Greetings, * Andres Freund (and...@anarazel.de) wrote: > On 2018-07-31 15:11:52 -0400, Bruce Momjian wrote: > > On Tue, Jun 26, 2018 at 04:26:59PM +0900, Kyotaro HORIGUCHI wrote: > > > Hello. This is the reabased version of slot-limit feature. > > > > > > This patch limits maximum WAL segments to be kept by replication > > > slots. Replication slot is useful to avoid desync with replicas > > > after temporary disconnection but it is dangerous when some of > > > replicas are lost. The WAL space can be exhausted and server can > > > PANIC in the worst case. This can prevent the worst case having a > > > benefit from replication slots using a new GUC variable > > > max_slot_wal_keep_size. > > > > Have you considered just using a boolean to control if max_wal_size > > honors WAL preserved by replication slots, rather than creating the new > > GUC max_slot_wal_keep_size? > > That seems like a bad idea. max_wal_size influences checkpoint > scheduling - there's no good reason to conflate that with retention?
I agree that we shouldn't conflate checkpointing and retention. What I wonder about though is what value will wal_keep_segments have once this new GUC exists..? I wonder if we could deprecate it... I wish we had implemented repliation slots from the start with wal_keep_segments capping the max WAL retained but that ship has sailed and changing it now would break existing configurations. Thanks! Stephen
signature.asc
Description: PGP signature
