Oracle Scratchpad

February 26, 2014

Predicate Order

Filed under: Bugs,CBO,Execution plans,Oracle — Jonathan Lewis @ 8:14 am GMT 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 that the thread includes a script to recreate the issue; note, also, the significance of the Predicate Information section of the execution plan.

It’s bug 6782665, fixed in 11.2.0.1

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