On Thu, Aug 25, 2016 at 1:43 PM, Josh Berkus <j...@agliodbs.com> wrote: > On 08/25/2016 01:12 PM, Robert Haas wrote: >>> I agree that #4 is best. I'm not sure it's worth the cost. I'm not worried >>> > at all about the risk of master/slave sync thing, per previous statement. >>> > But if it does have performance implications, per Andres suggestion, then >>> > making it configurable at initdb time probably comes with a cost that's >>> > not >>> > worth paying. >> At this point it's hard to judge, because we don't have any idea what >> the cost might be. I guess if we want to pursue this approach, >> somebody will have to code it up and benchmark it. But what I'm >> inclined to do for starters is put together a patch to go from 16MB -> >> 64MB. Committing that early this cycle will give us time to >> reconsider if that turns out to be painful for reasons we haven't >> thought of yet. And give tool authors time to make adjustments, if >> any are needed. > > The one thing I'd be worried about with the increase in size is folks > using PostgreSQL for very small databases. If your database is only > 30MB or so in size, the increase in size of the WAL will be pretty > significant (+144MB for the base 3 WAL segments). I'm not sure this is > a real problem which users will notice (in today's scales, 144MB ain't > much), but if it turns out to be, it would be nice to have a way to > switch it back *just for them* without recompiling.
I think you may be forgetting that "the base 3 WAL segments" is no longer the default configuration. checkpoint_segments=3 is history; we now have max_wal_size=1GB, which is a maximum of 64 WAL segments, not 3. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers