From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> |
Cc: | "Ryan Bradetich" <ryan_bradetich(at)hp(dot)com>, pgsql-sql(at)postgresql(dot)org |
Subject: | Re: Use of index in 7.0 vs 6.5 |
Date: | 2000-05-25 14:39:09 |
Message-ID: | 22559.959265549@sss.pgh.pa.us |
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Lists: | pgsql-sql |
"Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> writes:
>> One way to put a thumb on the scales is to reduce the value of the SET
>> variable random_page_cost. The default value is 4.0, which seems to
>> correspond more or less to reality, but reducing it to 3 or so would
>> shift the planner pretty nicely in the direction of indexscans.
> Or how about changing current fudge factor ?
> For example,from 0.5 to 0.2 which is the fudge factor of attdisbursion
> calculation.
Yes, that's another way --- and probably more defensible than changing
random_page_cost, now that I think about it. Unfortunately it's a
hardwired constant and so not as easily experimented with :-(.
regards, tom lane
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