From: Steinar H. Gunderson <sgunderson@bigfoot.com>
To: pgsql-performance@postgresql.org
Subject: Re: why is bitmap index chosen for this query?
Date: Thu, 18 May 2006 18:46:40 +0200
Message-ID: <20060518164640.GA7291@uio.no> (raw)
In-Reply-To: <20060518164123.98856.qmail@web30710.mail.mud.yahoo.com>
References: <20060518155906.GA6909@uio.no>
<20060518164123.98856.qmail@web30710.mail.mud.yahoo.com>
On Thu, May 18, 2006 at 09:41:23AM -0700, Stephen Byers wrote:
> Does the table perchance fit completely into memory, without
> effective_cache_size indicating that?
>
> Don't know the exact way to answer your question, but my initial instinct is "no way."
What about the working set? Have you tried running the queries multiple times
in a row to see if the results change? It might be that your initial bitmap
scan puts all the relevant bits into cache, which will skew the results.
/* Steinar */
--
Homepage: http://www.sesse.net/
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To: pgsql-performance@postgresql.org
Cc: sgunderson@bigfoot.com
Subject: Re: why is bitmap index chosen for this query?
In-Reply-To: <20060518164640.GA7291@uio.no>
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