RE: Plan stability with rule based optimzier
- From: "Lex de Haan" <lex.de.haan@xxxxxxxxxxxxxx>
- To: <lex.de.haan@xxxxxxxxxxxxxx>, <JBECKSTROM@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>, <oracle-db-l@xxxxxxxxxxxxxxxxxxxx>, <ORACLE-L@xxxxxxxxxxxxx>, <oracledba@xxxxxxxxxxx>, <oracle-rdbms@xxxxxxxxxxxxxxx>
- Date: Fri, 11 Feb 2005 15:57:39 +0100
sorry -- I was trying to say two things at the same time.
The CHOOSE hint only kicks in CBO if statistics are available,
because otherwise it would default back to RULE, making the hint useless.
Therefore I assumed the presence of object statistics.
So if the intent is to deviate from RULE behavior for a specific SQL
statement,
using ALL_ROWS or FIRST_ROWS(n) is the preferred method.
Lex.
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Lex de Haan
Sent: Friday, February 11, 2005 15:52
To: JBECKSTROM@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx;
oracle-db-l@xxxxxxxxxxxxxxxxxxxx; ORACLE-L@xxxxxxxxxxxxx;
oracledba@xxxxxxxxxxx; oracle-rdbms@xxxxxxxxxxxxxxx
Subject: RE: Plan stability with rule based optimzier
of course you can do that -- the hint will unconditionally kick in the CBO.
I think it is better to throw in an ALL_ROWS or FIRST_ROWS(n) hint, by the
way.
Lex.
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Jeffrey Beckstrom
Sent: Friday, February 11, 2005 15:09
To: oracle-l@xxxxxxxxxxxxx; oracle-db-l@xxxxxxxxxxxxxxxxxxxx;
ORACLE-L@xxxxxxxxxxxxx; oracledba@xxxxxxxxxxx; oracle-rdbms@xxxxxxxxxxxxxxx
Subject: Plan stability with rule based optimzier
Before going to far, I want to make sure this will work.
Our database is running with RULE set at the database level. We would like
to tune an SQL statement in a third party application by using a stored
outline. For the sql in question, we are going to add a "Choose"
database hint.
Is it possible to use stored outlines if the database is running in RULE
mode?
Jeffrey Beckstrom
Database Administrator
Greater Cleveland Regional Transit Authority 1240 W. 6th Street Cleveland,
Ohio 44113
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