CPU costing is off

Just a quick note that if you see in your executions plans via DBMS_XPLAN that “CPU costing is off”, then it might not be, you might just have old versions of PLAN_TABLE hanging around.

I’ve just spent a little while trying to figure out why CPU costing might be off, after which a quick drop of a local PLAN_TABLE fixed everything.

So, not so much that CPU costing was off, more that some of the CPU costing information was not available in the PLAN_TABLE.

Interestingly, I did NOT have a message saying that “‘PLAN_TABLE’ is old version”.

I did spend a few minutes trying to recreate the situation with old versions of PLAN_TABLE locally, but all I could get was a message that PLAN_TABLE was old version, nothing about cpu costing being off. Bit weird but probably not worth spending any more time over.

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