> 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.
