On 2014-02-18 23:01:08 +0200, Heikki Linnakangas wrote: > On 02/18/2014 10:51 PM, Andres Freund wrote: > >On 2014-02-18 19:12:32 +0200, Heikki Linnakangas wrote: > >>Yeah, I'm pretty sure that's because of the extra checkpoints. If you look > >>at the individual test graphs, there are clear spikes in latency, but the > >>latency is otherwise small. With a higher TPS, you reach checkpoint_segments > >>quicker; I should've eliminated that effect in the tests I ran... > > > >I don't think that'd be a good idea. The number of full page writes so > >greatly influences the WAL charactersistics, that changing checkpoint > >segments would make the tests much harder to compare. > > I was just thinking of bumping up checkpoint_segments so high that there are > no checkpoints during any of the tests.
Hm. I actually think that full page writes are an interesting part of this because they are so significantly differently sized than normal records. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers