On 2013-10-15 19:29:50 +0200, Magnus Hagander wrote: > On Tue, Oct 15, 2013 at 7:26 PM, Andres Freund <and...@2ndquadrant.com> wrote: > > On 2013-10-15 10:19:06 -0700, Josh Berkus wrote: > >> On 10/15/2013 05:52 AM, Magnus Hagander wrote: > >> > But the argument about being friendly for new users should definitely > >> > have us change wal_level and max_wal_senders. > >> > >> +1 for having replication supported out-of-the-box aside from pg_hba.conf. > >> > >> To put it another way: users are more likely to care about replication > >> than they are about IO overhead on a non-replicated server. And for the > >> users who care about IO overhead, they are more likely to much about in > >> pg.conf *anyway* in order to set a slew of performance-tuning settings. > > > > But it will hurt people restoring backups using pg_restore -j. I think > > people might be rather dissapointed if that slows down by a factor of > > three. > > > > I think we really need to get to the point where we increase the wal > > level ondemand... > > Yeha, there are really two things. > > If we can increase wal_level on demand, that would solve one of them. > Turning that into a SIGHUP parameter would be great. I have no idea > how hard it would be. In theory, couldn't we let it be sighup and then > just have do_pg_start_backup() block until all backends have > acknowledged that they are on the new WAL level somehow? (Yes, I > realize this might be a big simplification, but I'm allowed to hope, > no?)
Depends on what you want to support. For basebackups, that should be doable with some pullups. It's unfortunately more complex than that for streaming rep - we really need persistent standby registration there. Otherwise the wal_level will fall back to minimal when the standby disconnects which will obviously break the standby. > The other problem is max_wal_senders. I think that's a much smaller > problem - setting that one to 5 or so by default shouldn't have a big > impact. But without the wal_level changes, it would also be mostly > pointless... Well, you currently cannot even set it when the wal_level isn't set appropriately, but that that should be easy enough to change. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
