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Re: Possible planner bug/regression introduced in 8.2.5

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jakub Ouhrabka <kuba(at)comgate(dot)cz>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: Possible planner bug/regression introduced in 8.2.5
Date: 2007-10-29 18:18:15
Message-ID: 13324.1193681895@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-bugs
Jakub Ouhrabka <kuba(at)comgate(dot)cz> writes:
> 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?

By "last patch" you mean
http://archives.postgresql.org/pgsql-committers/2007-10/msg00409.php
?  If so that's about as fast as it's likely to get.  22 tables is well
beyond what I'd consider reasonable to run through the exhaustive
planner.  You should try geqo again.

			regards, tom lane

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