Check if you have objects statistics collected. -----Original Message----- From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Peter Dixon Sent: Tuesday, July 11, 2006 1:43 PM To: oracle-l@xxxxxxxxxxxxx Subject: Oracle 10g upgrade - performance issue Help! Upgraded 8.1.7.4 to 10g rel 2 smoothly over the weekend. Batch works fine, but OLTP is causing CPU and disk i/o to max out at 100%, i believe the optimiser is making bad decisions as my introducing rule hints the problem has slightly improved. Any ideas as our SR with Oracle says "tune the code" also we never got the issues in test. Peter Dixon -- //www.freelists.org/webpage/oracle-l -- //www.freelists.org/webpage/oracle-l