Performance degradation after upgrading from 10gR2 to 11gR2

No hard feelings :)

Quote:

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Originally Posted by gandolf989

Is that like pressing the easy button? It looks like your parameter does not help if you already use ASM.

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Only works with "cooked" disk (not ASM).
The main problem was occurring due to Linux disk "cache" and the parameter allowed Oracle to bypass the OS file manager.
;)

Hi guys,

I wanted to update that after a long session with Oracle Support via SR , they decided that this behavior is a bug in 11.2.0.3 and they are developing now a fix.
Bug 17397506 : SORT MERGE INCORRECTLY CHOSEN OVER HJ IN 11.2.0.3
The workaround that I've got from them:
Setting the parameter _optimizer_filter_pushdown to FALSE.
For testing this parameter , I've applied it in session level (by a trigger) on a group of customers.
Most of the screwed reports were improved but there were several reports that their good explain plan was screwed because of this parameter.We tread them with hints.

Regards,
Nir