Re: Performance regressions in PG 9.3 vs PG 9.0 - Mailing list pgsql-performance

From Tom Lane
Subject Re: Performance regressions in PG 9.3 vs PG 9.0
Date
Msg-id 28394.1396992397@sss.pgh.pa.us
Whole thread Raw
In response to Re: Performance regressions in PG 9.3 vs PG 9.0  (uher dslij <codon3@gmail.com>)
Responses Re: Performance regressions in PG 9.3 vs PG 9.0  (uher dslij <codon3@gmail.com>)
Re: Performance regressions in PG 9.3 vs PG 9.0  (uher dslij <codon3@gmail.com>)
List pgsql-performance
uher dslij <codon3@gmail.com> writes:
> The EXPLAINs all pretty much look like my original post.  The planner in
> 9.2 and above is simply not using bitmap heap scans or bitmap index scans?
>  What could be the reason for this?

I don't see any reason to think this is a planner regression.  The
rowcount estimates are pretty far off in both versions; so it's just a
matter of luck that 9.0 is choosing a better join order than 9.3.

I'd try cranking up the statistics targets for the join columns
(particularly domain_id) and see if that leads to better estimates.

            regards, tom lane


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