Oracle Scratchpad

February 26, 2014

Predicate Order

Filed under: Bugs,CBO,Execution plans,Oracle — Jonathan Lewis @ 8:14 am BST Feb 26,2014

Common internet question: does the order of predicates in the where clause make a difference.
General answer: It shouldn’t, but sometimes it will thanks to defects in the optimizer.

There’s a nicely presented example on the OTN database forum where predicate order does matter (between 10.1.x.x and 11.1.0.7). Note particularly – there’s a script to recreate the issue; note, also, the significance of the predicate section of the execution plan.
It’s bug 6782665, fixed in 11.2.0.1

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