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dynamic sampling precedence [message #644365] Tue, 03 November 2015 14:48 Go to next message
kal_youssef
Messages: 25
Registered: September 2005
Location: canada
Junior Member
I would like to know if I have the following set then which takes precedence?

OPTIMIZER_DYNAMIC_SAMPLING=2
OPTIMIZER_USE_SQL_PLAN_BASELINES=TRUE
OPTIMIZER_ADAPTIVE_REPORTING_ONLY=FALSE

I tried searching in the oracle documents but there is no mention of which parameter takes precedence in adaptive plans / dynamic sampling




thanks
Kal

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Re: dynamic sampling precedence [message #644366 is a reply to message #644365] Tue, 03 November 2015 14:53 Go to previous messageGo to next message
BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal
Senior Member
If you really want to learn the answer, trace CBO decision making using below

https://www.google.com/webhp?hl=en&tab=ww#hl=en&q=oracle+cbo+trace

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Re: dynamic sampling precedence [message #644367 is a reply to message #644365] Tue, 03 November 2015 16:12 Go to previous message
John Watson
Messages: 8964
Registered: January 2010
Location: Global Village
Senior Member
Using baselines should stabilize the system: no new exec plans will be used (until successfully evolved). That effectively precludes re-optimization, no matter you do with the other parameters.

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