Re: The exact difference between SQL profile and baselines in Oracle 11
From: Robert Klemme <shortcutter_at_googlemail.com>
Date: Mon, 10 Oct 2011 19:09:08 +0200
Message-ID: <9fgn5lF8pcU1_at_mid.individual.net>
On 10.10.2011 18:17, Mladen Gogala wrote:
> I must say that I'm not quite clear about the conceptual differences
> among the two. I know that SQL Profiles put in a lot of OPT_ESTIMATE
> hints and adjust cardinality estimates. I know that baselines are
> actually plans but their usage seems extremely similar. Can anyone shed
> some light on the conceptual differences?
Date: Mon, 10 Oct 2011 19:09:08 +0200
Message-ID: <9fgn5lF8pcU1_at_mid.individual.net>
On 10.10.2011 18:17, Mladen Gogala wrote:
> I must say that I'm not quite clear about the conceptual differences
> among the two. I know that SQL Profiles put in a lot of OPT_ESTIMATE
> hints and adjust cardinality estimates. I know that baselines are
> actually plans but their usage seems extremely similar. Can anyone shed
> some light on the conceptual differences?
I think a baseline contains the data on which profile creation is based:
http://download.oracle.com/docs/cd/E11882_01/server.112/e16638/autostat.htm#autoId15
The more abstract definition
http://download.oracle.com/docs/cd/E11882_01/server.112/e16638/perf_overview.htm#autoId4
As I understand it the baseline contains the base data which is used to identify critical SQL which then is further analyzed during maintenance windows. IIRC you can even have Oracle automatically accept new plans (probably stored in profiles) if the execution characteristics improve vs. the current plan.
http://download.oracle.com/docs/cd/E11882_01/server.112/e16638/sql_tune.htm#CHDHICFI
Kind regards
robert
-- remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/Received on Mon Oct 10 2011 - 12:09:08 CDT