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