Re: Possible planner bug/regression introduced in 8.2.5 - Mailing list pgsql-bugs

From Jakub Ouhrabka
Subject Re: Possible planner bug/regression introduced in 8.2.5
Date
Msg-id 4725FBF4.1080403@comgate.cz
Whole thread Raw
In response to Re: Possible planner bug/regression introduced in 8.2.5  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Possible planner bug/regression introduced in 8.2.5
List pgsql-bugs
Hi Tom,

>> ...probably have some cases like that in your real application.  But I'd
>> expect 8.2.4 to be equally slow because it also contains the code that
>> is slow in that scenario.  I'm hoping to get some time today to think
>> about how that could be fixed.
>
> Please try the attached patch (in addition to the one I sent earlier).

I can confirm that now there is no regression between 8.2.4 and
8.2.5+one-line-patch.

I've also tried your last patch but still for some queries there is long
planning time, e.g. more than 30s on a fast machine for query with 14
regularly JOINed tables plus 8 tables are LEFT OUTER JOINed (all normal
joins are followed by all outer joins). All joins are constrained on
pk/fk. Should this case run faster or is it simply too much for
geqo=off? Shall I prepare a test case?

Thanks,

Kuba

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