Horton

Re: Show WAL write and fsync stats in pg_stat_io

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Nazir Bilal Yavuz <byavuz81@gmail.com>, Melanie Plageman <melanieplageman@gmail.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>, "bharath.rupireddyforpostgres@gmail.com" <bharath.rupireddyforpostgres@gmail.com>, Thomas Munro <thomas.munro@gmail.com>
Date: 2025-02-06T07:32:01Z
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

Hi,

On Thu, Feb 06, 2025 at 12:35:28PM +0900, Michael Paquier wrote:
> On Wed, Feb 05, 2025 at 09:52:14PM -0500, Tom Lane wrote:
> > Michael Paquier <michael@paquier.xyz> writes:
> > Yeah, if we want to assume we can see stats counts left over from
> > initdb, we have to put this in a TAP test, though I dunno if that is
> > the most appropriate one.
> 
> A second option I can think of for the reads is a SQL query in
> pg_walinspect.  We are sure that we have a xlogreader context there,
> forcing reads.
> 
> Anyway, I would just stick all that to TAP, like the attached in 027,
> where we would rely on the startup process to read data, and the
> checkpointer to initialize a segment for the primary.  Perhaps not the
> best position, but we already have similar queries in this test, and
> these two are cheap.  Thoughts about the attached?

That sounds ok, but I wonder if that's the best appropriate place. I could
think of the checkpointer test in 029_stats_restart.pl and the startup/standby
one in one related to standby (030_stats_cleanup_replica.pl?). Though that's
probably just a matter of taste.

s/and the primary WAL some writes/and the primary some WAL writes/

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com