Horton

Re: Show WAL write and fsync stats in pg_stat_io

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Nazir Bilal Yavuz <byavuz81@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>, "bharath.rupireddyforpostgres@gmail.com" <bharath.rupireddyforpostgres@gmail.com>
Date: 2023-11-21T00:26:00Z
Lists: pgsql-hackers

Commits

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  1. Fix copy-paste error related to the autovacuum launcher in pgstat_io.c

  2. Move SQL tests of pg_stat_io for WAL data to recovery test 029_stats_restart

  3. Add data for WAL in pg_stat_io and backend statistics

  4. Improve comment on top of pgstat_count_io_op_time()

  5. Refactor pgstat_prepare_io_time() with an input argument instead of a GUC

On Mon, Nov 20, 2023 at 05:43:17PM +0300, Nazir Bilal Yavuz wrote:
> Yes, the timings for the writes and the syncs should work. Another
> question I have in mind is the pg_stat_reset_shared() function. When
> we call it with 'io' it will reset pg_stat_wal's timings and when we
> call it with 'wal' it won't reset them, right?

pg_stat_reset_shared() with a target is IMO a very edge case, so I'm
OK with the approach of resetting timings in pg_stat_wal even if 'io'
was implied because pg_stat_wal would feed partially from pg_stat_io.
I'd take that as a side-cost in favor of compatibility while making
the stats gathering cheaper overall.  I'm OK as well if people
counter-argue on this point, though that would mean to keep entirely
separate views with duplicated fields that serve the same purpose,
impacting all deployments because it would make the stats gathering
heavier for all.
--
Michael