Re: Optimizer not using index on 120M row table

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: jim(at)nasby(dot)net
Cc: "scott(dot)marlowe" <scott(dot)marlowe(at)ihs(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: Optimizer not using index on 120M row table
Date: 2003-04-30 04:14:34
Message-ID: 19621.1051676074@sss.pgh.pa.us
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"Jim C. Nasby" <jim(at)nasby(dot)net> writes:
> Should effective_cache_size include the size of shared_buffers?

Yes ... although IMHO, if shared_buffers is large enough to materially
affect that number, it's too large ;-)

> FreeBSD doesn't seem to want to use more than about 300M for disk
> caching, so I currently have shared_buffers set to 90000 or about 700M
> (the box has 2G, but pgsql currently has to share with Sybase). Are
> there any issues with setting shared_buffers so high?

Plenty, see many past threads in pgsql-performance and other lists.
There are strong reasons to think that you should let the kernel do the
bulk of the caching work.

regards, tom lane

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