RE: hinting and the rule based optimizer
- From: "Justin Cave (DDBC)" <jcave@xxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 1 Apr 2004 13:32:22 -0700
One simple rule-- don't hint (other than /*+ RULE */). By design, any =
hinted statements will invoke the CBO, as will any number of database =
features (i.e. partitioning).
Justin Cave
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx =
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of ryan.gaffuri@xxxxxxx
Sent: Thursday, April 01, 2004 1:04 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: hinting and the rule based optimizer
We have a legacy 8.1.7.3 instance that is in RBO mode. My group does not =
own it, so we cannot change it to CBO.
When I hint anything from an index to ordered, etc... it switches to the =
CBO and since nothing is analyzed, it's an even worse plan... Not =
allowed to analyze the tables either because it's not our property.
Any rules around hinting the RBO in 8.1.7.3? Why would it switch to the =
CBO from a simple hint? I never use the RBO so please bare with me.=20
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