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Re: Fixing row comparison semantics

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Fixing row comparison semantics
Date: 2005-12-24 14:53:05
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Lists: pgsql-hackers
Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> writes:
> Can someone explain to me how:
> (a, b) < (1, 2)
> is different to
> a < 1 and b < 2

Right at the moment our code interprets it that way, but this behavior
is wrong per spec.  It should be an ordered column-by-column comparison,
so that the equivalent simple expression is

	(a < 1) OR (a = 1 AND b < 2)

			regards, tom lane

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