On Fri, Mar 8, 2024 at 10:42 PM Bharath Rupireddy <bharath.rupireddyforpostg...@gmail.com> wrote: > > On Wed, Mar 6, 2024 at 4:49 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > You might want to consider its interaction with sync slots on standby. > > Say, there is no activity on slots in terms of processing the changes > > for slots. Now, we won't perform sync of such slots on standby showing > > them inactive as per your new criteria where as same slots could still > > be valid on primary as the walsender is still active. This may be more > > of a theoretical point as in running system there will probably be > > some activity but I think this needs some thougths. > > I believe the xmin and catalog_xmin of the sync slots on the standby > keep advancing depending on the slots on the primary, no? If yes, the > XID age based invalidation shouldn't be a problem. > > I believe there are no walsenders started for the sync slots on the > standbys, right? If yes, the inactive timeout based invalidation also > shouldn't be a problem. Because, the inactive timeouts for a slot are > tracked only for walsenders because they are the ones that typically > hold replication slots for longer durations and for real replication > use. We did a similar thing in a recent commit [1]. > > Is my understanding right? >
Yes, your understanding is correct. I wanted us to consider having new parameters like 'inactive_replication_slot_timeout' to be at slot-level instead of GUC. I think this new parameter doesn't seem to be the similar as 'max_slot_wal_keep_size' which leads to truncation of WAL at global and then invalidates the appropriate slots. OTOH, the 'inactive_replication_slot_timeout' doesn't appear to have a similar global effect. The other thing we should consider is what if the checkpoint happens at a timeout greater than 'inactive_replication_slot_timeout'? Shall, we consider doing it via some other background process or do we think checkpointer is the best we can have? > Do you still see any problems with it? > Sorry, I haven't done any detailed review yet so can't say with confidence whether there is any problem or not w.r.t sync slots. -- With Regards, Amit Kapila.