Re: Worse perfomance on 8.2.0 than on 7.4.14 - Mailing list pgsql-performance

From Tom Lane
Subject Re: Worse perfomance on 8.2.0 than on 7.4.14
Date
Msg-id 4049.1167585088@sss.pgh.pa.us
Whole thread Raw
In response to Worse perfomance on 8.2.0 than on 7.4.14  (Rolf Østvik <rolfostvik@yahoo.no>)
Responses Re: Worse perfomance on 8.2.0 than on 7.4.14  (Rolf Østvik <rolfostvik@yahoo.no>)
List pgsql-performance
Rolf =?iso-8859-1?q?=D8stvik?= <rolfostvik@yahoo.no> writes:
> I have a simple query which uses 32ms on 7.4.14 and 1015ms on 8.2.0.

There's something awfully strange about that 8.2 plan --- if it knew
that it'd have to scan all of uut_result_subset (which it should have
known, if the stats were up-to-date), why did it use an indexscan
rather than a seqscan?  Are you sure you haven't tweaked any parameters
you didn't tell us about, such as setting enable_seqscan = off?

            regards, tom lane

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