Re: Why won't it index scan?

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От Jim C. Nasby
Тема Re: Why won't it index scan?
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Msg-id 20060523233550.GQ64371@pervasive.com
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Ответ на Re: Why won't it index scan?  ("Ed L." <pgsql-general@bluepolka.net>)
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On Tue, May 23, 2006 at 05:00:13PM -0600, Ed L. wrote:
> On Tuesday May 23 2006 4:55 pm, Jim C. Nasby wrote:
> > Well, I did find one reason not to go ape with this: the
> > number of pages analyzed scales with the number of buckets, so
> > doubling the statistics target will roughly double the ANALYZE
> > time for any table over 6000 pages (though the effect isn't
> > linear, see below). There is a small increase in time for a
> > small table, but I doubt it's enough for anyone to care:
>
> Are you accounting for your well-primed OS and DB caches?  I'd
> think a more realistic test would clear those of the target
> table between measurements.

That was after a number of other analyze runs that had already happened,
and the table way larger than my cache, so it's unlikely that caching
played much of an issue.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

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