From: Tom Lane <tgl@sss.pgh.pa.us>
To: Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>
Cc: Arjen van der Meijden <acmmailing@tweakers.net>
Cc: pgsql-performance@postgresql.org
Subject: Re: [kris@obsecurity.org: Progress on scaling of FreeBSD on 8 CPU systems]
Date: Mon, 05 Mar 2007 15:38:51 -0500
Message-ID: <22074.1173127131@sss.pgh.pa.us> (raw)
In-Reply-To: <45EC7AC3.2030408@kaltenbrunner.cc>
References: <20070227182621.GE29041@decibel.org>
<20070302150129.GF4885@alvh.no-ip.org>
<45E84790.6050609@tweakers.net>
<45EBF658.30907@tweakers.net>
<45EC02B4.2070409@kaltenbrunner.cc>
<45EC0443.1070107@tweakers.net>
<45EC7AC3.2030408@kaltenbrunner.cc>
Stefan Kaltenbrunner <stefan@kaltenbrunner.cc> writes:
> Arjen van der Meijden wrote:
>> Stefan Kaltenbrunner wrote:
>>> ouch - do I read that right that even after tom's fixes for the
>>> "regressions" in 8.2.0 we are still 30% slower then the -HEAD checkout
>>> from the middle of the 8.2 development cycle ?
>>
>> Yes, and although I tested about 17 different cvs-checkouts, Tom and I
>> weren't really able to figure out where "it" happened. So its a bit of a
>> mystery why the performance is so much worse.
> double ouch - losing that much in performance without an idea WHY it
> happened is really unfortunate :-(
Keep in mind that Arjen's test exercises some rather narrow scenarios;
IIRC its performance is mostly determined by some complicated
bitmap-indexscan cases. So that "30% slower" bit certainly doesn't
represent an across-the-board figure. As best I can tell, the decisions
the planner happened to be making in late June were peculiarly nicely
suited to his test, but not so much for other cases.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, stefan@kaltenbrunner.cc, acmmailing@tweakers.net
Subject: Re: [kris@obsecurity.org: Progress on scaling of FreeBSD on 8 CPU systems]
In-Reply-To: <22074.1173127131@sss.pgh.pa.us>
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