RE: performance in 10g

  • From: "MacGregor, Ian A." <ian@xxxxxxxxxxxxxxxxx>
  • To: <davidb158@xxxxxxxxxxx>, <Riazouddine.Rahamathullah@xxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 25 Jan 2007 07:55:37 -0800

If you use alter session and set the optimizer mode to 'rule', how do the 
queries run?  This isn't a proposed solution just a question.  RULE has not 
gone away completely.  

             Alter session set optimizer_mode=rule;

Will invoke the rule optimizer.  I wrote earlier about queries in  support of 
DML such as CTAS or insert into ... Select ... Were horrendously slow, 
althought the queries when separated from the "create" or insert operations ran 
quickly.  I had tried many other things and setting the optimizer to rule for 
the session fixed the problem.  Although in the end as these Oracle devliered 
queries having to do with a Peoplesoft upgrade  were rewritten by Oracle 
rewrote.  We didn't have to use rule to get us through tghat part of the 



-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of David Boyd
Sent: Thursday, January 25, 2007 6:10 AM
To: Riazouddine.Rahamathullah@xxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: performance in 10g


Thanks for your quick response.  We do have the latest stats in place.


>Gather the objects statistics first using DBMS_STATS which will help you
>to improve the performance a lot.  Because, no RBO in oracle 10g and the
>optimizer will give you the optimized plan if your db should have the
>latest stats.

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