On Wed, May 11, 2011 at 1:12 PM, Josh Berkus <j...@agliodbs.com> wrote: > For 9.1, both master and replica in a sync replication relationship are > required to be fsync'ing to disk. I understand why we had to do that > for our first cut at synch rep. Do you think, though, that it might > become possible to replicate without synch-to-disk for 9.2? > > The use case I have is cloud hosting, where I'd rather have two or three > synchronous standbys than synch to disk.
It's already possible to set fsync=off on the standby if you want. If there is an OS-level crash you'll need to rebuild the standby, but in some cases that may be acceptable. And Simon has already written a patch to add a "receive" mode to sync rep, which I expected will get committed to 9.2. In that mode, the standby can acknowledge the WAL records as soon as they are received, and write them to disk just after. I think we do need some benchmarking there, to figure out whether any changes to the timing of replies are needed in that case. But the basic principal seems sound. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
