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_optimizer_push_pred_cost_based and/or SQL Patch

edited Sep 26, 2017 3:45PM in SQL Performance (MOSC) 11 commentsAnswered

This is a bit of a 'second opinion' on an SR I'm about to get wrapped up.

Here's the issue ...

Testing upgrade from 11.2.0.4 SE-One to 12.1.0.2.0 SE-2.  Testing MV refreshes, and one particular MV consistently takes 3 to 4 minutes to refresh under 11.2, but under 12.1 (even with COMPATIBLE still set to 11.2.0) takes from 12 to 13 hours!

After a lot of back and forth and repeated testing, we ran a test of the mv refresh with the hidden parm "_optimizer_push_pred_cost_based"=false" set at the session level.  That brought the time down to 7 minutes and change.  Still not as good as before, but certainly back to an acceptable time.

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