I'm curious to see the example too. My guess is that the histograms made a difference in the CBO's cardinality estimate, which in turn caused it to choose a different join method or join order. Regards, Brandon ________________________________ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Binh Pham What is the example of histogram without index effects performance? 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.