_SQL_SIZE + 1];
+    char command[MAX_HEALTH_SQL_SIZE + 1];
 
     if (unlikely(!db_meta)) {
         if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
@@ -25,18 +25,17 @@ int sql_create_health_log_table(RRDHOST *host) {
 
     snprintfz(command, MAX_HEALTH_SQL_SIZE, SQL_CREATE_HEALTH_LOG_TABLE(uuid_str));
 
-    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)", rrdhost_hostname(host), rc, err_msg);
-        sqlite3_free(err_msg);
-        return 1;
+    rc = db_execute(db_meta, command);
+    if (unlikely(rc))
+        error_report("HEALTH [%s]: SQLite error during creation of health log table", rrdhost_hostname(host));
+    else {
+        snprintfz(command, MAX_HEALTH_SQL_SIZE, "CREATE INDEX IF NOT EXISTS health_log_index_%s ON health_log_%s (unique_id); ", uuid_str, uuid_str);
+        rc = db_execute(db_meta, command);
+        if (unlikely(unlikely(rc)))
+            error_report("HEALTH [%s]: SQLite error during creation of health log table index", rrdhost_hostname(host));
     }
 
-    snprintfz(command, MAX_HEALTH_SQL_SIZE, "CREATE INDEX IF NOT EXISTS "
-            "health_log_index_%s ON health_log_%s (unique_id); ", uuid_str, uuid_str);
-    db_execute(command);
-
-    return 0;
+    return rc;
 }
 
 /* Health related SQL queries
@@ -104,7 +103,7 @@ void sql_health_alarm_log_update(RRDHOST *host, ALARM_ENTRY *ae) {
         error_report("HEALTH [%s]: Failed to update health log, rc = %d", rrdhost_hostname(host), rc);
     }
 
-    failed:
+failed:
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
         error_report("HEALTH [%s]: Failed to finalize the prepared statement for updating health log.", rrdhost_hostname(host));
 }
@@ -345,7 +344,7 @@ void sql_health_alarm_log_insert(RRDHOST *host, ALARM_ENTRY *ae) {
     ae->flags |= HEALTH_ENTRY_FLAG_SAVED;
     host->health.health_log_entries_written++;
 
-    failed:
+failed:
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
         error_report("HEALTH [%s]: Failed to finalize the prepared statement for inserting to health log.", rrdhost_hostname(host));
 }
@@ -452,7 +451,7 @@ void sql_health_alarm_log_count(RRDHOST *host) {
 #define SQL_INJECT_REMOVED_UPDATE(guid) "update health_log_%s set flags = flags | ?1, updated_by_id = ?2 where unique_id = ?3; ", guid
 void sql_inject_removed_status(char *uuid_str, uint32_t alarm_id, uint32_t alarm_event_id, uint32_t unique_id, uint32_t max_unique_id)
 {
-    int rc = 0;
+    int rc;
     char command[MAX_HEALTH_SQL_SIZE + 1];
 
     if (!alarm_id || !alarm_event_id || !unique_id || !max_unique_id)
@@ -546,7 +545,7 @@ failed:
 #define SQL_SELECT_MAX_UNIQUE_ID(guid) "SELECT MAX(unique_id) from health_log_%s", guid
 uint32_t sql_get_max_unique_id (char *uuid_str)
 {
-    int rc = 0;
+    int rc;
     char command[MAX_HEALTH_SQL_SIZE + 1];
     uint32_t max_unique_id = 0;
 
@@ -573,10 +572,9 @@ uint32_t sql_get_max_unique_id (char *uuid_str)
 #define SQL_SELECT_LAST_STATUSES(guid) "SELECT new_status, unique_id, alarm_id, alarm_event_id from health_log_%s group by alarm_id having max(alarm_event_id)", guid
 void sql_check_removed_alerts_state(char *uuid_str)
 {
-    int rc = 0;
+    int rc;
     char command[MAX_HEALTH_SQL_SIZE + 1];
-    RRDCALC_STATUS status;
-    uint32_t alarm_id = 0, alarm_event_id = 0, unique_id = 0, max_unique_id = 0;
+    uint32_t max_unique_id = 0;
 
     sqlite3_stmt *res = NULL;
 
@@ -588,6 +586,9 @@ void sql_check_removed_alerts_state(char *uuid_str)
     }
 
      while (sqlite3_step_monitored(res) == SQLITE_ROW) {
+         uint32_t alarm_id, alarm_event_id, unique_id;
+         RRDCALC_STATUS status;
+
          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);
@@ -683,8 +684,7 @@ void sql_health_alarm_log_load(RRDHOST *host) {
         }
 
         // Check if we got last_repeat field
-        time_t last_repeat = 0;
-        last_repeat = (time_t)sqlite3_column_int64(res, 27);
+        time_t last_repeat = (time_t)sqlite3_column_int64(res, 27);
 
         rc = dictionary_get(all_rrdcalcs, (char *) sqlite3_column_text(res, 14));
         if(unlikely(rc)) {
@@ -847,196 +847,161 @@ int sql_store_alert_config_hash(uuid_t *hash_id, struct alert_config *cfg)
         }
     }
 
