Re: Oracle, Siebel and rule-based optimization

Connor

You're ass-u-ming that what worked for SAP will work for Siebel. Not a good assumption. Been there, done it, it does not work ! What you're advocating, I did similar measures when supporting Ora-Apps when we went from 9.6 to 10.5 (Oracle 7.1.6 RBO to 7.3.2 CBO), what a nightmare that was ! But understand that Siebel was written specifically to take advantage of Oracle's RBO. There has been a team of very talented people at Siebel Engineering ( I refer to James Qiu and his team of REALLY talented whiz kids) who have been working on this holy grail since mid-2001, but still to date, even with release 7.5.2, only RBO is supported. They have had Oracle engineering in there to assist too, but I may not disclose any more than that otherwise I will be in breach of my confidentiality clauses.

I have just completed a 6+ page article on some of the steps for tuning Siebel on Oracle, let me know if you want a copy.

Regards:

Ferenc Mantfeld
Dreaming costs you nothing. Not dreaming costs you everything. ----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Friday, January 31, 2003 7:18 PM

> 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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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Ferenc Mantfeld
  INET: mantfield_at_connexus.net.au

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