Re: 4s query want to run faster

From: Mark Kirkwood <markir(at)paradise(dot)net(dot)nz>
To: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
Cc: Adonias Malosso <malosso(at)gmail(dot)com>, Claus Guttesen <kometen(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: 4s query want to run faster
Date: 2008-02-22 05:10:18
Message-ID: 47BE593A.8000709@paradise.net.nz
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Scott Marlowe wrote:
>
> effective_cache_size is pretty easy to set, and it's not real
> sensitive to small changes, so guesstimation is fine where it's
> concerned. Basically, let your machine run for a while, then add the
> cache and buffer your unix kernel has altogether (top and free will
> tell you these things). If you're running other apps on the server,
> make a SWAG (scientific wild assed guess) how much the other apps are
> pounding on the kernel cache / buffer and set effective_cache_size to
> how much you think postgresql is using of the total and set it to
> that.
>

FWIW - The buffered|cached may well be called something different if you
are not on Linux (I didn't see any platform mentioned - sorry if I
missed it) - e.g for Freebsd it is "Inactive" that shows what the os is
caching and "Cached" actually means something slightly different... (yep
that's caused a lot of confusion in the past...)

Cheers

Mark

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