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Re: Optimizer Bug?

From: "Mitterwald, Holger" <mittehlg(at)coi(dot)de>
To:
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: Optimizer Bug?
Date: 2000-05-30 12:07:19
Message-ID: 3933AEF7.DE9540F7@coi.de (view raw or flat)
Thread:
Lists: pgsql-bugs
Peter Eisentraut wrote:
[..]
> 
> Sure it's used. Just because it's not mentioned in the select list doesn't
> mean it will be ignored completely. What you get here is a three-way join,
> which is of course slower than a two way join.

What I do not understand at all: The table "preis" is neither used in
the select
nor in the where part of the statement. The result will not change if
the table will
not be here nor will it change if there are other datasets in it. Why
should a DBMS
do a full table scan, do a third join on a table that is not used at
all?

Greetings,
   Holger
P.S.: I tested it on OpenIngres 2.0, and the effects are the same. Funny
thing...

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