Обсуждение: 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

> 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