Improve the IndexVacuumInfo/IndexBulkDeleteResult API to allow somewhat sane
behavior in cases where we don't know the heap tuple count accurately; in particular partial vacuum, but this also makes the API a bit more useful for ANALYZE. This patch adds "estimated_count" flags to both structs so that an approximate count can be flagged as such, and adjusts the logic so that approximate counts are not used for updating pg_class.reltuples. This fixes my previous complaint that VACUUM was putting ridiculous values into pg_class.reltuples for indexes. The actual impact of that bug is limited, because the planner only pays attention to reltuples for an index if the index is partial; which probably explains why beta testers hadn't noticed a degradation in plan quality from it. But it needs to be fixed. The whole thing is a bit messy and should be redesigned in future, because reltuples now has the potential to drift quite far away from reality when a long period elapses with no non-partial vacuums. But this is as good as it's going to get for 8.4.
This commit is contained in:
Tom Lane
parent
4334695b30
commit
32ea236361
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/gin/ginvacuum.c,v 1.28 2009/03/24 20:17:11 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/gin/ginvacuum.c,v 1.29 2009/06/06 22:13:50 tgl Exp $
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*-------------------------------------------------------------------------
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*/
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@ -741,6 +741,7 @@ ginvacuumcleanup(PG_FUNCTION_ARGS)
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* tell how many distinct heap entries are referenced by a GIN index.
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*/
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stats->num_index_tuples = info->num_heap_tuples;
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stats->estimated_count = info->estimated_count;
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/*
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* If vacuum full, we already have exclusive lock on the index. Otherwise,
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/gist/gistvacuum.c,v 1.43 2009/03/24 20:17:11 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/gist/gistvacuum.c,v 1.44 2009/06/06 22:13:50 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -524,8 +524,8 @@ gistvacuumcleanup(PG_FUNCTION_ARGS)
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{
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stats = (GistBulkDeleteResult *) palloc0(sizeof(GistBulkDeleteResult));
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/* use heap's tuple count */
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Assert(info->num_heap_tuples >= 0);
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stats->std.num_index_tuples = info->num_heap_tuples;
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stats->std.estimated_count = info->estimated_count;
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/*
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* XXX the above is wrong if index is partial. Would it be OK to just
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@ -679,6 +679,7 @@ gistbulkdelete(PG_FUNCTION_ARGS)
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if (stats == NULL)
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stats = (GistBulkDeleteResult *) palloc0(sizeof(GistBulkDeleteResult));
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/* we'll re-count the tuples each time */
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stats->std.estimated_count = false;
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stats->std.num_index_tuples = 0;
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stack = (GistBDItem *) palloc0(sizeof(GistBDItem));
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/hash/hash.c,v 1.110 2009/05/05 19:36:32 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/hash/hash.c,v 1.111 2009/06/06 22:13:50 tgl Exp $
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*
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* NOTES
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* This file contains only the public interface routines.
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@ -610,6 +610,8 @@ loop_top:
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/*
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* Otherwise, our count is untrustworthy since we may have
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* double-scanned tuples in split buckets. Proceed by dead-reckoning.
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* (Note: we still return estimated_count = false, because using this
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* count is better than not updating reltuples at all.)
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*/
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if (metap->hashm_ntuples > tuples_removed)
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metap->hashm_ntuples -= tuples_removed;
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@ -623,6 +625,7 @@ loop_top:
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/* return statistics */
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if (stats == NULL)
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stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
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stats->estimated_count = false;
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stats->num_index_tuples = num_index_tuples;
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stats->tuples_removed += tuples_removed;
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/* hashvacuumcleanup will fill in num_pages */
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@ -12,7 +12,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.169 2009/05/05 19:36:32 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.170 2009/06/06 22:13:51 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -579,10 +579,11 @@ btvacuumcleanup(PG_FUNCTION_ARGS)
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/*
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* During a non-FULL vacuum it's quite possible for us to be fooled by
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* concurrent page splits into double-counting some index tuples, so
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* disbelieve any total that exceeds the underlying heap's count. (We
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* can't check this during btbulkdelete.)
