Our callout use of NOTIFY within a TRIGGER may be tangential to the root cause. What we wanted to call out is that neither the NOTIFY page or the https://www.postgresql.org/docs/16/explicit-locking.html page mention that NOTIFY uses an AccessExclusiveLock.
-- Daniel R. <dani...@neophi.com> [http://danielr.neophi.com/] On Wed, Nov 15, 2023 at 1:05 PM Laurenz Albe <laurenz.a...@cybertec.at> wrote: > On Wed, 2023-11-15 at 17:38 +0000, PG Doc comments form wrote: > > The following documentation comment has been logged on the website: > > > > Page: https://www.postgresql.org/docs/16/sql-notify.html > > Description: > > > > It would be good to add to the notes section that use of NOTIFY > especially > > within a TRIGGER requires an AccessExclusiveLock which may cause > performance > > issues. Old thread for reference: > > https://www.postgresql.org/message-id/3598.1363354686%40sss.pgh.pa.us > > I don't see what this has to do with triggers. Even deferred triggers run > *before* this notify lock is taken. > > The only possibility I see for such a lock to be held for a long time is if > COMMIT spends a long time waiting for a reply from a synchronous standby > server. Is that your problem? > > I don't think that would require special documentation, because if your > synchronous standby does not respond in time, you normally have worse > problems than NOTIFY performance. > > Yours, > Laurenz Albe >
