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From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200307222019.h6MKJvP20649@candle.pha.pa.us>
Subject: Re: min() and NaN
In-Reply-To: <15160.1058902399@sss.pgh.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 22 Jul 2003 16:19:57 -0400 (EDT)
Cc: Stephan Szabo <sszabo@megazone.bigpanda.com>,
	Jean-Luc Lachance <jllachan@nsd.ca>,
	"Michael S. Tibbetts" <mtibbetts@head-cfa.cfa.harvard.edu>,
	pgsql-sql@postgresql.org
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Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Well, my 2 cents is that though we consider NULL when ordering via ORDER
> > BY, we ignore it in MAX because it really isn't a value, and NaN seems
> > to be similar to NULL.
> 
> Good idea, but I don't think we can get away with it.  The spec says
> that MAX/MIN have to be consistent with the comparison operators (and
> therefore with ORDER BY):
> 
>             iii) If MAX or MIN is specified, then the result is respec-
>                  tively the maximum or minimum value in TXA. These results
>                  are determined using the comparison rules specified in
>                  Subclause 8.2, "<comparison predicate>".
> 
> NULL can be special, because it acts specially in comparisons anyway.
> But NaN is just a value of the datatype.
> 
> I'd be willing to go against the spec if I thought that having
> ignore-NaNs behavior was sufficiently important, but I don't think it's
> important enough to disregard the spec...

Yep.

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