RE: Risk of RULE mode in 10g+

From: Goulet, Richard <>
Date: Mon, 15 Mar 2010 15:29:53 -0400
Message-ID: <>


    OH Dear, I'll try to find the url that says this for you, but in 10g the rule based optimizer isn't deprecated, it's dead period. You can put rule in there all you want, but it will run in cost mode. Isn't suppose to cause problems with the result set that I've heard of, nor does it cause a problem with executing the sql.  

Dick Goulet
Senior Oracle DBA/NA Team Lead
PAREXEL International  

[] On Behalf Of Jeffrey Zollars Sent: Monday, March 15, 2010 3:22 PM
Subject: Risk of RULE mode in 10g+

We are upgrading an application to the current version and also upgrading the DB version from 9i to 10g. The application code has several bits of code that are explicitly setting RULE mode. One in a configuration table that can be updated. Second, in several hints coded in SQL statements which cannot be easily changed.

I have provided Oracle documentation to the application vendor showing that RULE mode is desupported in 10g+ versions. They were skeptical to say the least.

I had thought that I'd seen stronger warnings that RULE mode could actually generate incorrect result sets when running queries. I have searched but could not find those warnings now. I am trying to make a case to request the application vendor to go back and modify the code before we update to the current version of the application on Oracle version. I'm concerned about the integrity of the result sets.

I am wondering if anyone knows of or can provide a link to the warning that result sets may be incorrect in 10g+ using RULE mode.


J. A. Zollars 

Received on Mon Mar 15 2010 - 14:29:53 CDT

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