To: Gary Doades <gpd@gpdnet.co.uk>
cc: pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org
Subject: Re: qsort again (was Re: [PERFORM] Strange Create Index behaviour) 
In-reply-to: <43F3BF72.6000202@gpdnet.co.uk> 
References: <43F38867.6010701@gpdnet.co.uk> <19510.1140036968@sss.pgh.pa.us>
	<19779.1140038874@sss.pgh.pa.us> <43F39E53.1020009@gpdnet.co.uk>
	<20781.1140046109@sss.pgh.pa.us> <43F3BF72.6000202@gpdnet.co.uk>
Comments: In-reply-to Gary Doades <gpd@gpdnet.co.uk>
	message dated "Wed, 15 Feb 2006 23:55:30 +0000"
Date: Wed, 15 Feb 2006 19:04:46 -0500
Message-ID: <21059.1140048286@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Gary Doades <gpd@gpdnet.co.uk> writes:
> Is this likely to hit me in a random fashion during normal operation, 
> joins, sorts, order by for example?

Yup, anytime you're passing data with that kind of distribution
through a sort.

> So the options are:
> 1) Fix the included qsort.c code and use that
> 2) Get FreeBSD to fix their qsort code
> 3) Both

> I guess that 1 is the real solution in case anyone else's qsort is 
> broken in the same way. Then at least you *could* use it all the time :)

It's reasonable to assume that most of the *BSDen have basically the
same qsort code.  Ours claims to have come from NetBSD sources, but
I don't doubt that they all trace back to a common ancestor.

			regards, tom lane