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Re: Fixing row comparison semantics

From: "Pavel Stehule" <pavel(dot)stehule(at)hotmail(dot)com>
To: pgman(at)candle(dot)pha(dot)pa(dot)us, tgl(at)sss(dot)pgh(dot)pa(dot)us
Cc: chriskl(at)familyhealth(dot)com(dot)au, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Fixing row comparison semantics
Date: 2005-12-26 12:29:19
Message-ID: BAY20-F17C8D0B76C52988BD5636F9340@phx.gbl (view raw or flat)
Thread:
Lists: pgsql-hackers
>
>TODO updated:
>
>	* %Make row-wise comparisons work per SQL spec
>
>	  Right now, '(a, b) < (1, 2)' is processed as 'a < 1 and b < 2', but
>	  the SQL standard requires it to be processed as a column-by-column
>	  comparison, so the proper comparison is '(a < 1) OR (a = 1 AND b < 2)'
>
>

Can we save current behave (with small modification) with other operator, 
like <*

(1,1) <* (1,2) = true
(1,2) <* (2,1) is NULL
(2,3) <* (1,2) = false

it's usefull for multicriterial optimalisation

Regards
Pavel Stehule

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Next:From: Martijn van OosterhoutDate: 2005-12-26 12:40:33
Subject: Re: Fixing row comparison semantics
Previous:From: Martijn van OosterhoutDate: 2005-12-26 12:22:12
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