-    param++;
-    rc = sqlite3_bind_blob(res, param, 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++;
-    rc = sqlite3_bind_string_or_null(res, cfg->alarm, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->alarm, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->template_key, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->template_key, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->on, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->on, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->classification, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->classification, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->component, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->component, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->type, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->type, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->os, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->os, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->host, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->host, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->lookup, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->lookup, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->every, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->every, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->units, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->units, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->calc, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->calc, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->families, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->families, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->plugin, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->plugin, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->module, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->module, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->charts, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->charts, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->green, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->green, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->red, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->red, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->warn, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->warn, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->crit, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->crit, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->exec, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->exec, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->to, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->to, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->info, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->info, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->delay, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->delay, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->options, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->options, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->repeat, param);
+    rc = sqlite3_bind_string_or_null(res, cfg->repeat, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_string_or_null(res, cfg->host_labels, param);
+    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_string_or_null(res, cfg->p_db_lookup_dimensions, param);
+        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_string_or_null(res, cfg->p_db_lookup_method, param);
+        rc = sqlite3_bind_string_or_null(res, cfg->p_db_lookup_method, ++param);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
 
-        param++;
-        rc = sqlite3_bind_int(res, 31, cfg->p_db_lookup_options);
+        rc = sqlite3_bind_int(res, ++param, (int) cfg->p_db_lookup_options);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
 
-        param++;
-        rc = sqlite3_bind_int(res, 32, cfg->p_db_lookup_after);
+        rc = sqlite3_bind_int(res, ++param, (int) cfg->p_db_lookup_after);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
 
-        param++;
-        rc = sqlite3_bind_int(res, 33, cfg->p_db_lookup_before);
+        rc = sqlite3_bind_int(res, ++param, (int) cfg->p_db_lookup_before);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
     } else {
-        param++;
-        rc = sqlite3_bind_null(res, 29);
+        rc = sqlite3_bind_null(res, ++param);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
-        param++;
-        rc = sqlite3_bind_null(res, 30);
+
+        rc = sqlite3_bind_null(res, ++param);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
-        param++;
-        rc = sqlite3_bind_null(res, 31);
+
+        rc = sqlite3_bind_null(res, ++param);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
-        param++;
-        rc = sqlite3_bind_null(res, 32);
+
+        rc = sqlite3_bind_null(res, ++param);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
-        param++;
-        rc = sqlite3_bind_null(res, 33);
+
+        rc = sqlite3_bind_null(res, ++param);
         if (unlikely(rc != SQLITE_OK))
             goto bind_fail;
     }
 
-    param++;
-    rc = sqlite3_bind_int(res, 34, cfg->p_update_every);
+    rc = sqlite3_bind_int(res, ++param, cfg->p_update_every);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
@@ -1050,7 +1015,7 @@ int sql_store_alert_config_hash(uuid_t *hash_id, struct alert_config *cfg)
 
     return 0;
 
-    bind_fail:
+bind_fail:
     error_report("Failed to bind parameter %d to store alert hash_id, rc = %d", param, rc);
     rc = sqlite3_reset(res);
     if (unlikely(rc != SQLITE_OK))
diff --git a/database/sqlite/sqlite_metadata.c b/database/sqlite/sqlite_metadata.c
index 35f928ffa..607d789a5 100644
--- a/database/sqlite/sqlite_metadata.c
+++ b/database/sqlite/sqlite_metadata.c
@@ -64,9 +64,11 @@ enum metadata_opcode {
     METADATA_STORE_CLAIM_ID,
     METADATA_ADD_HOST_INFO,
     METADATA_SCAN_HOSTS,
+    METADATA_LOAD_HOST_CONTEXT,
     METADATA_MAINTENANCE,
     METADATA_SYNC_SHUTDOWN,
     METADATA_UNITTEST,
+    METADATA_ML_LOAD_MODELS,
     // leave this last
     // we need it to check for worker utilization
     METADATA_MAX_ENUMERATIONS_DEFINED
@@ -154,19 +156,43 @@ static int chart_label_store_to_sql_callback(const char *name, const char *value
     return 1;
 }
 
-static void check_and_update_chart_labels(RRDSET *st, BUFFER *work_buffer)
+#define SQL_DELETE_CHART_LABEL "DELETE FROM chart_label WHERE chart_id = @chart_id;"
+#define SQL_DELETE_CHART_LABEL_HISTORY "DELETE FROM chart_label WHERE date_created < %ld AND chart_id = @chart_id;"
+
+static void clean_old_chart_labels(RRDSET *st)
+{
+    char sql[512];
+    time_t first_time_s = rrdset_first_entry_s(st);
+
+    if (unlikely(!first_time_s))
+        snprintfz(sql, 511,SQL_DELETE_CHART_LABEL);
+    else
+        snprintfz(sql, 511,SQL_DELETE_CHART_LABEL_HISTORY, first_time_s);
+
+    int rc = exec_statement_with_uuid(sql, &st->chart_uuid);
+    if (unlikely(rc))
+        error_report("METADATA: 'host:%s' Failed to clean old labels for chart %s", rrdhost_hostname(st->rrdhost), rrdset_name(st));
+}
+
+static int check_and_update_chart_labels(RRDSET *st, BUFFER *work_buffer, size_t *query_counter)
 {
     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);
+    if (new_version == old_version)
+        return 0;
+
+    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);
+    int rc = db_execute(db_meta, buffer_tostring(work_buffer));
+    if (likely(!rc)) {
         st->rrdlabels_last_saved_version = new_version;
-        db_execute(buffer_tostring(work_buffer));
+        (*query_counter)++;
     }
+
+    clean_old_chart_labels(st);
+    return rc;
 }
 
 // Migrate all hosts with hops zero to this host_uuid
@@ -177,12 +203,13 @@ void migrate_localhost(uuid_t *host_uuid)
     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);
-
+    if (!rc) {
+        if (unlikely(db_execute(db_meta, DELETE_MISSING_NODE_INSTANCES)))
+            error_report("Failed to remove deleted hosts from node instances");
+    }
 }
 
