Re: How would you tune this ?

From: Billy Verreynne <vslabs_at_onwe.co.za>
Date: Thu, 17 Oct 2002 11:22:15 +0200
Message-ID: <aolvhf$qeb$1@ctb-nnrp2.saix.net>

Sebby wrote:

> The schema is analyzed, all usable indexes are used (seen in
> EXPLAIN PLAN), Oracle 8.1.7.1 on Sun Solaris.

How does the explain look?

> What would you recommend ?

Explain plan.

Simply because you have indexes, does not mean that they are used correctly.

Explain plan. See how Oracle does it. Understand Oracle's logic and reasoning behind doing it the way it is. Understand the difference between concepts like a nested loop join, hash join and merge join.

And then try and outsmart the CBO. :-) Or at least give it more information for making the right decision.

The problem with you query does however seem to be the unequal distribution of CentreID's.

--
Billy

Received on Thu Oct 17 2002 - 04:22:15 CDT