On Wed, 8 Jul 2009, Dan Armbrust wrote:
With checkpoint_segments set to 10, the checkpoints appear to be happening due to checkpoint_timeout - which I've left at the default of 5 minutes.
OK, then that's as far upwards as you probably need to tweak that for your workload, even though most systems tuned for performance need 30+ instead.
If what you're getting nailed with is the pause during the initial checkpoint processing, the only real option you have on the database side is to lower shared_buffers. You might get some improvement playing with operating system tunables too, to make it buffer less data and write more aggressively instead. The idea is that when the checkpoint starts, there should be little else buffered already. On Linux this is best accomplished with tuning dirty_background_ratio downward for example.
There's more on this subject than you probably ever wanted to know at http://www.westnet.com/~gsmith/content/postgresql/chkp-bgw-83.htm if you haven't seen that already.
-- * Greg Smith gsmith@xxxxxxxxxxxxx http://www.gregsmith.com Baltimore, MD -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
