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Re: Fixing row comparison semantics

From: Martijn van Oosterhout <kleptog(at)svana(dot)org>
To: Pavel Stehule <pavel(dot)stehule(at)hotmail(dot)com>
Cc: pgman(at)candle(dot)pha(dot)pa(dot)us, tgl(at)sss(dot)pgh(dot)pa(dot)us, chriskl(at)familyhealth(dot)com(dot)au,pgsql-hackers(at)postgresql(dot)org
Subject: Re: Fixing row comparison semantics
Date: 2005-12-26 12:40:33
Message-ID: 20051226124032.GB12934@svana.org (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, Dec 26, 2005 at 01:29:19PM +0100, Pavel Stehule wrote:
> 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

That's strange. That's not just doing less-than, but also
distinguishing between equal-to and greater-than. So at the very least
you've have to choose an operator like <=>.

Seems to me you should just define your own operator on an array type
and use that. I don't think the above could use an index scan for
speeding it up so there's no point trying to treat it specially.

Have a nice day,
-- 
Martijn van Oosterhout   <kleptog(at)svana(dot)org>   http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.

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