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* disbelieve any total that exceeds the underlying heap's count ...
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* if we know that accurately. Otherwise this might just make matters
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* worse.
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*/
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if (!info->vacuum_full)
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if (!info->vacuum_full && !info->estimated_count)
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{
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if (stats->num_index_tuples > info->num_heap_tuples)
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stats->num_index_tuples = info->num_heap_tuples;
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@ -618,6 +619,7 @@ btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
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* Reset counts that will be incremented during the scan; needed in case
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* of multiple scans during a single VACUUM command
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*/
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stats->estimated_count = false;
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stats->num_index_tuples = 0;
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stats->pages_deleted = 0;
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.316 2009/05/31 20:55:37 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.317 2009/06/06 22:13:51 tgl Exp $
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*
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*
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* INTERFACE ROUTINES
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@ -1938,8 +1938,9 @@ validate_index(Oid heapId, Oid indexId, Snapshot snapshot)
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ivinfo.index = indexRelation;
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ivinfo.vacuum_full = false;
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ivinfo.analyze_only = false;
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ivinfo.estimated_count = true;
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ivinfo.message_level = DEBUG2;
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ivinfo.num_heap_tuples = -1;
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ivinfo.num_heap_tuples = heapRelation->rd_rel->reltuples;
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ivinfo.strategy = NULL;
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state.tuplesort = tuplesort_begin_datum(TIDOID,
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.137 2009/05/19 08:30:00 heikki Exp $
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* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.138 2009/06/06 22:13:51 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -498,8 +498,9 @@ cleanup:
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ivinfo.index = Irel[ind];
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ivinfo.vacuum_full = false;
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ivinfo.analyze_only = true;
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ivinfo.estimated_count = true;
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ivinfo.message_level = elevel;
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ivinfo.num_heap_tuples = -1; /* not known for sure */
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ivinfo.num_heap_tuples = onerel->rd_rel->reltuples;
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ivinfo.strategy = vac_strategy;
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stats = index_vacuum_cleanup(&ivinfo, NULL);
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@ -13,7 +13,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.387 2009/03/31 22:12:48 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.388 2009/06/06 22:13:51 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -3389,6 +3389,7 @@ scan_index(Relation indrel, double num_tuples)
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ivinfo.index = indrel;
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ivinfo.vacuum_full = true;
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ivinfo.analyze_only = false;
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ivinfo.estimated_count = false;
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ivinfo.message_level = elevel;
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ivinfo.num_heap_tuples = num_tuples;
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ivinfo.strategy = vac_strategy;
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@ -3398,10 +3399,14 @@ scan_index(Relation indrel, double num_tuples)
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if (!stats)
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return;
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/* now update statistics in pg_class */
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vac_update_relstats(indrel,
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stats->num_pages, stats->num_index_tuples,
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false, InvalidTransactionId);
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/*
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* Now update statistics in pg_class, but only if the index says the
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* count is accurate.
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*/
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if (!stats->estimated_count)
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vac_update_relstats(indrel,
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stats->num_pages, stats->num_index_tuples,
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false, InvalidTransactionId);
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ereport(elevel,
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(errmsg("index \"%s\" now contains %.0f row versions in %u pages",
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@ -3417,7 +3422,8 @@ scan_index(Relation indrel, double num_tuples)
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* Check for tuple count mismatch. If the index is partial, then it's OK
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* for it to have fewer tuples than the heap; else we got trouble.
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*/
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if (stats->num_index_tuples != num_tuples)
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if (!stats->estimated_count &&
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stats->num_index_tuples != num_tuples)
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{
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if (stats->num_index_tuples > num_tuples ||
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!vac_is_partial_index(indrel))
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@ -3456,6 +3462,7 @@ vacuum_index(VacPageList vacpagelist, Relation indrel,
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ivinfo.index = indrel;
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ivinfo.vacuum_full = true;
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ivinfo.analyze_only = false;
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ivinfo.estimated_count = false;
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ivinfo.message_level = elevel;
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ivinfo.num_heap_tuples = num_tuples + keep_tuples;
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ivinfo.strategy = vac_strategy;
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@ -3469,10 +3476,14 @@ vacuum_index(VacPageList vacpagelist, Relation indrel,
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if (!stats)
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return;
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/* now update statistics in pg_class */
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vac_update_relstats(indrel,
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stats->num_pages, stats->num_index_tuples,
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false, InvalidTransactionId);
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/*
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* Now update statistics in pg_class, but only if the index says the
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* count is accurate.
