Re: Use of index in 7.0 vs 6.5 - Mailing list pgsql-sql

From Tom Lane
Subject Re: Use of index in 7.0 vs 6.5
Date
Msg-id 22559.959265549@sss.pgh.pa.us
Whole thread Raw
In response to RE: Use of index in 7.0 vs 6.5  ("Hiroshi Inoue" <Inoue@tpf.co.jp>)
List pgsql-sql
"Hiroshi Inoue" <Inoue@tpf.co.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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