=?UTF-8?Q?Gr=c3=a9goire_de_Turckheim?= <gdeturckheim@xxxxxxxxxxxx> writes: > Le 28/10/2019 à 15:22, Tom Lane a écrit : >> We made some performance improvements for NOTIFY just a couple months >> ago, cf commits b10f40bf0, bb5ae8f6c, bca6e6435, 51004c717. It would >> be interesting to know how much those changes helped your use-case. > If my understanding of the problem is correct, there is no performance > issue with the notification itself. > The problem is the following: a system-wide lock is taken pre-commit, so > any other transaction with a NOTIFY will have to wait for other > transactions to complete before it can leave its own pre-commit stage. Right, but all commits are single-threaded at some granularity. The big problem with NOTIFY is that it sits for a long time holding that lock, if you have a lot of notify traffic. The commits I mentioned should improve that. Anyway, as I said, it would be good to find out whether the already finished fixes are enough to solve your problem, before we debate whether more needs to be done. regards, tom lane
