Re: why is bitmap index chosen for this query?

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От Steinar H. Gunderson
Тема Re: why is bitmap index chosen for this query?
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Msg-id 20060518164640.GA7291@uio.no
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Ответ на Re: why is bitmap index chosen for this query?  (Stephen Byers <stephenabyers@yahoo.com>)
Ответы Re: why is bitmap index chosen for this query?
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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 */
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Homepage: http://www.sesse.net/

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