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Fix VACUUM's reporting of dead-tuple counts to the stats collector.

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Historically, VACUUM has just reported its new_rel_tuples estimate
(the same thing it puts into pg_class.reltuples) to the stats collector.
That number counts both live and dead-but-not-yet-reclaimable tuples.
This behavior may once have been right, but modern versions of the
pgstats code track live and dead tuple counts separately, so putting
the total into n_live_tuples and zero into n_dead_tuples is surely
pretty bogus.  Fix it to report live and dead tuple counts separately.

This doesn't really do much for situations where updating transactions
commit concurrently with a VACUUM scan (possibly causing double-counting or
omission of the tuples they add or delete); but it's clearly an improvement
over what we were doing before.

Hari Babu, reviewed by Amit Kapila
This commit is contained in:
Tom Lane
2014-01-18 19:24:20 -05:00
parent 76e91b38ba
commit 115f414124
3 changed files with 20 additions and 9 deletions
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5
src/include/pgstat.h
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@ -333,7 +333,8 @@ typedef struct PgStat_MsgVacuum
Oid m_tableoid;
bool m_autovacuum;
TimestampTz m_vacuumtime;
PgStat_Counter m_tuples;
PgStat_Counter m_live_tuples;
PgStat_Counter m_dead_tuples;
} PgStat_MsgVacuum;
@ -775,7 +776,7 @@ extern void pgstat_reset_single_counter(Oid objectid, PgStat_Single_Reset_Type t
extern void pgstat_report_autovac(Oid dboid);
extern void pgstat_report_vacuum(Oid tableoid, bool shared,
PgStat_Counter tuples);
PgStat_Counter livetuples, PgStat_Counter deadtuples);
extern void pgstat_report_analyze(Relation rel,
PgStat_Counter livetuples, PgStat_Counter deadtuples);