-static void store_claim_id(uuid_t *host_id, uuid_t *claim_id)
+static int store_claim_id(uuid_t *host_id, uuid_t *claim_id)
 {
     sqlite3_stmt *res = NULL;
     int rc;
@@ -190,18 +217,18 @@ static void store_claim_id(uuid_t *host_id, uuid_t *claim_id)
     if (unlikely(!db_meta)) {
         if (default_rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE)
             error_report("Database has not been initialized");
-        return;
+        return 1;
     }
 
     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;
+        error_report("Failed to prepare statement to store host claim id");
+        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_id parameter to store node instance information");
+        error_report("Failed to bind host_id parameter to store claim id");
         goto failed;
     }
 
@@ -210,17 +237,19 @@ static void store_claim_id(uuid_t *host_id, uuid_t *claim_id)
     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");
+        error_report("Failed to bind claim_id parameter to host claim id");
         goto failed;
     }
 
     rc = execute_insert(res);
     if (unlikely(rc != SQLITE_DONE))
-        error_report("Failed to store node instance information, rc = %d", rc);
+        error_report("Failed to store host claim id rc = %d", rc);
 
 failed:
     if (unlikely(sqlite3_finalize(res) != SQLITE_OK))
-        error_report("Failed to finalize the prepared statement when storing node instance information");
+        error_report("Failed to finalize the prepared statement when storing a host claim id");
+
+    return rc != SQLITE_DONE;
 }
 
 static void delete_dimension_uuid(uuid_t *dimension_uuid)
@@ -252,7 +281,7 @@ skip_execution:
 
 //
 // Store host and host system info information in the database
-static int sql_store_host_info(RRDHOST *host)
+static int store_host_metadata(RRDHOST *host)
 {
     static __thread sqlite3_stmt *res = NULL;
     int rc, param = 0;
@@ -340,7 +369,7 @@ static int sql_store_host_info(RRDHOST *host)
     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);
+    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);
@@ -349,7 +378,7 @@ bind_fail:
     return 1;
 }
 
-static void sql_store_host_system_info_key_value(const char *name, const char *value, void *data)
+static void add_host_sysinfo_key_value(const char *name, const char *value, void *data)
 {
     struct query_build *lb = data;
 
@@ -365,44 +394,43 @@ static void sql_store_host_system_info_key_value(const char *name, const char *v
     lb->count++;
 }
 
-static BUFFER *sql_store_host_system_info(RRDHOST *host)
+static bool build_host_system_info_statements(RRDHOST *host, BUFFER *work_buffer)
 {
     struct rrdhost_system_info *system_info = host->system_info;
 
     if (unlikely(!system_info))
-        return NULL;
-
-    BUFFER *work_buffer = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+        return false;
 
+    buffer_flush(work_buffer);
     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;
+    add_host_sysinfo_key_value("NETDATA_CONTAINER_OS_NAME", system_info->container_os_name, &key_data);
+    add_host_sysinfo_key_value("NETDATA_CONTAINER_OS_ID", system_info->container_os_id, &key_data);
+    add_host_sysinfo_key_value("NETDATA_CONTAINER_OS_ID_LIKE", system_info->container_os_id_like, &key_data);
+    add_host_sysinfo_key_value("NETDATA_CONTAINER_OS_VERSION", system_info->container_os_version, &key_data);
+    add_host_sysinfo_key_value("NETDATA_CONTAINER_OS_VERSION_ID", system_info->container_os_version_id, &key_data);
+    add_host_sysinfo_key_value("NETDATA_CONTAINER_OS_DETECTION", system_info->host_os_detection, &key_data);
+    add_host_sysinfo_key_value("NETDATA_HOST_OS_NAME", system_info->host_os_name, &key_data);
+    add_host_sysinfo_key_value("NETDATA_HOST_OS_ID", system_info->host_os_id, &key_data);
+    add_host_sysinfo_key_value("NETDATA_HOST_OS_ID_LIKE", system_info->host_os_id_like, &key_data);
+    add_host_sysinfo_key_value("NETDATA_HOST_OS_VERSION", system_info->host_os_version, &key_data);
+    add_host_sysinfo_key_value("NETDATA_HOST_OS_VERSION_ID", system_info->host_os_version_id, &key_data);
+    add_host_sysinfo_key_value("NETDATA_HOST_OS_DETECTION", system_info->host_os_detection, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_KERNEL_NAME", system_info->kernel_name, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_CPU_LOGICAL_CPU_COUNT", system_info->host_cores, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_CPU_FREQ", system_info->host_cpu_freq, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_TOTAL_RAM", system_info->host_ram_total, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_TOTAL_DISK_SIZE", system_info->host_disk_space, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_KERNEL_VERSION", system_info->kernel_version, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_ARCHITECTURE", system_info->architecture, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_VIRTUALIZATION", system_info->virtualization, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_VIRT_DETECTION", system_info->virt_detection, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_CONTAINER", system_info->container, &key_data);
+    add_host_sysinfo_key_value("NETDATA_SYSTEM_CONTAINER_DETECTION", system_info->container_detection, &key_data);
+    add_host_sysinfo_key_value("NETDATA_HOST_IS_K8S_NODE", system_info->is_k8s_node, &key_data);
+
+    return true;
 }
 
