Re: Rule Based Optimization

From: Jim Kennedy <kennedy-downwithspammersfamily_at_attbi.net>
Date: Thu, 01 Apr 2004 22:50:36 GMT
Message-ID: <011bc.154503$1p.1987422@attbi_s54>

"Terry Coccoli" <request_at_ifneeded.com> wrote in message news:Gi_ac.12190390$Of.2034190_at_news.easynews.com...
> We have a Siebel implementation and for one query that was taking a long
> time to run I asked a DBA to evaluate the explain plan. I noticed that
> he chose to evaluate the Rule based optimization. I asked him why and
> he said that the Siebel application defaults to Rule based optimization.
>
> Not that I don't trust him, but I had the impression that Cost based was
> the way to go.
>
> Is it possible to set up a database schema so that it the optimizer
> always uses Rule based rather than Cost ? And if anyone knows Siebel,
> is this the actual default ?
>
>
> Thanks.
>

Siebel is rule based.
They are about 5 years behind in taking advantage of the database technology that the system runs on. Yes, cost is the way to go but not with Siebel. They won't support you if you use rule based. (which means you can't do a whole bunch of things) One thing that you can do to get around this is that if you have a specific query that is better under cost based you can use a stored outline. (get Thomas Kyte's book) Jim Received on Thu Apr 01 2004 - 16:50:36 CST