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*/
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if (!stats->estimated_count)
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vac_update_relstats(indrel,
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stats->num_pages, stats->num_index_tuples,
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false, InvalidTransactionId);
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ereport(elevel,
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(errmsg("index \"%s\" now contains %.0f row versions in %u pages",
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@ -3490,7 +3501,8 @@ vacuum_index(VacPageList vacpagelist, Relation indrel,
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* Check for tuple count mismatch. If the index is partial, then it's OK
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* for it to have fewer tuples than the heap; else we got trouble.
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*/
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if (stats->num_index_tuples != num_tuples + keep_tuples)
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if (!stats->estimated_count &&
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stats->num_index_tuples != num_tuples + keep_tuples)
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{
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if (stats->num_index_tuples > num_tuples + keep_tuples ||
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!vac_is_partial_index(indrel))
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@ -29,7 +29,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.119 2009/03/24 20:17:14 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.120 2009/06/06 22:13:51 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -84,9 +84,11 @@ typedef struct LVRelStats
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{
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/* hasindex = true means two-pass strategy; false means one-pass */
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bool hasindex;
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bool scanned_all; /* have we scanned all pages (this far)? */
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/* Overall statistics about rel */
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BlockNumber rel_pages;
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double rel_tuples;
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double old_rel_tuples; /* previous value of pg_class.reltuples */
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double rel_tuples; /* counts only tuples on scanned pages */
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BlockNumber pages_removed;
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double tuples_deleted;
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BlockNumber nonempty_pages; /* actually, last nonempty page + 1 */
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@ -96,7 +98,6 @@ typedef struct LVRelStats
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int max_dead_tuples; /* # slots allocated in array */
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ItemPointer dead_tuples; /* array of ItemPointerData */
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int num_index_scans;
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bool scanned_all; /* have we scanned all pages (this far)? */
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} LVRelStats;
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@ -174,8 +175,9 @@ lazy_vacuum_rel(Relation onerel, VacuumStmt *vacstmt,
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vacrelstats = (LVRelStats *) palloc0(sizeof(LVRelStats));
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vacrelstats->num_index_scans = 0;
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vacrelstats->scanned_all = true; /* will be cleared if we skip a page */
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vacrelstats->old_rel_tuples = onerel->rd_rel->reltuples;
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vacrelstats->num_index_scans = 0;
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/* Open all indexes of the relation */
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vac_open_indexes(onerel, RowExclusiveLock, &nindexes, &Irel);
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@ -876,9 +878,9 @@ lazy_vacuum_index(Relation indrel,
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ivinfo.index = indrel;
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ivinfo.vacuum_full = false;
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ivinfo.analyze_only = false;
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ivinfo.estimated_count = true;
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ivinfo.message_level = elevel;
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/* We don't yet know rel_tuples, so pass -1 */
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ivinfo.num_heap_tuples = -1;
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ivinfo.num_heap_tuples = vacrelstats->old_rel_tuples;
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ivinfo.strategy = vac_strategy;
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/* Do bulk deletion */
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@ -908,8 +910,10 @@ lazy_cleanup_index(Relation indrel,
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ivinfo.index = indrel;
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ivinfo.vacuum_full = false;
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ivinfo.analyze_only = false;
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ivinfo.estimated_count = !vacrelstats->scanned_all;
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ivinfo.message_level = elevel;
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ivinfo.num_heap_tuples = vacrelstats->rel_tuples;
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/* use rel_tuples only if we scanned all pages, else fall back */
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ivinfo.num_heap_tuples = vacrelstats->scanned_all ? vacrelstats->rel_tuples : vacrelstats->old_rel_tuples;
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ivinfo.strategy = vac_strategy;
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stats = index_vacuum_cleanup(&ivinfo, stats);
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@ -917,10 +921,14 @@ lazy_cleanup_index(Relation indrel,
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if (!stats)
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return;
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/* now update statistics in pg_class */
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vac_update_relstats(indrel,
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stats->num_pages, stats->num_index_tuples,
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false, InvalidTransactionId);
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/*
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* Now update statistics in pg_class, but only if the index says the
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* count is accurate.
