Here is another good article on this topic (troubleshooting bad cardinality estimates and explain plans) from Greg Rahn, an Oracle insider and frequent contributor to this list: http://structureddata.org/2007/11/21/troubleshooting-bad-execution-plans/ Regards, Brandon ________________________________ Privileged/Confidential Information may be contained in this message or attachments hereto. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of this company shall be understood as neither given nor endorsed by it.