Re: per backend WAL statistics

Hi,

On Wed, Mar 05, 2025 at 09:18:16AM -0500, Andres Freund wrote:
> Hi,
>
> On 2025-03-05 13:03:07 +0000, Bertrand Drouvot wrote:
> > But yeah, if 0002 in [1] does not go in, then your concern is valid, so adding
> > the extra check in the attached.
>
> This crashes in cfbot:
>
> https://cirrus-ci.com/task/5111872610893824
>

Thanks for the report! I usually always run a make check-world locally and also
launch the CI tests on my github repo before submitting patches. This time,
that was a one line change (as compared to v13), so confident enough I did not
trigger those tests. Murphy's Law I guess ;-)

So yeah, back to the issue, we have to pay more attention for the WAL stats
because pgWalUsage is "incremented" without any check with pgstat_tracks_backend_bktype()
(that's not the case for the IO stats where the counters are incremented taking
into account pgstat_tracks_backend_bktype()).

So for the moment, in the attached I "just" add a pgstat_tracks_backend_bktype()
check in pgstat_backend_have_pending_cb() but I'm not sure I like it that much...

Will think more about it...

Regards,

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