From 5e45211a64149b3c659b90ff2de6fa982a5a93ed Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 4 May 2024 14:17:33 +0200 Subject: Adding upstream version 15.5. Signed-off-by: Daniel Baumann --- contrib/pgstattuple/pgstatapprox.c | 319 +++++++++++++++++++++++++++++++++++++ 1 file changed, 319 insertions(+) create mode 100644 contrib/pgstattuple/pgstatapprox.c (limited to 'contrib/pgstattuple/pgstatapprox.c') diff --git a/contrib/pgstattuple/pgstatapprox.c b/contrib/pgstattuple/pgstatapprox.c new file mode 100644 index 0000000..15ddc32 --- /dev/null +++ b/contrib/pgstattuple/pgstatapprox.c @@ -0,0 +1,319 @@ +/*------------------------------------------------------------------------- + * + * pgstatapprox.c + * Bloat estimation functions + * + * Copyright (c) 2014-2022, PostgreSQL Global Development Group + * + * IDENTIFICATION + * contrib/pgstattuple/pgstatapprox.c + * + *------------------------------------------------------------------------- + */ +#include "postgres.h" + +#include "access/heapam.h" +#include "access/htup_details.h" +#include "access/multixact.h" +#include "access/relation.h" +#include "access/transam.h" +#include "access/visibilitymap.h" +#include "access/xact.h" +#include "catalog/namespace.h" +#include "catalog/pg_am_d.h" +#include "commands/vacuum.h" +#include "funcapi.h" +#include "miscadmin.h" +#include "storage/bufmgr.h" +#include "storage/freespace.h" +#include "storage/lmgr.h" +#include "storage/procarray.h" +#include "utils/builtins.h" + +PG_FUNCTION_INFO_V1(pgstattuple_approx); +PG_FUNCTION_INFO_V1(pgstattuple_approx_v1_5); + +Datum pgstattuple_approx_internal(Oid relid, FunctionCallInfo fcinfo); + +typedef struct output_type +{ + uint64 table_len; + uint64 scanned_percent; + uint64 tuple_count; + uint64 tuple_len; + double tuple_percent; + uint64 dead_tuple_count; + uint64 dead_tuple_len; + double dead_tuple_percent; + uint64 free_space; + double free_percent; +} output_type; + +#define NUM_OUTPUT_COLUMNS 10 + +/* + * This function takes an already open relation and scans its pages, + * skipping those that have the corresponding visibility map bit set. + * For pages we skip, we find the free space from the free space map + * and approximate tuple_len on that basis. For the others, we count + * the exact number of dead tuples etc. + * + * This scan is loosely based on vacuumlazy.c:lazy_scan_heap(), but + * we do not try to avoid skipping single pages. + */ +static void +statapprox_heap(Relation rel, output_type *stat) +{ + BlockNumber scanned, + nblocks, + blkno; + Buffer vmbuffer = InvalidBuffer; + BufferAccessStrategy bstrategy; + TransactionId OldestXmin; + + OldestXmin = GetOldestNonRemovableTransactionId(rel); + bstrategy = GetAccessStrategy(BAS_BULKREAD); + + nblocks = RelationGetNumberOfBlocks(rel); + scanned = 0; + + for (blkno = 0; blkno < nblocks; blkno++) + { + Buffer buf; + Page page; + OffsetNumber offnum, + maxoff; + Size freespace; + + CHECK_FOR_INTERRUPTS(); + + /* + * If the page has only visible tuples, then we can find out the free + * space from the FSM and move on. + */ + if (VM_ALL_VISIBLE(rel, blkno, &vmbuffer)) + { + freespace = GetRecordedFreeSpace(rel, blkno); + stat->tuple_len += BLCKSZ - freespace; + stat->free_space += freespace; + continue; + } + + buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, + RBM_NORMAL, bstrategy); + + LockBuffer(buf, BUFFER_LOCK_SHARE); + + page = BufferGetPage(buf); + + /* + * It's not safe to call PageGetHeapFreeSpace() on new pages, so we + * treat them as being free space for our purposes. + */ + if (!PageIsNew(page)) + stat->free_space += PageGetHeapFreeSpace(page); + else + stat->free_space += BLCKSZ - SizeOfPageHeaderData; + + /* We may count the page as scanned even if it's new/empty */ + scanned++; + + if (PageIsNew(page) || PageIsEmpty(page)) + { + UnlockReleaseBuffer(buf); + continue; + } + + /* + * Look at each tuple on the page and decide whether it's live or + * dead, then count it and its size. Unlike lazy_scan_heap, we can + * afford to ignore problems and special cases. + */ + maxoff = PageGetMaxOffsetNumber(page); + + for (offnum = FirstOffsetNumber; + offnum <= maxoff; + offnum = OffsetNumberNext(offnum)) + { + ItemId itemid; + HeapTupleData tuple; + + itemid = PageGetItemId(page, offnum); + + if (!ItemIdIsUsed(itemid) || ItemIdIsRedirected(itemid) || + ItemIdIsDead(itemid)) + { + continue; + } + + Assert(ItemIdIsNormal(itemid)); + + ItemPointerSet(&(tuple.t_self), blkno, offnum); + + tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid); + tuple.t_len = ItemIdGetLength(itemid); + tuple.t_tableOid = RelationGetRelid(rel); + + /* + * We follow VACUUM's lead in counting INSERT_IN_PROGRESS tuples + * as "dead" while DELETE_IN_PROGRESS tuples are "live". We don't + * bother distinguishing tuples inserted/deleted