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To: Steve <cheetah@tanabi.org>
cc: pgsql-patches@postgreSQL.org, Alvaro Herrera <alvherre@commandprompt.com>
Subject: Re: [HACKERS] choose_bitmap_and again (was Re: [PERFORM] Strangely
	Variable Query Performance)
In-reply-to: <Pine.GSO.4.64.0704141830490.17955@kittyhawk.tanabi.org> 
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Comments: In-reply-to Steve <cheetah@tanabi.org>
	message dated "Sat, 14 Apr 2007 18:55:45 -0400"
Date: Sun, 15 Apr 2007 01:11:02 -0400
Message-ID: <26103.1176613862@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Steve <cheetah@tanabi.org> writes:
>> Steve, can you try this out on your queries and see if it makes better
>> or worse decisions?  It seems to fix your initial complaint but I do
>> not have a large stock of test cases to try.

>  	Wow, this is a remarkable difference.  Queries that were taking 
> minutes to complete are coming up in seconds.  Good work, I think this'll 
> solve my customer's needs for their demo on the 19th :)

Can you find any cases where it makes a worse choice than before?
Another thing to pay attention to is whether the planning time gets
noticeably worse.  If we can't find any cases where it loses badly
on those measures, I'll feel comfortable in applying it...

			regards, tom lane