Brad Nicholson wrote: > > > > Ah, very good point. ?I have added a C comment to clarify why this is > > > > the current behavior; ?attached and applied. > > > > > > > > -- > > > > ?Bruce Momjian ?<bruce@xxxxxxxxxx> ? ? ? ?http://momjian.us > > > > ?EnterpriseDB ? ? ? ? ? ? ? ? ? ? ? ? ? ? http://enterprisedb.com > > > > > > > > > Though has anybody seen a behaviour where synchronous_commit=off is > > > slower than synchronous_commit=on ? Again there are two cases here > > > one with O_* flag and other with f*sync flags. But I had seen that > > > behavior with PostgreSQL 9.0 beta(2 I think) though havent really > > > investigated it much yet .. (though now I dont remember which > > > wal_sync_method flag) . Just curious if anybody has seen that > > > behavior.. > > > > I have trouble believing how synchronous_commit=off could be slower than > > 'on'. > > > > I wonder if it could be contention on wal buffers? > > Say I've turned synchronous_commit off, I drive enough traffic fill up > my wal_buffers. I assume that we would have to start writing buffers > down to disk before allocating to the new process. Uh, good question. I know this report showed ynchronous_commit=off as faster than 'on': http://archives.postgresql.org/pgsql-performance/2010-06/msg00277.php -- Bruce Momjian <bruce@xxxxxxxxxx> http://momjian.us EnterpriseDB http://enterprisedb.com + None of us is going to be here forever. + -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
