Re: Question about memory allocations

From: Steve <cheetah(at)tanabi(dot)org>
To: Greg Smith <gsmith(at)gregsmith(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Question about memory allocations
Date: 2007-04-13 03:57:24
Message-ID: Pine.GSO.4.64.0704122355360.17955@kittyhawk.tanabi.org
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> 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

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