Re: Rule Based Optimization

From: Terry Coccoli <request_at_ifneeded.com>
Date: Fri, 02 Apr 2004 16:25:55 GMT
Message-ID: <nugbc.12259289$Of.2046158@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 - 10:25:55 CST