Re: Oracle, Siebel and rule-based optimization

From: Connor McDonald <hamcdc_at_yahoo.co.uk>
Date: Fri, 31 Jan 2003 00:18:47 -0800
Message-ID: <F001.005401D4.20030131001847@fatcity.com>

One relatively effective way to convert an app from rule to cost is to enable cost in a very "rule-oriented" way (namely, you want indexes to be chosen almost religiously).

You enable cbo but set things like
optimizer_index_cost_adj and optimizer_index_caching to very index favourable values. I remember when SAP went to rule to "cost" and whilst I'm sure some code changes took place I also remember setting the adjust parameter to '10' (instead of 100) so nested loop access was still the dominant access path.

Of course, this all needs testing and your good friends at Siebel would probably not support you - but I've seen it used very successfully a number of times in the past because you get "rule-like" access paths but all the goodies that go with cbo as well.

hth
connor

• Michael Fontana <mfontana_at_verio.net> wrote: >
  >
  > I would like to ask a question of this esteemed and
  > knowledgeable audience
  > about running
  > SIEBEL applications on Oracle. Siebel insists that
  > their CRM application
  > will only run with
  > acceptable performance if rule-based optimization is
  > chosen, yet, as we all
  > know, there are
  > documented examples of poor performance, and strong
  > recommendations to the
  > contrary from Oracle.
  >
  > At one point, I recall reading an article from a
  > knowledgeable consultant
  > describing what must be done
  > to get Siebel to run with optimizer_mode=choose.
  > Any assistance in
  > reaching this goal, or comments,
  > would be more than appreciated. We're still in the
  > implementation phase,
  > and are already receiving
  > poor performance on certain processes, even using
  > the recommended rule
  > based optimization. I
  > predict it will only get worse!
  >
  >
  >
  

  ---

Connor McDonald
web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald_at_yahoo.com

"GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day"

---

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Received on Fri Jan 31 2003 - 02:18:47 CST