Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Re: Oracle position on hints 9.2.0.X

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

Now available One-day tutorials:
  Cost Based Optimisation
  Trouble-shooting and Tuning
  Indexing Strategies

(see http://www.jlcomp.demon.co.uk/tutorial.html )

____UK_______March 19th
____UK_______April 8th
____UK_______April 22nd

____USA_(FL)_May 2nd

Next dates for the 3-day seminar:
(see http://www.jlcomp.demon.co.uk/seminar.html )

____UK_(Manchester)_May
____USA_(CA, TX)_August

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

After spending 2 ½ 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.

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).
Received on Wed Mar 12 2003 - 08:59:16 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US