Re: [kris@obsecurity.org: Progress on scaling of FreeBSD on 8 CPU systems]

Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)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