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Improve the IndexVacuumInfo/IndexBulkDeleteResult API to allow somewhat sane

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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
2009-06-06 22:13:52 +00:00
parent 4334695b30
commit 32ea236361
10 changed files with 81 additions and 39 deletions
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9
src/backend/postmaster/pgstat.c
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@@ -13,7 +13,7 @@
*
* Copyright (c) 2001-2009, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.187 2009/01/01 17:23:46 momjian Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.188 2009/06/06 22:13:51 tgl Exp $
* ----------
*/
#include "postgres.h"
@@ -3774,6 +3774,13 @@ pgstat_recv_vacuum(PgStat_MsgVacuum *msg, int len)
{
if (msg->m_scanned_all)
tabentry->last_anl_tuples = msg->m_tuples;
else
{
/* last_anl_tuples must never exceed n_live_tuples+n_dead_tuples */
tabentry->last_anl_tuples = Min(tabentry->last_anl_tuples,
tabentry->n_live_tuples);
}
if (msg->m_autovacuum)
tabentry->autovac_analyze_timestamp = msg->m_vacuumtime;
else