On Tue, Nov 8, 2022 at 12:08 PM sirisha chamarthi <sirichamarth...@gmail.com> wrote: > > On Fri, Nov 4, 2022 at 11:02 PM Amit Kapila <amit.kapil...@gmail.com> wrote: >> >> On Fri, Nov 4, 2022 at 1:40 PM sirisha chamarthi >> <sirichamarth...@gmail.com> wrote: >> > >> > A replication slot can be lost when a subscriber is not able to catch up >> > with the load on the primary and the WAL to catch up exceeds >> > max_slot_wal_keep_size. When this happens, target has to be reseeded >> > (pg_dump) from the scratch and this can take longer. I am investigating >> > the options to revive a lost slot. >> > >> >> Why in the first place one has to set max_slot_wal_keep_size if they >> care for WAL more than that? > > Disk full is a typical use where we can't wait until the logical slots to > catch up before truncating the log. >
Ideally, in such a case the subscriber should fall back to the physical standby of the publisher but unfortunately, we don't yet have a functionality where subscribers can continue logical replication from physical standby. Do you think if we had such functionality it would serve our purpose? >> If you have a case where you want to >> handle this case for some particular slot (where you are okay with the >> invalidation of other slots exceeding max_slot_wal_keep_size) then the >> other possibility could be to have a similar variable at the slot >> level but not sure if that is a good idea because you haven't >> presented any such case. > > IIUC, ability to fetch WAL from the archive as a fall back mechanism should > automatically take care of all the lost slots. Do you see a need to take care > of a specific slot? > No, I was just trying to see if your use case can be addressed in some other way. BTW, won't copying the WAL again back from archive can lead to a disk full situation. -- With Regards, Amit Kapila.
