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 







pct_direct_access Tips

Oracle Database Tips by Donald BurlesonJune 13, 2015

Question: I see some recommendations that the value in for an IOT may indicate that the IOT may require rebuilding.  Is the value of pct_direct_access in dba_indexes an important metric to monitor for rebuilding an index-only tablespace?

Answer:  As we know, an index-only table (IOT) is a type of table where Oracle stored the non-index columns in the index tree, rather than in a separate table segment. While the key for an IOT is usually the table primary key, an IOT allows the DBA to create other secondary indexes on the IOT just as if it were a real table.  

Internally, Oracle uses the value of pct_direct_access to see how to access a table.  Each index on an IOT contains a value in dba_indexes pct_direct_access and Oracle uses this data to determine whether he should use a ROWID fetch through the IOT tree, or do a fetch against a secondary index on a column value.  

The value for pct_direct_access is not dynamic and pct_direct_access is gathered as of the last time that the SMON background process gathered I/O information.  

Some experts suggest that when the value for pct_direct_access gets sufficiently low, the index should be rebuilt.  Others periodically rebuild all indexes with fully automated scripts during scheduled maintenance windows (evenings/ weekends/holidays) because an index rebuild is 100% safe when executed properly.  

For general tips on the threshold for index rebuilding, see the latest consensus on index rebuilding.

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.




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.



Oracle Training at Sea
oracle dba poster

Follow us on Twitter 
Oracle performance tuning software 
Oracle Linux poster