Not sure if you already saw this, but here is the list of "supported" parameters, which another member referred to earlier, however as Dion mentioned, the hint seems to work for more than just these supported parameters, but apparently you just have to guess as to which ones work and which ones don't - I couldn't find a list anywhere on the Internet or on MOS. http://download.oracle.com/docs/cd/E11882_01/server.112/e10592/sql_elements006.htm#SQLRF51119 "This hint is valid only for the following parameters: OPTIMIZER_DYNAMIC_SAMPLING, OPTIMIZER_INDEX_CACHING, OPTIMIZER_INDEX_COST_ADJ, OPTIMIZER_SECURE_VIEW_MERGING, and STAR_TRANSFORMATION_ENABLED" Just one more thing - did you try it without putting 9.2.0 in quotation marks? From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of LS Cheng Does anyone know if there is a list which contains parameters supported by OPT_PARAM :-? ________________________________ 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.