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*/
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if (!stats->estimated_count)
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vac_update_relstats(indrel,
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stats->num_pages, stats->num_index_tuples,
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false, InvalidTransactionId);
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ereport(elevel,
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(errmsg("index \"%s\" now contains %.0f row versions in %u pages",
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|
|
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@ -13,7 +13,7 @@
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*
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* Copyright (c) 2001-2009, PostgreSQL Global Development Group
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*
|
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* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.187 2009/01/01 17:23:46 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.188 2009/06/06 22:13:51 tgl Exp $
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* ----------
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*/
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#include "postgres.h"
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@ -3774,6 +3774,13 @@ pgstat_recv_vacuum(PgStat_MsgVacuum *msg, int len)
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{
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if (msg->m_scanned_all)
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tabentry->last_anl_tuples = msg->m_tuples;
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else
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{
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/* last_anl_tuples must never exceed n_live_tuples+n_dead_tuples */
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tabentry->last_anl_tuples = Min(tabentry->last_anl_tuples,
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tabentry->n_live_tuples);
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}
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if (msg->m_autovacuum)
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tabentry->autovac_analyze_timestamp = msg->m_vacuumtime;
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else
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|
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/access/genam.h,v 1.76 2009/03/24 20:17:14 tgl Exp $
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* $PostgreSQL: pgsql/src/include/access/genam.h,v 1.77 2009/06/06 22:13:52 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -34,14 +34,17 @@ typedef struct IndexBuildResult
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/*
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* Struct for input arguments passed to ambulkdelete and amvacuumcleanup
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*
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* Note that num_heap_tuples will not be valid during ambulkdelete,
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* only amvacuumcleanup.
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* num_heap_tuples is accurate only when estimated_count is false;
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* otherwise it's just an estimate (currently, the estimate is the
|
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* prior value of the relation's pg_class.reltuples field). It will
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* always just be an estimate during ambulkdelete.
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*/
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typedef struct IndexVacuumInfo
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{
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Relation index; /* the index being vacuumed */
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bool vacuum_full; /* VACUUM FULL (we have exclusive lock) */
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bool analyze_only; /* ANALYZE (without any actual vacuum) */
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bool estimated_count; /* num_heap_tuples is an estimate */
|
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int message_level; /* ereport level for progress messages */
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double num_heap_tuples; /* tuples remaining in heap */
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BufferAccessStrategy strategy; /* access strategy for reads */
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|
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@ -60,12 +63,15 @@ typedef struct IndexVacuumInfo
|
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*
|
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* Note: pages_removed is the amount by which the index physically shrank,
|
||||
* if any (ie the change in its total size on disk). pages_deleted and
|
||||
* pages_free refer to free space within the index file.
|
||||
* pages_free refer to free space within the index file. Some index AMs
|
||||
* may compute num_index_tuples by reference to num_heap_tuples, in which
|
||||
* case they should copy the estimated_count field from IndexVacuumInfo.
|
||||
*/
|
||||
typedef struct IndexBulkDeleteResult
|
||||
{
|
||||
BlockNumber num_pages; /* pages remaining in index */
|
||||
BlockNumber pages_removed; /* # removed during vacuum operation */
|
||||
bool estimated_count; /* num_index_tuples is an estimate */
|
||||
double num_index_tuples; /* tuples remaining */
|
||||
double tuples_removed; /* # removed during vacuum operation */
|
||||
BlockNumber pages_deleted; /* # unused pages in index */
|
||||
|
|
|
|||
Loading…
Reference in New Issue