Horton

Re: Add wait event for CommitDelay

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Sami Imseih <samimseih@gmail.com>
Cc: Rafia Sabih <rafia.pghackers@gmail.com>, Ants Aasma <ants@cybertec.at>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-12-05T22:19:24Z
Lists: pgsql-hackers

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

On Fri, Dec 05, 2025 at 10:15:19AM -0600, Sami Imseih wrote:
> 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.

I have never used it myself, but I can see why it could be useful for
monitoring here.  No objections to this addition here. 

> 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."

Yes, your description is more useful than what the patch is proposing.
--
Michael