Re: Tuning shared_buffers with ipcs ?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Doug Y <dylists(at)ptd(dot)net>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Tuning shared_buffers with ipcs ?
Date: 2004-10-15 17:51:05
Message-ID: 10905.1097862665@sss.pgh.pa.us
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Doug Y <dylists(at)ptd(dot)net> writes:
> I've seen a couple references to using ipcs to help properly size
> shared_buffers.

I have not seen any such claim, and I do not see any way offhand that
ipcs could help.

> I tried all of the dash commands in the ipcs man page, and the only one
> that might give a clue is ipcs -t which shows the time the semaphores
> were last used. If you look at the example I give below, it appears as
> if I'm only using 4 of the 17 semaphores (PG was started on Oct 8).

This might tell you something about how many concurrent backends you've
used, but nothing about how many shared buffers you need.

regards, tom lane

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