Horton

Re: per backend I/O statistics

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Cc: Nazir Bilal Yavuz <byavuz81@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2025-01-14T04:56:13Z
Lists: pgsql-hackers 
On Fri, Jan 10, 2025 at 01:56:01PM +0000, Bertrand Drouvot wrote:
> So now, I think that it is not a good idea for the per backend stats to 
> behave differently than the other stats kinds. I think we should get rid of
> the "snapshot" for all of them or for none of them. Reading the above comments,
> it looks like it has already been discussed and that the outcome is to keep
> it for all of them.

Thanks a lot for diving into these details!  I did not recall that
there was a strict argument for the current behavior, even if I was
pretty sure that introducing an exception for the backend stats was
not quite right compared to the other stats kinds.  The consistency
line prevails here, then.
--
Michael

Commits

  1. Rework handling of pending data for backend statistics

  2. Rename some pgstats callbacks related to flush of entries

  3. Relax regression test for fsync check of backend-level stats

  4. Add backend-level statistics to pgstats

  5. Extract logic filling pg_stat_get_io()'s tuplestore into its own routine

  6. Tweak some comments related to variable-numbered stats in pgstat.c