Paul, I think its the other way round, if one of the tables in the query does not contain statistics then Oracle uses RBO. pls correct me if i am wrong. Venu -----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Baumgartel, Paul Sent: 02 March 2006 15:31 To: oracle-l@xxxxxxxxxxxxx Subject: RE: CBO question ? If any table mentioned in the query has statistics stored in the data dictionary, Oracle will use the CBO. Paul Baumgartel paul.baumgartel@xxxxxxxxxxxxxxxxx 212.538.1143 -----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Savio Pinto (s) Sent: Thursday, March 02, 2006 10:28 AM To: oracle-l@xxxxxxxxxxxxx Subject: CBO question ? Hi, The execution plan for a query in oracle 9i shows "Optimizer= CHOOSE", how can i force the DB engine to use the COST based optimization for a query ? Oracle version is 9.2.0.4.0 Thanks Savio Pinto ============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ============================================================================== PLEASE NOTE: THE ABOVE MESSAGE WAS RECEIVED FROM THE INTERNET. On entering the GSi, this email was scanned for viruses by the Government Secure Intranet (GSi) virus scanning service supplied exclusively by Cable & Wireless in partnership with MessageLabs. Please see http://www.gsi.gov.uk/main/notices/information/gsi-003-2002.pdf for further details. In case of problems, please call your organisational IT helpdesk Land Registry at Homebuyer Show, 17-19 March, ExCeL London If you have received this e-mail and it was not intended for you, please let us know, and then delete it. Please treat our information in confidence, as you would expect us to treat yours.The Land Registry checks all mail and attachments for known viruses, however, you are advised that you open any attachments at your own risk. The original of this email was scanned for viruses by the Government Secure Intranet (GSi) virus scanning service supplied exclusively by Cable & Wireless in partnership with MessageLabs. On leaving the GSi this email was certified virus-free