 
@@ -410,13 +438,10 @@ static BUFFER *sql_store_host_system_info(RRDHOST *host)
  * 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 int store_chart_metadata(RRDSET *st)
 {
     static __thread sqlite3_stmt *res = NULL;
-    int rc, param = 0;
+    int rc, param = 0, store_rc = 0;
 
     if (unlikely(!db_meta)) {
         if (default_rrd_memory_mode != RRD_MEMORY_MODE_DBENGINE)
@@ -433,98 +458,83 @@ static int sql_store_chart(
         }
     }
 
-    param++;
-    rc = sqlite3_bind_blob(res, 1, chart_uuid, sizeof(*chart_uuid), SQLITE_STATIC);
+    rc = sqlite3_bind_blob(res, ++param, &st->chart_uuid, sizeof(st->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);
+    rc = sqlite3_bind_blob(res, ++param, &st->rrdhost->host_uuid, sizeof(st->rrdhost->host_uuid), SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_text(res, 3, type, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, string2str(st->parts.type), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_text(res, 4, id, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, string2str(st->parts.id), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
+    const char *name = string2str(st->parts.name);
     if (name && *name)
-        rc = sqlite3_bind_text(res, 5, name, -1, SQLITE_STATIC);
+        rc = sqlite3_bind_text(res, ++param, name, -1, SQLITE_STATIC);
     else
-        rc = sqlite3_bind_null(res, 5);
+        rc = sqlite3_bind_null(res, ++param);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_text(res, 6, family, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, rrdset_family(st), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_text(res, 7, context, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, rrdset_context(st), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_text(res, 8, title, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, rrdset_title(st), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_text(res, 9, units, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, rrdset_units(st), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_text(res, 10, plugin, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, rrdset_plugin_name(st), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_text(res, 11, module, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, rrdset_module_name(st), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_int(res, 12, (int) priority);
+    rc = sqlite3_bind_int(res, ++param, (int) st->priority);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_int(res, 13, update_every);
+    rc = sqlite3_bind_int(res, ++param, st->update_every);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_int(res, 14, chart_type);
+    rc = sqlite3_bind_int(res, ++param, st->chart_type);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_int(res, 15, memory_mode);
+    rc = sqlite3_bind_int(res, ++param, st->rrd_memory_mode);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    param++;
-    rc = sqlite3_bind_int(res, 16, (int) history_entries);
+    rc = sqlite3_bind_int(res, ++param, (int) st->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);
+    store_rc = execute_insert(res);
+    if (unlikely(store_rc != SQLITE_DONE))
+        error_report("Failed to store chart, rc = %d", store_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;
+    return store_rc != SQLITE_DONE;
 
 bind_fail:
     error_report("Failed to bind parameter %d to store chart, rc = %d", param, rc);
@@ -537,9 +547,7 @@ bind_fail:
 /*
  * 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 int store_dimension_metadata(RRDDIM *rd)
 {
     static __thread sqlite3_stmt *res = NULL;
     int rc, param = 0;
@@ -559,35 +567,35 @@ static int sql_store_dimension(
         }
     }
 
-    rc = sqlite3_bind_blob(res, ++param, dim_uuid, sizeof(*dim_uuid), SQLITE_STATIC);
+    rc = sqlite3_bind_blob(res, ++param, &rd->metric_uuid, sizeof(rd->metric_uuid), SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    rc = sqlite3_bind_blob(res, ++param, chart_uuid, sizeof(*chart_uuid), SQLITE_STATIC);
+    rc = sqlite3_bind_blob(res, ++param, &rd->rrdset->chart_uuid, sizeof(rd->rrdset->chart_uuid), SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    rc = sqlite3_bind_text(res, ++param, id, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, string2str(rd->id), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    rc = sqlite3_bind_text(res, ++param, name, -1, SQLITE_STATIC);
+    rc = sqlite3_bind_text(res, ++param, string2str(rd->name), -1, SQLITE_STATIC);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    rc = sqlite3_bind_int(res, ++param, (int) multiplier);
+    rc = sqlite3_bind_int(res, ++param, (int) rd->multiplier);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    rc = sqlite3_bind_int(res, ++param, (int ) divisor);
+    rc = sqlite3_bind_int(res, ++param, (int ) rd->divisor);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    rc = sqlite3_bind_int(res, ++param, algorithm);
+    rc = sqlite3_bind_int(res, ++param, rd->algorithm);
     if (unlikely(rc != SQLITE_OK))
         goto bind_fail;
 
-    if (hidden)
+    if (rrddim_option_check(rd, RRDDIM_OPTION_HIDDEN))
         rc = sqlite3_bind_text(res, ++param, "hidden", -1, SQLITE_STATIC);
     else
         rc = sqlite3_bind_null(res, ++param);
@@ -700,7 +708,6 @@ static void cleanup_health_log(void)
 //
 // EVENT LOOP STARTS HERE
 //
-static uv_mutex_t metadata_async_lock;
 
 static void metadata_init_cmd_queue(struct metadata_wc *wc)
 {
@@ -856,6 +863,7 @@ static void start_metadata_cleanup(uv_work_t *req)
     struct metadata_wc *wc = req->data;
     check_dimension_metadata(wc);
     cleanup_health_log();
+    (void) sqlite3_wal_checkpoint(db_meta, NULL);
     worker_is_idle();
 }
 
@@ -863,9 +871,125 @@ struct scan_metadata_payload {
     uv_work_t request;
     struct metadata_wc *wc;
     struct completion *completion;
+    BUFFER *work_buffer;
     uint32_t max_count;
 };
 
