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Re: Posible planner improvement?

From: Richard Huxton <dev(at)archonet(dot)com>
To: Luke Lonergan <LLonergan(at)greenplum(dot)com>
Cc: albert(at)sedifa(dot)com, pgsql-performance(at)postgresql(dot)org
Subject: Re: Posible planner improvement?
Date: 2008-05-21 13:09:49
Message-ID: 48341F1D.3090304@archonet.com (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
Luke Lonergan wrote:
> The problem is that the implied join predicate is not being
> propagated.  This is definitely a planner deficiency.

IIRC only equality conditions are propagated and gt, lt, between aren't. 
  I seem to remember that the argument given was that the cost of 
checking for the ability to propagate was too high for the frequency 
when it ocurred.

Of course, what was true for code and machines of 5 years ago might not 
be so today.

-- 
   Richard Huxton
   Archonet Ltd

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