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Avoid counting transaction stats for parallel worker cooperating

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transaction.

The transaction that is initiated by the parallel worker to cooperate
with the actual transaction started by the main backend to complete the
query execution should not be counted as a separate transaction.  The
other internal transactions started and committed by the parallel worker
are still counted as separate transactions as we that is what we do in
other places like autovacuum.

This will partially fix the bloat in transaction stats due to additional
transactions performed by parallel workers.  For a complete fix, we need to
decide how we want to show all the transactions that are started internally
for various operations and that is a matter of separate patch.

Reported-by: Haribabu Kommi
Author: Haribabu Kommi
Reviewed-by: Amit Kapila, Jamison Kirk and Rahila Syed
Backpatch-through: 9.6
Discussion: https://postgr.es/m/CAJrrPGc9=jKXuScvNyQ+VNhO0FZk7LLAShAJRyZjnedd2D61EQ@mail.gmail.com
This commit is contained in:
Amit Kapila 2019-04-10 08:36:42 +05:30
parent 47b6362b58
commit 036f7d3782
4 changed files with 17 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/backend/access/transam/twophase.c
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@ -1574,7 +1574,7 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
PredicateLockTwoPhaseFinish(xid, isCommit); PredicateLockTwoPhaseFinish(xid, isCommit);
/* Count the prepared xact as committed or aborted */ /* Count the prepared xact as committed or aborted */
AtEOXact_PgStat(isCommit); AtEOXact_PgStat(isCommit, false);
/* /*
* And now we can clean up any files we may have left. * And now we can clean up any files we may have left.

4
src/backend/access/transam/xact.c
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@ -2164,7 +2164,7 @@ CommitTransaction(void)
AtEOXact_Files(true); AtEOXact_Files(true);
AtEOXact_ComboCid(); AtEOXact_ComboCid();
AtEOXact_HashTables(true); AtEOXact_HashTables(true);
AtEOXact_PgStat(true); AtEOXact_PgStat(true, is_parallel_worker);
AtEOXact_Snapshot(true, false); AtEOXact_Snapshot(true, false);
AtEOXact_ApplyLauncher(true); AtEOXact_ApplyLauncher(true);
pgstat_report_xact_timestamp(0); pgstat_report_xact_timestamp(0);
@ -2656,7 +2656,7 @@ AbortTransaction(void)
AtEOXact_Files(false); AtEOXact_Files(false);
AtEOXact_ComboCid(); AtEOXact_ComboCid();
AtEOXact_HashTables(false); AtEOXact_HashTables(false);
AtEOXact_PgStat(false); AtEOXact_PgStat(false, is_parallel_worker);
AtEOXact_ApplyLauncher(false); AtEOXact_ApplyLauncher(false);
pgstat_report_xact_timestamp(0); pgstat_report_xact_timestamp(0);
} }

22
src/backend/postmaster/pgstat.c
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@ -2050,18 +2050,22 @@ pgstat_update_heap_dead_tuples(Relation rel, int delta)
* ---------- * ----------
*/ */
void void
AtEOXact_PgStat(bool isCommit) AtEOXact_PgStat(bool isCommit, bool parallel)
{ {
PgStat_SubXactStatus *xact_state; PgStat_SubXactStatus *xact_state;
/* /* Don't count parallel worker transaction stats */
* Count transaction commit or abort. (We use counters, not just bools, if (!parallel)
* in case the reporting message isn't sent right away.) {
*/ /*
if (isCommit) * Count transaction commit or abort. (We use counters, not just
pgStatXactCommit++; * bools, in case the reporting message isn't sent right away.)
else */
pgStatXactRollback++; if (isCommit)
pgStatXactCommit++;
else
pgStatXactRollback++;
}
/* /*
* Transfer transactional insert/update counts into the base tabstat * Transfer transactional insert/update counts into the base tabstat

2
src/include/pgstat.h
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@ -1324,7 +1324,7 @@ extern void pgstat_init_function_usage(FunctionCallInfoData *fcinfo,
extern void pgstat_end_function_usage(PgStat_FunctionCallUsage *fcu, extern void pgstat_end_function_usage(PgStat_FunctionCallUsage *fcu,
bool finalize); bool finalize);
extern void AtEOXact_PgStat(bool isCommit); extern void AtEOXact_PgStat(bool isCommit, bool parallel);
extern void AtEOSubXact_PgStat(bool isCommit, int nestDepth); extern void AtEOSubXact_PgStat(bool isCommit, int nestDepth);
extern void AtPrepare_PgStat(void); extern void AtPrepare_PgStat(void);