Wolfgang I am not good in reading the trace and so using ORasrp as well as your site to understand the steps. Your site has great paper on the CBO behaviour Tx Wolfgang Breitling <breitliw@xxxxxxxxxxxxx> wrote: At 12:39 AM 2/20/2007, Syed Jaffar Hussain wrote: Sanjay, I do agree with Wolfgang Breitling. However, if you are on 10g, I would suggest to enable event 10132 in place of 10053. http://jonathanlewis.wordpress.com/2006/11/27/event-10132/ However, that will only give you the comparison of the optimizer parameters, not the comparison of whether and where the base table cardinality estimates differ as well as other differences in the way the CBO assembles the access plans. Regards Wolfgang Breitling Centrex Consulting Corporation www.centrexcc.com ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ --------------------------------- Never miss an email again! Yahoo! Toolbar alerts you the instant new Mail arrives. Check it out.