Re: Superfluous merge/sort

From: Anuradha Ratnaweera <ARatnaweera(at)virtusa(dot)com>
To: Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Superfluous merge/sort
Date: 2003-02-26 04:57:28
Message-ID: 20030226045728.GA12881@aratnaweera.virtusa.com
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On Tue, Feb 25, 2003 at 07:56:14AM -0800, Stephan Szabo wrote:
>
> On Tue, 25 Feb 2003, Anuradha Ratnaweera wrote:
>
> > Question in brief: does the planner/optimizer take into account the
> > foreign key constraints?
> >
> > If the answer is "no", please stop reading here.
>
> Not really. However, as a note, from t1,t2 where t1.id=t2.id is not
> necessarily an identity even with the foreign key due to NULLs.

"not null" doesn't make a difference, either :-(

Anuradha

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