by our own + * transaction. + */ + switch (HeapTupleSatisfiesVacuum(&tuple, OldestXmin, buf)) + { + case HEAPTUPLE_LIVE: + case HEAPTUPLE_DELETE_IN_PROGRESS: + stat->tuple_len += tuple.t_len; + stat->tuple_count++; + break; + case HEAPTUPLE_DEAD: + case HEAPTUPLE_RECENTLY_DEAD: + case HEAPTUPLE_INSERT_IN_PROGRESS: + stat->dead_tuple_len += tuple.t_len; + stat->dead_tuple_count++; + break; + default: + elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result"); + break; + } + } + + UnlockReleaseBuffer(buf); + } + + stat->table_len = (uint64) nblocks * BLCKSZ; + + /* + * We don't know how many tuples are in the pages we didn't scan, so + * extrapolate the live-tuple count to the whole table in the same way + * that VACUUM does. (Like VACUUM, we're not taking a random sample, so + * just extrapolating linearly seems unsafe.) There should be no dead + * tuples in all-visible pages, so no correction is needed for that, and + * we already accounted for the space in those pages, too. + */ + stat->tuple_count = vac_estimate_reltuples(rel, nblocks, scanned, + stat->tuple_count); + + /* It's not clear if we could get -1 here, but be safe. */ + stat->tuple_count = Max(stat->tuple_count, 0); + + /* + * Calculate percentages if the relation has one or more pages. + */ + if (nblocks != 0) + { + stat->scanned_percent = 100 * scanned / nblocks; + stat->tuple_percent = 100.0 * stat->tuple_len / stat->table_len; + stat->dead_tuple_percent = 100.0 * stat->dead_tuple_len / stat->table_len; + stat->free_percent = 100.0 * stat->free_space / stat->table_len; + } + + if (BufferIsValid(vmbuffer)) + { + ReleaseBuffer(vmbuffer); + vmbuffer = InvalidBuffer; + } +} + +/* + * Returns estimated live/dead tuple statistics for the given relid. + * + * The superuser() check here must be kept as the library might be upgraded + * without the extension being upgraded, meaning that in pre-1.5 installations + * these functions could be called by any user. + */ +Datum +pgstattuple_approx(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + + if (!superuser()) + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), + errmsg("must be superuser to use pgstattuple functions"))); + + PG_RETURN_DATUM(pgstattuple_approx_internal(relid, fcinfo)); +} + +/* + * As of pgstattuple version 1.5, we no longer need to check if the user + * is a superuser because we REVOKE EXECUTE on the SQL function from PUBLIC. + * Users can then grant access to it based on their policies. + * + * Otherwise identical to pgstattuple_approx (above). + */ +Datum +pgstattuple_approx_v1_5(PG_FUNCTION_ARGS) +{ + Oid relid = PG_GETARG_OID(0); + + PG_RETURN_DATUM(pgstattuple_approx_internal(relid, fcinfo)); +} + +Datum +pgstattuple_approx_internal(Oid relid, FunctionCallInfo fcinfo) +{ + Relation rel; + output_type stat = {0}; + TupleDesc tupdesc; + bool nulls[NUM_OUTPUT_COLUMNS]; + Datum values[NUM_OUTPUT_COLUMNS]; + HeapTuple ret; + int i = 0; + + if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) + elog(ERROR, "return type must be a row type"); + + if (tupdesc->natts != NUM_OUTPUT_COLUMNS) + elog(ERROR, "incorrect number of output arguments"); + + rel = relation_open(relid, AccessShareLock); + + /* + * Reject attempts to read non-local temporary relations; we would be + * likely to get wrong data since we have no visibility into the owning + * session's local buffers. + */ + if (RELATION_IS_OTHER_TEMP(rel)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot access temporary tables of other sessions"))); + + /* + * We support only relation kinds with a visibility map and a free space + * map. + */ + if (!(rel->rd_rel->relkind == RELKIND_RELATION || + rel->rd_rel->relkind == RELKIND_MATVIEW || + rel->rd_rel->relkind == RELKIND_TOASTVALUE)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("relation \"%s\" is of wrong relation kind", + RelationGetRelationName(rel)), + errdetail_relkind_not_supported(rel->rd_rel->relkind))); + + if (rel->rd_rel->relam != HEAP_TABLE_AM_OID) + ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("only heap AM is supported"))); + + statapprox_heap(rel, &stat); + + relation_close(rel, AccessShareLock); + + memset(nulls, 0, sizeof(nulls)); + + values[i++] = Int64GetDatum(stat.table_len); + values[i++] = Float8GetDatum(stat.scanned_percent); + values[i++] = Int64GetDatum(stat.tuple_count); + values[i++] = Int64GetDatum(stat.tuple_len); + values[i++] = Float8GetDatum(stat.tuple_percent); + values[i++] = Int64GetDatum(stat.dead_tuple_count); + values[i++] = Int64GetDatum(stat.dead_tuple_len); + values[i++] = Float8GetDatum(stat.dead_tuple_percent); + values[i++] = Int64GetDatum(stat.free_space); + values[i++] = Float8GetDatum(stat.free_percent); + + ret = heap_form_tuple(tupdesc, values, nulls); + return HeapTupleGetDatum(ret); +} -- cgit v1.2.3