Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 E-mail Us
 Oracle Articles
New Oracle Articles

 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog

 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Oracle Support

 SQL Tuning

 Oracle UNIX
 Oracle Linux
 Remote s
 Remote plans
 Application Server

 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S


 Consulting Staff
 Consulting Prices
 Help Wanted!


 Oracle Posters
 Oracle Books

 Oracle Scripts

Don Burleson Blog 







Oracle _optimizer_ignore_hints tips

Oracle Database Tips by Donald BurlesonFebruary 10, 2015

The _optimizer_ignore_hints enables all embedded SQL hints to be ignored, very handy when testing optimizer behavior.  Oracle provides the _optimizer_ignore_hints hidden initialization parameter to provide workarounds for system-wide issues.

For example, some ancient Oracle applications are plagued with /*+ rule */ hints embedded into the SQL, and setting _optimizer_ignore_hints allows these statements to execute under the cost-based optimizer.

The _optimizer_ignore_hints parameter to correct an issues with SQL optimization and ODBC when they migrated to Oracle 10.2.  

"The rule based optimizer, which the Oracle ODBC driver is using, was deprecated in Oracle 10.1. For some reason the rule based optimizer performs the statements OK on 10.1 but terribly on 10.2.

This is documented on Oracle MOSC (Note 373129.1). The Oracle bug is 4150034 and is fixed in patch 5211342. Unfortunately this fix involves updating and patching the Oracle ODBC driver, which would require an update to every PC in the organization.

A better solution we discovered was to create a logon trigger to set the _optimizer_ignore_hints parameter to true for all sessions connecting to the database via the ODBC application."

Get the Complete
Oracle SQL Tuning Information 

The landmark book "Advanced Oracle SQL Tuning  The Definitive Reference"  is filled with valuable information on Oracle SQL Tuning. This book includes scripts and tools to hypercharge Oracle 11g performance and you can buy it for 30% off directly from the publisher.



Oracle Training at Sea
oracle dba poster

Follow us on Twitter 
Oracle performance tuning software 
Oracle Linux poster


Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


Copyright © 1996 -  2020

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.