+struct host_context_load_thread {
+    uv_thread_t thread;
+    RRDHOST *host;
+    bool busy;
+    bool finished;
+};
+
+static void restore_host_context(void *arg)
+{
+    struct host_context_load_thread *hclt = arg;
+    RRDHOST *host = hclt->host;
+
+    usec_t started_ut = now_monotonic_usec(); (void)started_ut;
+    rrdhost_load_rrdcontext_data(host);
+    usec_t ended_ut = now_monotonic_usec(); (void)ended_ut;
+
+    rrdhost_flag_clear(host, RRDHOST_FLAG_PENDING_CONTEXT_LOAD | RRDHOST_FLAG_CONTEXT_LOAD_IN_PROGRESS);
+
+#ifdef ENABLE_ACLK
+    aclk_queue_node_info(host, false);
+#endif
+
+    internal_error(true, "METADATA: 'host:%s' context load in %0.2f ms", rrdhost_hostname(host),
+        (double)(ended_ut - started_ut) / USEC_PER_MS);
+
+    __atomic_store_n(&hclt->finished, true, __ATOMIC_RELEASE);
+}
+
+// Callback after scan of hosts is done
+static void after_start_host_load_context(uv_work_t *req, int status __maybe_unused)
+{
+    struct scan_metadata_payload *data = req->data;
+    freez(data);
+}
+
+#define MAX_FIND_THREAD_RETRIES (10)
+
+static void cleanup_finished_threads(struct host_context_load_thread *hclt, size_t max_thread_slots, bool wait)
+{
+    for (size_t index = 0; index < max_thread_slots; index++) {
+       if (__atomic_load_n(&(hclt[index].finished), __ATOMIC_RELAXED)
+           || (wait && __atomic_load_n(&(hclt[index].busy), __ATOMIC_ACQUIRE))) {
+           int rc = uv_thread_join(&(hclt[index].thread));
+           if (rc)
+                error("Failed to join thread, rc = %d",rc);
+           __atomic_store_n(&(hclt[index].busy), false, __ATOMIC_RELEASE);
+           __atomic_store_n(&(hclt[index].finished), false, __ATOMIC_RELEASE);
+       }
+    }
+}
+
+static size_t find_available_thread_slot(struct host_context_load_thread *hclt, size_t max_thread_slots, size_t *found_index)
+{
+    size_t retries = MAX_FIND_THREAD_RETRIES;
+    while (retries--) {
+       size_t index = 0;
+       while (index < max_thread_slots) {
+           if (false == __atomic_load_n(&(hclt[index].busy), __ATOMIC_ACQUIRE)) {
+                *found_index = index;
+                return true;
+           }
+           index++;
+       }
+       sleep_usec(10 * USEC_PER_MS);
+    }
+    return false;
+}
+
+static void start_all_host_load_context(uv_work_t *req __maybe_unused)
+{
+    register_libuv_worker_jobs();
+
+    struct scan_metadata_payload *data = req->data;
+    UNUSED(data);
+
+    worker_is_busy(UV_EVENT_HOST_CONTEXT_LOAD);
+    usec_t started_ut = now_monotonic_usec(); (void)started_ut;
+
+    RRDHOST *host;
+
+    size_t max_threads = MIN(get_netdata_cpus() / 2, 6);
+    struct host_context_load_thread *hclt = callocz(max_threads, sizeof(*hclt));
+
+    size_t thread_index;
+    dfe_start_reentrant(rrdhost_root_index, host) {
+       if (rrdhost_flag_check(host, RRDHOST_FLAG_CONTEXT_LOAD_IN_PROGRESS) ||
+           !rrdhost_flag_check(host, RRDHOST_FLAG_PENDING_CONTEXT_LOAD))
+           continue;
+
+       rrdhost_flag_set(host, RRDHOST_FLAG_CONTEXT_LOAD_IN_PROGRESS);
+       internal_error(true, "METADATA: 'host:%s' loading context", rrdhost_hostname(host));
+
+       cleanup_finished_threads(hclt, max_threads, false);
+       bool found_slot = find_available_thread_slot(hclt, max_threads, &thread_index);
+
+       if (unlikely(!found_slot)) {
+           struct host_context_load_thread hclt_sync = {.host = host};
+           restore_host_context(&hclt_sync);
+       }
+       else {
+           __atomic_store_n(&hclt[thread_index].busy, true, __ATOMIC_RELAXED);
+           hclt[thread_index].host = host;
+           assert(0 == uv_thread_create(&hclt[thread_index].thread, restore_host_context, &hclt[thread_index]));
+       }
+    }
+    dfe_done(host);
+
+    cleanup_finished_threads(hclt, max_threads, true);
+    freez(hclt);
+    usec_t ended_ut = now_monotonic_usec(); (void)ended_ut;
+    internal_error(true, "METADATA: 'host:ALL' contexts loaded in %0.2f ms", (double)(ended_ut - started_ut) / USEC_PER_MS);
+
+    worker_is_idle();
+}
+
 // Callback after scan of hosts is done
 static void after_metadata_hosts(uv_work_t *req, int status __maybe_unused)
 {
@@ -881,13 +1005,15 @@ static void after_metadata_hosts(uv_work_t *req, int status __maybe_unused)
     freez(data);
 }
 
