Re: Question about memory allocations
Stephen Conley <cheetah@tanabi.org>
From: Steve <cheetah@tanabi.org>
To: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org
Date: 2007-04-13T03:57:24Z
Lists: pgsql-performance
> I didn't notice anyone address this for you yet. There is a tool in > contrib/pg_buffercache whose purpose in life is to show you what the shared > buffer cache has inside it. The documentation in that directory leads > through installing it. The additional variable you'll likely never know is > what additional information is inside the operating system's buffer cache. Okay -- thanks! I'll take a look at this. >> # Leaving this low makes the DB complain, but I'm not sure what's # >> reasonable. >> checkpoint_segments = 128 > > That's a reasonable setting for a large server. The main downside to setting > it that high is longer recovery periods after a crash, but I doubt that's a > problem for you if you're so brazen as to turn off fsync. Hahaha yeah. It's 100% assumed that if something goes bad we're restoring from the previous day's backup. However because the DB is read only for -most- of the day and only read/write at night it's acceptable risk for us anyway. But good to know that's a reasonable value. Steve