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Re: Sqlplus tunning

From: Greg Moore <sqlgreg_at_pacbell.net>
Date: Wed, 19 Sep 2001 13:07:44 -0700
Message-ID: <F001.003930DE.20010919131519@fatcity.com>

> As there are no restrictions on the data
> being brought back what is wrong with
> doing a full table scan of each?

True there are no restrictions. The query is not going to return just one row where product number = 443. It's going to cover all of both tables it joins.

A simple unrestricted join of two tables will be faster if you just do a full table scan, you avoid the overhead of also looking at the indexes. But when SUM / GROUP BY are added this general rule doesn't apply and indexes will help significantly.

-- 
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-- 
Author: Greg Moore
  INET: sqlgreg_at_pacbell.net

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Received on Wed Sep 19 2001 - 15:07:44 CDT

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