Horton

Re: Add wait event for CommitDelay

Rafia Sabih <rafia.pghackers@gmail.com>

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From: Rafia Sabih <rafia.pghackers@gmail.com>
To: Sami Imseih <samimseih@gmail.com>
Cc: Ants Aasma <ants@cybertec.at>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-12-08T15:20:46Z
Lists: pgsql-hackers

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  1. Add wait event for the group commit delay before WAL flush

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On Fri, 5 Dec 2025 at 17:15, Sami Imseih <samimseih@gmail.com> wrote:

> Hi,
>
> > So, my colleague Ants Aasma found that a wait_event is missing for
> CommitDelay.
> > This just looks like it was missed, please enlighten if it is left out
> intentionally.
>
> I do not know if it was left out intentionally, there are no comments on
> that
> matter.
>
> I am not sure how widely used this GUC is, but from the quick test that I
> did using pgench TPC-B workload with 50 clients, it seems useful
> since a DBA can set commit_delay too high and you will easily observe
> a single backend constantly in this delay which will impact tps.
> It's good to show this clearly as a wait event.
>
> As far as the patch goes, It makes sense to put this under
> "WaitEventTimeout",
> but it should be placed after CHECKPOINT_WRITE_DELAY in
> alphabetical order, and the description could be improved a bit.
> How about? "Waiting for the commit delay before WAL flush."
>
> Thanks for the review of the patch. Please find the attachment for the
updated version.

-- 
Regards,
Rafia Sabih
CYBERTEC PostgreSQL International GmbH