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. > > > 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 Regards, Vignesh