Add wait event for CommitDelay

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."

--
Sami Imseih
Amazon Web Services (AWS)

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

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

Thanks for the review of the patch. Please find the attachment for the updated version.

Thanks! v2 LGTM

--
Sami Imseih
Amazon Web Services (AWS)

On 08/12/2025 21:16, Sami Imseih wrote:

Thanks for the review of the patch. Please find the attachment for the updated version.

Thanks! v2 LGTM

Committed, thanks!

- Heikki