On 07.06.2007, at 22:42, Greg Smith wrote:
On Thu, 7 Jun 2007, Gunther Mayer wrote:
wal checkpoint config is on pg defaults everywhere, all relevant
config options are commented out. I'm no expert in wal stuff but I
don't see how that could cause the problem?
Checkpoints are very resource intensive and can cause other
processes (including your selects) to hang for a considerable
period of time while they are processing. With the default
parameters, they can happen very frequently. Normally
checkpoint_segments and checkpoint_timeout are increased in order
to keep this from happening.
This would normally be an issue only if you're writing a
substantial amount of data to your tables. If there are a lot of
writes going on, you might get some improvement by adjusting those
parameters upward; the defaults are pretty low. Make sure you read
http://www.postgresql.org/docs/8.2/static/wal-configuration.html
first so you know what you're playing with, there are some recovery
implications invoved.
I remember us having problems with 8.0 background writer, you might
want to try turning it off. Not sure if it behaves as badly in 8.2.
increasing wal buffers might be a good idea also.
Kristo
