Re: Warts with SELECT DISTINCT

From: Greg Stark <gsstark(at)mit(dot)edu>
To: Bruno Wolff III <bruno(at)wolff(dot)to>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <gsstark(at)mit(dot)edu>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Warts with SELECT DISTINCT
Date: 2006-05-04 16:47:09
Message-ID: 871wv920vm.fsf@stark.xeocode.com
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Bruno Wolff III <bruno(at)wolff(dot)to> writes:

> Thanks for pointing that out. I should have realized that this was the same
> (or at least close to) issue I was thinking would be a problem initially, but
> then I started thinking that '=' promised more than it did and assumed that
> x = y implies foo(x) = foo(y), which as you point out isn't always true.

Hm. This goes back to the earlier conversation about whether = should ever be
true for two objects that aren't, well, equal. I thought there was some
consensus at the time that sorting should impose a superficial ordering on
items that compare equal but aren't in fact the same.

--
greg

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