On Wed, Jul 8, 2009 at 12:50 PM, Tom Lane<tgl@xxxxxxxxxxxxx> wrote: > Dan Armbrust <daniel.armbrust.list@xxxxxxxxx> writes: >> However, once the checkpoint process begins, I get a whole flood of >> queries that take between 1 and 10 seconds to complete. My throughput >> crashes to near nothing. The checkpoint takes between 45 seconds and >> a minute to complete. > > You sure this is 8.3? It should spread out checkpoints over a couple of > minutes by default. [thinks...] Maybe you need to increase > checkpoint_segments some more. If it's forcing the checkpoint in order > to hold down the number of WAL segments used up, that would explain a > fast checkpoint. > > regards, tom lane > Just checked - currently running 8.3.4 on the system I'm testing on. 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. If I double my test load, I end up with checkpoints happening about every 4 minutes, with the log message that I read to indicate that it used up all 10 segments. So not much I can do to keep the checkpoint process from causing a burst of slow queries? Thanks, Dan -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
