Re: Rule Based Optimization
Date: Fri, 02 Apr 2004 16:25:55 GMT
Message-ID: <nugbc.12259289$Of.2046158_at_news.easynews.com>
Jim Kennedy wrote:
> "Terry Coccoli" <request_at_ifneeded.com> wrote in message
> news:Gi_ac.12190390$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 > >
What happens if you throw in a hint like FIRST_ROWS? Would the optimizer accept the hint ? Received on Fri Apr 02 2004 - 18:25:55 CEST