Re: Show WAL write and fsync stats in pg_stat_io

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(at)paquier(dot)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
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