From: kennedy-downwithspammersfamily@attbi.net   
      
   "Terry Coccoli"  wrote in message   
   news:nugbc.12259289$Of.2046158@news.easynews.com...   
   > Jim Kennedy wrote:   
   > > "Terry Coccoli"  wrote in message   
   > > news:Gi_ac.12190390$Of.2034190@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 ?   
   >   
   No, because it is rule based.  Also you don't have access to edit the SQL   
   Siebel generates for the system.  You can however use a logon trigger and   
   set up stored outlines.  See Tom Kyte's book for excellent examples of how   
   to do this. (Expert 1 on 1 Oracle)   
      
   Jim   
      
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