Hi,
On Tuesday, November 22, 2022 6:15 PM vignesh C <vignes...@gmail.com> wrote: > On Mon, 14 Nov 2022 at 12:14, Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > Hi, > > > > The thread title doesn't really convey the topic under discussion, so > > changed it. IIRC, this has been mentioned by others as well in the > > thread. > > > > On Sat, Nov 12, 2022 at 7:21 PM vignesh C <vignes...@gmail.com> wrote: > > > > > > Few comments: > > > 1) I feel if the user has specified a long delay there is a chance > > > that replication may not continue if the replication slot falls > > > behind the current LSN by more than max_slot_wal_keep_size. I feel > > > we should add this reference in the documentation of min_apply_delay > > > as the replication will not continue in this case. > > > > > > > This makes sense to me. Modified accordingly. The updated patch is in [1]. > > > > > 2) I also noticed that if we have to shut down the publisher server > > > with a long min_apply_delay configuration, the publisher server > > > cannot be stopped as the walsender waits for the data to be > > > replicated. Is this behavior ok for the server to wait in this case? > > > If this behavior is ok, we could add a log message as it is not very > > > evident from the log files why the server could not be shut down. > > > > > > > I think for this case, the behavior should be the same as for physical > > replication. Can you please check what is behavior for the case you > > are worried about in physical replication? Note, we already have a > > similar parameter for recovery_min_apply_delay for physical > > replication. > > In the case of physical replication by setting recovery_min_apply_delay, I > noticed that both primary and standby nodes were getting stopped successfully > immediately after the stop server command. In case of logical replication, > stop > server fails: > pg_ctl -D publisher -l publisher.log stop -c waiting for server to shut > down............................................................... > failed > pg_ctl: server does not shut down > > In case of logical replication, the server does not get stopped because the > walsender process is not able to exit: > ps ux | grep walsender > vignesh 1950789 75.3 0.0 8695216 22284 ? Rs 11:51 1:08 > postgres: walsender vignesh [local] START_REPLICATION Thanks, I could reproduce this and I'll update this point in a subsequent version. [1] - https://www.postgresql.org/message-id/TYCPR01MB8373775ECC6972289AF8CB30ED0F9%40TYCPR01MB8373.jpnprd01.prod.outlook.com Best Regards, Takamichi Osumi