_push_join_predicate

Hi,

Is there any harm if I change the value of hidden parameter "_PUSH_JOIN_PREDICATE" to false in oracle 9i. Because my query is taking almost 45 min to get results if _PUSH_JOIN_PREDICATE=true and less than a min when _PUSH_JOIN_PREDICATE=false. I am changing the value of _PUSH_JOIN_PREDICATE in my session using alter session.

Please help, Maheshwar

Quote:

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Originally Posted by maheshwar

Hi,

Is there any harm if I change the value of hidden parameter "_PUSH_JOIN_PREDICATE" to false in oracle 9i. Because my query is taking almost 45 min to get results if _PUSH_JOIN_PREDICATE=true and less than a min when _PUSH_JOIN_PREDICATE=false. I am changing the value of _PUSH_JOIN_PREDICATE in my session using alter session.

Please help, Maheshwar

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Instead of changing the underscore parameter, why don't you tune the SQL statement?

Tamil

You ought to be able to prevent the predicate push at the query level by one of two other methods

• In the in-line view add the clause "and rownum > 1"
• Use the NO_PUSH_PRED ptimizer hint documented here: http://download-west.oracle.com/docs...tsref.htm#6195

Either of these would be preferable to modifying the hidden parameter. Don't forget to document in the query why you have done this.