Re: Warts with SELECT DISTINCT - Mailing list pgsql-hackers

From Greg Stark
Subject Re: Warts with SELECT DISTINCT
Date
Msg-id 871wv920vm.fsf@stark.xeocode.com
Whole thread Raw
In response to Re: Warts with SELECT DISTINCT  (Bruno Wolff III <bruno@wolff.to>)
Responses Re: Warts with SELECT DISTINCT  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Bruno Wolff III <bruno@wolff.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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