On Mon, Nov 29, 2021 at 9:40 AM Bharath Rupireddy <bharath.rupireddyforpostg...@gmail.com> wrote: > > On Mon, Nov 29, 2021 at 1:48 AM SATYANARAYANA NARLAPURAM > <satyanarlapu...@gmail.com> wrote: > > > >> 3) Instead of the subscriber pulling the slot info, why can't the > >> publisher (via the walsender or a new bg worker maybe?) push the > >> latest slot info? I'm not sure we want to add more functionality to > >> the walsender, if yes, isn't it going to be much simpler? > > > > Standby pulling the information or at least making a first attempt to > > connect to the primary is a better design as primary doesn't need to spend > > its cycles repeatedly connecting to an unreachable standby. In fact, > > primary wouldn't even need to know the followers, for example followers / > > log shipping standbys > > My idea was to let the existing walsender from the primary/publisher > to send the slot info (both logical and physical replication slots) to > the standby/subscriber, probably by piggybacking the slot info with > the WAL currently it sends. Having said that, I don't know the > feasibility of it. Anyways, I'm not in favour of having a new bg > worker to just ship the slot info. The standby/subscriber, while > making connection to primary/publisher, can choose to get the > replication slot info.
I think it is possible that the standby is restoring the WAL directly from the archive location and there might not be any wal sender at time. So I think the idea of standby pulling the WAL looks better to me. > As I said upthread, the problem I see with standby/subscriber pulling > the info is that: how frequently the standby/subscriber is going to > sync the slot info from primary/publisher? How can it ensure that the > latest information exists say when the subscriber is down/crashed > before it picks up the latest slot information? Yeah that is a good question that how frequently the subscriber should fetch the slot information, I think that should be configurable values. And the time delay is more, the chances of losing the latest slot is more. -- Regards, Dilip Kumar EnterpriseDB: http://www.enterprisedb.com