At Fri, 19 Jun 2020 09:09:03 +0530, Amit Kapila <amit.kapil...@gmail.com> wrote in > On Fri, Jun 19, 2020 at 8:44 AM Kyotaro Horiguchi > <horikyota....@gmail.com> wrote: > > > > At Fri, 19 Jun 2020 10:39:58 +0900, Michael Paquier <mich...@paquier.xyz> > > wrote in > > > Honestly, I find a bit silly the design to compute and use the same > > > minimum LSN value for all the tuples returned by > > > pg_get_replication_slots, and you can actually get a pretty good > > > > I see it as silly. I think I said upthread that it was the distance > > to the point where the slot loses a segment, and it was rejected but > > just removing it makes us unable to estimate the distance so it is > > there. > > > > IIUC, the value of min_safe_lsn will lesser than restart_lsn, so one > can compute the difference of those to see how much ahead the > replication slot's restart_lsn is from min_safe_lsn but still it is > not clear how user will make any use of it. Can you please explain > how the distance you are talking about is useful to users or anyone?
When max_slot_wal_keep_size is set, the slot may retain up to as many as that amount of old WAL segments then suddenly loses the oldest segments. *I* thought that I would use it in an HA cluster tool to inform users about the remaining time (not literally, of course) a disconnected standy is allowed diconnected. Of course even if some segments have been lost, they could be copied from the primary's archive so that's not critical in theory. -- Kyotaro Horiguchi NTT Open Source Software Center
