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Re: Oracle position on hints 9.2.0.X

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Wed, 12 Mar 2003 06:59:16 -0800
Message-ID: <F001.0056778F.20030312065916@fatcity.com>

Something l would try in that position is

create stored outline on ...

    your select statement in 8.1.6

Then select from user_outline_hints
to find what hints Oracle had generated
in the fast plan. Then write the same
set of hints into the SQL in 9.2 (or even export/import the hints) - sometimes
it helps, sometimes it just satisfies the curiosity.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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After spending 2 days trying hints, init parameters, re-writing the query, a completely useless TAR, etc.
to get a query that runs in < 1 second on 8.1.6.X to go faster than 1 minute on 9.2.0.2
I found a new to 9.2.0.X dynamic init parameter " optimizer_dynamic_sampling", if I understand it correctly this parameter forces the optimizer to try harder to get an efficient execution plan. Check the FM there are some interesting things that each level causes the optimizer to do.

-- 
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Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

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Received on Wed Mar 12 2003 - 08:59:16 CST

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