Hi, On Tue, Mar 12, 2024 at 05:51:43PM +0530, Amit Kapila wrote: > On Tue, Mar 12, 2024 at 1:24 PM Bertrand Drouvot > <bertranddrouvot...@gmail.com> wrote: > > > > On Fri, Mar 08, 2024 at 10:42:20PM +0530, Bharath Rupireddy 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? Do you still see any problems with it? > > > > Would that make sense to "simply" discard/prevent those kind of > > invalidations > > for "synced" slot on standby? I mean, do they make sense given the fact that > > those slots are not usable until the standby is promoted? > > > > AFAIR, we don't prevent similar invalidations due to > 'max_slot_wal_keep_size' for sync slots,
Right, we'd invalidate them on the standby should the standby sync slot restart_lsn exceeds the limit. > so why to prevent it for > these new parameters? This will unnecessarily create inconsistency in > the invalidation behavior. Yeah, but I think wal removal has a direct impact on the slot usuability which is probably not the case with the new XID and Timeout ones. That's why I thought about handling them differently (but I'm also fine if that's not the case). Regards, -- Bertrand Drouvot PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
