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Re: pg_dump and thousands of schemas

From: Robert Klemme <shortcutter(at)googlemail(dot)com>
To: Tatsuo Ishii <ishii(at)postgresql(dot)org>
Cc: pgsql-performance(at)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org
Subject: Re: pg_dump and thousands of schemas
Date: 2012-05-31 14:17:11
Message-ID: CAM9pMnPQb9PUxWAx_VGVCb41ta08rW2AA_G6XXnp+2FcuB1BXQ@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
On Thu, May 31, 2012 at 4:07 PM, Tatsuo Ishii <ishii(at)postgresql(dot)org> wrote:
>> On Thu, May 31, 2012 at 10:45 AM, Tatsuo Ishii <ishii(at)postgresql(dot)org> wrote:
>>> Just for record, I rerun the test again with my single-LOCK patch, and
>>> now total runtime of pg_dump is 113 minutes.
>>> 188 minutes(9.0)->125 minutes(git master)->113 minutes(with my patch).
>>>
>>> So far, I'm glad to see 40% time savings at this point.
>>
>> I see only 9.6% savings (100 * (113/125 - 1)).  What am I missing?
>
> What I meant was (100 * (113/188 - 1)).

OK, my fault was to assume you wanted to measure only your part, while
apparently you meant overall savings.  But Tom had asked for separate
measurements if I understood him correctly.  Also, that measurement of
your change would go after the O(N^2) fix.  It could actually turn out
to be much more than 9% because the overall time would be reduced even
more dramatic.  So it might actually be good for your fix to wait a
bit. ;-)

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

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