-static bool metadata_scan_host(RRDHOST *host, uint32_t max_count, size_t *query_counter) {
+static bool metadata_scan_host(RRDHOST *host, uint32_t max_count, bool use_transaction, BUFFER *work_buffer, size_t *query_counter) {
     RRDSET *st;
     int rc;
 
     bool more_to_do = false;
     uint32_t scan_count = 1;
-    BUFFER *work_buffer = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+
+    if (use_transaction)
+        (void)db_execute(db_meta, "BEGIN TRANSACTION;");
 
     rrdset_foreach_reentrant(st, host) {
         if (scan_count == max_count) {
@@ -900,27 +1026,16 @@ static bool metadata_scan_host(RRDHOST *host, uint32_t max_count, size_t *query_
             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);
+            buffer_flush(work_buffer);
+            rc = check_and_update_chart_labels(st, work_buffer, query_counter);
+            if (unlikely(rc))
+                error_report("METADATA: 'host:%s': Failed to update labels for chart %s", rrdhost_hostname(host), rrdset_name(st));
+            else
+                (*query_counter)++;
+
+            rc = store_chart_metadata(st);
             if (unlikely(rc))
-                internal_error(true, "METADATA: Failed to store chart metadata %s", string2str(st->id));
+               error_report("METADATA: 'host:%s': Failed to store metadata for chart %s", rrdhost_hostname(host), rrdset_name(st));
         }
 
         RRDDIM *rd;
@@ -935,116 +1050,145 @@ static bool metadata_scan_host(RRDHOST *host, uint32_t max_count, size_t *query_
                 else
                     rrddim_flag_clear(rd, RRDDIM_FLAG_META_HIDDEN);
 
-                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));
-
+                rc = store_dimension_metadata(rd);
                 if (unlikely(rc))
-                    error_report("METADATA: Failed to store dimension %s", string2str(rd->id));
+                    error_report("METADATA: 'host:%s': Failed to dimension metadata for chart %s. dimension %s",
+                                 rrdhost_hostname(host), rrdset_name(st),
+                                 rrddim_name(rd));
             }
         }
         rrddim_foreach_done(rd);
     }
     rrdset_foreach_done(st);
 
-    buffer_free(work_buffer);
+    if (use_transaction)
+        (void)db_execute(db_meta, "COMMIT TRANSACTION;");
+
     return more_to_do;
 }
 
+static void store_host_and_system_info(RRDHOST *host, BUFFER *work_buffer, size_t *query_counter)
+{
+    bool free_work_buffer = (NULL == work_buffer);
+
+    if (unlikely(free_work_buffer))
+        work_buffer = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+
+    if (build_host_system_info_statements(host, work_buffer)) {
+        int rc = db_execute(db_meta, buffer_tostring(work_buffer));
+        if (unlikely(rc)) {
+            error_report("METADATA: 'host:%s': Failed to store host updated information in the database", rrdhost_hostname(host));
+            rrdhost_flag_set(host, RRDHOST_FLAG_METADATA_INFO | RRDHOST_FLAG_METADATA_UPDATE);
+        }
+        else {
+            if (likely(query_counter))
+                (*query_counter)++;
+        }
+    }
+
+    if (unlikely(store_host_metadata(host))) {
+        error_report("METADATA: 'host:%s': Failed to store host info in the database", rrdhost_hostname(host));
+        rrdhost_flag_set(host, RRDHOST_FLAG_METADATA_INFO | RRDHOST_FLAG_METADATA_UPDATE);
+    }
+    else {
+        if (likely(query_counter))
+            (*query_counter)++;
+    }
+
+    if (unlikely(free_work_buffer))
+        buffer_free(work_buffer);
+}
+
 // Worker thread to scan hosts for pending metadata to store
 static void start_metadata_hosts(uv_work_t *req __maybe_unused)
 {
     register_libuv_worker_jobs();
 
     RRDHOST *host;
+    int transaction_started = 0;
 
     struct scan_metadata_payload *data = req->data;
     struct metadata_wc *wc = data->wc;
 
+    BUFFER *work_buffer = data->work_buffer;
     usec_t all_started_ut = now_monotonic_usec(); (void)all_started_ut;
     internal_error(true, "METADATA: checking all hosts...");
+    usec_t started_ut = now_monotonic_usec(); (void)started_ut;
 
     bool run_again = false;
     worker_is_busy(UV_EVENT_METADATA_STORE);
 
     if (!data->max_count)
-        db_execute("BEGIN TRANSACTION;");
+        transaction_started = !db_execute(db_meta, "BEGIN TRANSACTION;");
+
     dfe_start_reentrant(rrdhost_root_index, host) {
         if (rrdhost_flag_check(host, RRDHOST_FLAG_ARCHIVED) || !rrdhost_flag_check(host, RRDHOST_FLAG_METADATA_UPDATE))
             continue;
 
         size_t query_counter = 0; (void)query_counter;
-        usec_t started_ut = now_monotonic_usec(); (void)started_ut;
 
         rrdhost_flag_clear(host,RRDHOST_FLAG_METADATA_UPDATE);
 
         if (unlikely(rrdhost_flag_check(host, RRDHOST_FLAG_METADATA_LABELS))) {
             rrdhost_flag_clear(host, RRDHOST_FLAG_METADATA_LABELS);
+
             int rc = exec_statement_with_uuid(SQL_DELETE_HOST_LABELS, &host->host_uuid);
-            if (likely(rc == SQLITE_OK)) {
-                BUFFER *work_buffer = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+            if (likely(!rc)) {
+                query_counter++;
+
+                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));
-                buffer_free(work_buffer);
-                query_counter++;
+                rc = db_execute(db_meta, buffer_tostring(work_buffer));
+
+                if (unlikely(rc)) {
+                    error_report("METADATA: 'host:%s': failed to update metadata host labels", rrdhost_hostname(host));
+                    rrdhost_flag_set(host, RRDHOST_FLAG_METADATA_LABELS | RRDHOST_FLAG_METADATA_UPDATE);
+                }
+                else
+                    query_counter++;
+            } else {
+                error_report("METADATA: 'host:%s': failed to delete old host labels", rrdhost_hostname(host));
+                rrdhost_flag_set(host, RRDHOST_FLAG_METADATA_LABELS | RRDHOST_FLAG_METADATA_UPDATE);
             }
         }
 
