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 







SQL Cartesian Product Tips

The Cartesian product, also referred to as a cross-join, returns all the rows in all the tables listed in the query.  Each row in the first table is paired with all the rows in the second table.  This happens when there is no relationship defined between the two tables.  Both the AUTHOR and STORE tables have ten rows.  If we use a Cartesian join in these two tables, we will get back 100 rows.   

SQL> select
  2    author_key,
  3    store_key
  4  from
  5    author, store; 
----------- ----
A101        S101
A101        S102
A101        S103
A101        S104
A101        S105
A101        S106
A101        S107
A101        S108
A101        S109
A101        S110
A102        S101
A102        S102
A110        S105
A110        S106
A110        S107
A110        S108
A110        S109
A110        S110 
100 rows selected.

Most of the time, we do not want a Cartesian join, and we end up with one because we failed to provide a filter on the join.  If we actually want a Cartesian join, then we should use the ANSI cross join to tell others reading the script that we actually wanted a Cartesian join.

  author cross join store;

One reason to use a Cartesian join is to generate a large amount of rows to use for testing.  I can take a large table and cross join it to another large table and produce a very large results set.  If I cross join dba_objects and dba_views, I can produce the results set below.

SQL> select count(*)
  2  from
  3    dba_objects cross join dba_views; 

That's a lot of rows!

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.