From: | Lincoln Yeoh <lylyeoh(at)mecomb(dot)com> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jeff Hoffmann <jeff(at)propertykey(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: rtree indexes aren't being used with 7.0 |
Date: | 2000-05-16 01:09:15 |
Message-ID: | 3.0.5.32.20000516090915.008f5100@pop.mecomb.po.my |
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Thread: | |
Lists: | pgsql-general |
At 11:13 AM 15-05-2000 -0400, Tom Lane wrote:
>Jeff Hoffmann <jeff(at)propertykey(dot)com> writes:
>Actually, the cost estimator for indexscans is deliberately not linear,
>since it's trying to model the effects of hits in a buffer cache ...
>perhaps that's a pointless refinement when we have no accurate idea of
>the size of the kernel's buffer cache, but certainly the real-world
>behavior is not going to be linear.
Just have something like a few linear "curves" and some IF statements?
That's often good enough in real world scenarios- the whole point about
fuzzy logic. Works very well for high speed lifts, and other seemingly
complex control situations.
Cheerio,
Link.
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