         if (unlikely(rrdhost_flag_check(host, RRDHOST_FLAG_METADATA_CLAIMID))) {
             rrdhost_flag_clear(host, RRDHOST_FLAG_METADATA_CLAIMID);
             uuid_t uuid;
-
+            int rc;
             if (likely(host->aclk_state.claimed_id && !uuid_parse(host->aclk_state.claimed_id, uuid)))
-                store_claim_id(&host->host_uuid, &uuid);
+                rc = store_claim_id(&host->host_uuid, &uuid);
             else
-                store_claim_id(&host->host_uuid, NULL);
-
-            query_counter++;
-        }
-
-        if (unlikely(rrdhost_flag_check(host, RRDHOST_FLAG_METADATA_INFO))) {
-            rrdhost_flag_clear(host, RRDHOST_FLAG_METADATA_INFO);
-
-            BUFFER *work_buffer = sql_store_host_system_info(host);
-            if(work_buffer) {
-                db_execute(buffer_tostring(work_buffer));
-                buffer_free(work_buffer);
-                query_counter++;
-            }
+                rc = store_claim_id(&host->host_uuid, NULL);
 
-            int rc = sql_store_host_info(host);
             if (unlikely(rc))
-                error_report("METADATA: 'host:%s': failed to store host info", string2str(host->hostname));
+                rrdhost_flag_set(host, RRDHOST_FLAG_METADATA_CLAIMID | RRDHOST_FLAG_METADATA_UPDATE);
             else
                 query_counter++;
         }
+        if (unlikely(rrdhost_flag_check(host, RRDHOST_FLAG_METADATA_INFO))) {
+            rrdhost_flag_clear(host, RRDHOST_FLAG_METADATA_INFO);
+            store_host_and_system_info(host, work_buffer, &query_counter);
+        }
 
-        if (data->max_count)
-            db_execute("BEGIN TRANSACTION;");
-        if (unlikely(metadata_scan_host(host, data->max_count, &query_counter))) {
+        // For clarity
+        bool use_transaction = data->max_count;
+        if (unlikely(metadata_scan_host(host, data->max_count, use_transaction, work_buffer, &query_counter))) {
             run_again = true;
             rrdhost_flag_set(host,RRDHOST_FLAG_METADATA_UPDATE);
             internal_error(true,"METADATA: 'host:%s': scheduling another run, more charts to store", rrdhost_hostname(host));
         }
-        if (data->max_count)
-            db_execute("COMMIT TRANSACTION;");
-
         usec_t ended_ut = now_monotonic_usec(); (void)ended_ut;
         internal_error(true, "METADATA: 'host:%s': saved metadata with %zu SQL statements, in %0.2f ms",
                        rrdhost_hostname(host), query_counter,
                        (double)(ended_ut - started_ut) / USEC_PER_MS);
     }
     dfe_done(host);
-    if (!data->max_count)
-        db_execute("COMMIT TRANSACTION;");
+
+    if (!data->max_count && transaction_started)
+        transaction_started = db_execute(db_meta, "COMMIT TRANSACTION;");
 
     usec_t all_ended_ut = now_monotonic_usec(); (void)all_ended_ut;
     internal_error(true, "METADATA: checking all hosts completed in %0.2f ms",
@@ -1059,7 +1203,6 @@ static void start_metadata_hosts(uv_work_t *req __maybe_unused)
 
 static void metadata_event_loop(void *arg)
 {
-    service_register(SERVICE_THREAD_TYPE_EVENT_LOOP, NULL, NULL, NULL, true);
     worker_register("METASYNC");
     worker_register_job_name(METADATA_DATABASE_NOOP,        "noop");
     worker_register_job_name(METADATA_DATABASE_TIMER,       "timer");
@@ -1067,6 +1210,7 @@ static void metadata_event_loop(void *arg)
     worker_register_job_name(METADATA_STORE_CLAIM_ID,       "add claim id");
     worker_register_job_name(METADATA_ADD_HOST_INFO,        "add host info");
     worker_register_job_name(METADATA_MAINTENANCE,          "maintenance");
+    worker_register_job_name(METADATA_ML_LOAD_MODELS,       "ml load models");
 
     int ret;
     uv_loop_t *loop;
@@ -1076,6 +1220,7 @@ static void metadata_event_loop(void *arg)
     uv_work_t metadata_cleanup_worker;
 
     uv_thread_set_name_np(wc->thread, "METASYNC");
+//    service_register(SERVICE_THREAD_TYPE_EVENT_LOOP, NULL, NULL, NULL, true);
     loop = wc->loop = mallocz(sizeof(uv_loop_t));
     ret = uv_loop_init(loop);
     if (ret) {
@@ -1112,11 +1257,12 @@ static void metadata_event_loop(void *arg)
     int shutdown = 0;
     wc->row_id = 0;
     completion_mark_complete(&wc->init_complete);
+    BUFFER *work_buffer = buffer_create(1024, &netdata_buffers_statistics.buffers_sqlite);
+    struct scan_metadata_payload *data;
 
     while (shutdown == 0 || (wc->flags & METADATA_WORKER_BUSY)) {
         uuid_t  *uuid;
         RRDHOST *host = NULL;
-        int rc;
 
         worker_is_idle();
         uv_run(loop, UV_RUN_DEFAULT);
@@ -1145,6 +1291,11 @@ static void metadata_event_loop(void *arg)
                 case METADATA_DATABASE_TIMER:
                     break;
 
