From: Gary Doades <gpd@gpdnet.co.uk>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: Strange Create Index behaviour
Date: Wed, 15 Feb 2006 21:34:11 +0000
Message-ID: <43F39E53.1020009@gpdnet.co.uk> (raw)
In-Reply-To: <19779.1140038874@sss.pgh.pa.us>
References: <43F38867.6010701@gpdnet.co.uk>
<19510.1140036968@sss.pgh.pa.us>
<19779.1140038874@sss.pgh.pa.us>
Tom Lane wrote:
> I tried forcing PG to use src/port/qsort.c on the Fedora machine,
> and lo and behold:
> new Fedora 4 machine: shortest 434 msec, longest 8530 msec
>
> So it sure looks like this script does expose a problem on BSD-derived
> qsorts. Curiously, the case that's much the worst for me is the third
> in the script, while the shortest time is the first case, which was slow
> for Gary. So I'd venture that the *BSD code has been tweaked somewhere
> along the way, in a manner that moves the problem around without really
> fixing it. (Anyone want to compare the actual FreeBSD source to what
> we have?)
>
If I run the script again, it is not always the first case that is slow,
it varies from run to run, which is why I repeated it quite a few times
for the test.
Interestingly, if I don't delete the table after a run, but just drop
and re-create the index repeatedly it stays a pretty consistent time,
either repeatedly good or repeatedly bad!
Regards,
Gary.
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To: pgsql-performance@postgresql.org
Cc: gpd@gpdnet.co.uk, tgl@sss.pgh.pa.us
Subject: Re: Strange Create Index behaviour
In-Reply-To: <43F39E53.1020009@gpdnet.co.uk>
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