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Re: Possible planner bug/regression introduced in 8.2.5

From: Jakub Ouhrabka <kuba(at)comgate(dot)cz>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: Possible planner bug/regression introduced in 8.2.5
Date: 2007-10-24 13:46:38
Message-ID: 471F4CBE.5060208@comgate.cz (view raw or flat)
Thread:
Lists: pgsql-bugs
Hi Tom,

>> I tried to simplify the query even more and now I have query which on 
>> 8.2.4 is planned instantly and on 8.2.5 takes cca 8 seconds.
> 
> Are you sure you were using the same planner parameters (particularly
> join_collapse_limit and the geqo threshold) in both cases?

thanks for the reply.

Yes, I hope I'm using same parameters. To exhibit the behaviour I set 
geqo to off and join_collapse_limit (and from_collapse_limit) to 1000.

On the test server, I can start postgresql 8.2.4 and 8.2.5 on the same 
datafiles and there is still this big difference in planning time. I 
hope I'm not missing something obvious and not wasting your time...

What can I do to help to debug it?

Thanks,

Kuba


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