+                case METADATA_ML_LOAD_MODELS: {
+                    RRDDIM *rd = (RRDDIM *) cmd.param[0];
+                    ml_dimension_load_models(rd);
+                    break;
+                }
                 case METADATA_DEL_DIMENSION:
                     uuid = (uuid_t *) cmd.param[0];
                     if (likely(dimension_can_be_deleted(uuid)))
@@ -1158,9 +1309,7 @@ static void metadata_event_loop(void *arg)
                     break;
                 case METADATA_ADD_HOST_INFO:
                     host = (RRDHOST *) cmd.param[0];
-                    rc = sql_store_host_info(host);
-                    if (unlikely(rc))
-                        error_report("Failed to store host info in the database for %s", string2str(host->hostname));
+                    store_host_and_system_info(host, NULL, NULL);
                     break;
                 case METADATA_SCAN_HOSTS:
                     if (unlikely(metadata_flag_check(wc, METADATA_FLAG_SCANNING_HOSTS)))
@@ -1169,10 +1318,11 @@ static void metadata_event_loop(void *arg)
                     if (unittest_running)
                         break;
 
-                    struct scan_metadata_payload *data = mallocz(sizeof(*data));
+                    data = mallocz(sizeof(*data));
                     data->request.data = data;
                     data->wc = wc;
                     data->completion = cmd.completion;  // Completion by the worker
+                    data->work_buffer = work_buffer;
 
                     if (unlikely(cmd.completion)) {
                         data->max_count = 0;            // 0 will process all pending updates
@@ -1192,6 +1342,19 @@ static void metadata_event_loop(void *arg)
                         metadata_flag_clear(wc, METADATA_FLAG_SCANNING_HOSTS);
                     }
                     break;
+                case METADATA_LOAD_HOST_CONTEXT:;
+                    if (unittest_running)
+                        break;
+
+                    data = callocz(1,sizeof(*data));
+                    data->request.data = data;
+                    data->wc = wc;
+                    if (unlikely(
+                            uv_queue_work(loop,&data->request, start_all_host_load_context,
+                                          after_start_host_load_context))) {
+                        freez(data);
+                    }
+                    break;
                 case METADATA_MAINTENANCE:
                     if (unlikely(metadata_flag_check(wc, METADATA_FLAG_CLEANUP)))
                         break;
@@ -1220,21 +1383,14 @@ static void metadata_event_loop(void *arg)
     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);
     int rc;
-
     do {
         rc = uv_loop_close(loop);
     } while (rc != UV_EBUSY);
 
+    buffer_free(work_buffer);
     freez(loop);
     worker_unregister();
 
@@ -1272,6 +1428,9 @@ void metadata_sync_shutdown(void)
 
 void metadata_sync_shutdown_prepare(void)
 {
+    if (unlikely(!metasync_worker.loop))
+        return;
+
     struct metadata_cmd cmd;
     memset(&cmd, 0, sizeof(cmd));
 
@@ -1303,8 +1462,6 @@ 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);
@@ -1364,6 +1521,20 @@ void metaqueue_host_update_info(RRDHOST *host)
     queue_metadata_cmd(METADATA_ADD_HOST_INFO, host, NULL);
 }
 
+void metaqueue_ml_load_models(RRDDIM *rd)
+{
+    if (unlikely(!metasync_worker.loop))
+        return;
+    queue_metadata_cmd(METADATA_ML_LOAD_MODELS, rd, NULL);
+}
+
+void metadata_queue_load_host_context(RRDHOST *host)
+{
+    if (unlikely(!metasync_worker.loop))
+        return;
+    queue_metadata_cmd(METADATA_LOAD_HOST_CONTEXT, host, NULL);
+}
+
 //
 // unitests
 //
@@ -1419,7 +1590,7 @@ static void *metadata_unittest_threads(void)
             unittest_queue_metadata,
             &tu);
     }
-    uv_async_send(&metasync_worker.async);
+    (void) uv_async_send(&metasync_worker.async);
     sleep_usec(seconds_to_run * USEC_PER_SEC);
 
     __atomic_store_n(&tu.join, 1, __ATOMIC_RELAXED);
diff --git a/database/sqlite/sqlite_metadata.h b/database/sqlite/sqlite_metadata.h
index d578b7a8f..6b0676ee7 100644
--- a/database/sqlite/sqlite_metadata.h
+++ b/database/sqlite/sqlite_metadata.h
@@ -14,7 +14,9 @@ void metadata_sync_shutdown_prepare(void);
 void metaqueue_delete_dimension_uuid(uuid_t *uuid);
 void metaqueue_store_claim_id(uuid_t *host_uuid, uuid_t *claim_uuid);
 void metaqueue_host_update_info(RRDHOST *host);
+void metaqueue_ml_load_models(RRDDIM *rd);
 void migrate_localhost(uuid_t *host_uuid);
+void metadata_queue_load_host_context(RRDHOST *host);
 
 // UNIT TEST
 int metadata_unittest(void);