Re: The exact difference between SQL profile and baselines in Oracle 11

From: TheBoss <>
Date: 10 Oct 2011 21:56:21 GMT
Message-ID: <Xns9F7AF386D56EATheBossUsenet_at_194.109.133.133>

Mladen Gogala <> wrote in

> On Mon, 10 Oct 2011 19:09:08 +0200, Robert Klemme wrote:

>> I think a baseline contains the data on which profile creation is
>> based: 

> Baselines are plans. Profiles contain hints and therefore are used to
> influence plans. My problem is what happens when I have both. Will
> profiles influence the plans determined by baselines? What is the
> exact mechanism? Oracle has several mechanisms covering roughly the
> same area: outlines, profiles and baselines. I am trying to develop
> test cases to see what happens in the different situations, but it's
> slow. What I'm asking for is if somebody else has done that research.


Oracle's Optimizer Development team has written a very interesting 4-part serie of articles on their blog on the subject of SQL Plan Management: _creating_sql_plan_baselines _spm_aware_optimizer _evolving_sql_plan_baselines_1 _user_interfaces_and_other_features

Parts 3 and 4 have examples of Baselines and Profiles working together for optimal results. As you also mentioned Outlines: They fairly recently wrote a blog article on why you should migrate them (especially if you're on 11g) to Baselines and how to do that:

if you don't mind reading articles from bottom to top, you can use following link to get all articles mentioned above in one go:

HTH Cheers!

Received on Mon Oct 10 2011 - 16:56:21 CDT

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