On Sat, Sep 26, 2009 at 8:19 AM, Greg Smith <gsm...@gregsmith.com> wrote: > > Another problem spot are checkpoints. If you dirty a very large buffer > cache, that whole thing will have to get dumped to disk eventually, and on > some workloads people have found they have to reduce shared_buffers > specifically to keep this from being too painful.
Hi Greg, Is this the case even if checkpoint_completion_target is set close to 1.0? If you dirty buffers fast enough to dirty most of a huge shared_buffers area between checkpoints, then it seems like lowering the shared_buffers wouldn't reduce the amount of I/O needed, it would just shift the I/O from checkpoints to the backends themselves. It looks like checkpoint_completion_target was introduced in 8.3.0 Cheers, Jeff -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
