Good morning,
With our recent upgrade to PG 15, we've put the max_slot_wal_keep_size into place, setting it about 3% lower than the size of the volume dedicated to pg_wal. However last night we had an incident where the volume filled up while we were performing a massive insert from one table into another.
I don't believe the replica was lagging, and we have pgbackrest configured for async archiving, which I assume was fine. It seemed to just be a matter of PG not cleaning up the WAL. Our understanding was that max_slot_wal_keep_size would prevent this but perhaps it only deals with situations where the replication slot lag is a factor?
Don.