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Change default of pg_stat_statements.track_planning to off.

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Since v13 pg_stat_statements is allowed to track the planning time of
statements when track_planning option is enabled. Its default was on.

But this feature could cause more terrible spinlock contentions in
pg_stat_statements. As a result of this, Robins Tharakan reported that
v13 beta1 showed ~45% performance drop at high DB connection counts
(when compared with v12.3) during fully-cached SELECT-only test using
pgbench.

To avoid this performance regression by the default setting,
this commit changes default of pg_stat_statements.track_planning to off.

Back-patch to v13 where pg_stat_statements.track_planning was introduced.

Reported-by: Robins Tharakan
Author: Fujii Masao
Reviewed-by: Julien Rouhaud
Discussion: https://postgr.es/m/2895b53b033c47ccb22972b589050dd9@EX13D05UWC001.ant.amazon.com
This commit is contained in:
Fujii Masao
2020-07-03 11:35:22 +09:00
parent 947456a823
commit d1763ea8c9
4 changed files with 18 additions and 3 deletions
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contrib/pg_stat_statements/sql/pg_stat_statements.sql
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@ -4,6 +4,7 @@ CREATE EXTENSION pg_stat_statements;
-- simple and compound statements
--
SET pg_stat_statements.track_utility = FALSE;
SET pg_stat_statements.track_planning = TRUE;
SELECT pg_stat_statements_reset();
SELECT 1 AS "int";