Oracle Consulting Oracle Training Oracle Support Development
Oracle Books
SQL Server Books
IT Books
Job Interview Books
Rampant Horse Books
911 Series
Pedagogue Books

Oracle Software
Write for Rampant
Publish with Rampant
Rampant News
Rampant Authors
Rampant Staff
Oracle News
Oracle Forum
Oracle Tips
Articles by our Authors
Press Releases
SQL Server Books

Oracle 11g Books

Oracle tuning

Oracle training

Oracle support

Remote Oracle


Privacy Policy




Oracle Tips by Burleson 

Two Alternatives for Using CTAS

It is always recommended that you resequence the table rows when performing a table reorganization with CTAS because of the huge I/O benefits. You can use the CTAS statement in one of two ways. Each of these achieves the same result, but they do it in very different ways:

* Use CTAS in conjunction with the order by clause.
* Use CTAS in conjunction with a “hint” that identifies the index to use.

The approach you choose depends on the size of the table involved, the overall processing power of your environment, and how quickly you must complete the reorganization.

The details of each CTAS approach are discussed more fully below, but in either case, when you create the new table, you can speed the process by using the Oracle nologging option (this was called unrecoverable in Oracle7). This skips the added overhead of writing to the redo log file. Of course, you cannot use the redo logs to roll forward through a nologging operation, and most DBAs take a full backup prior to using CTAS with nologging. Let’s examine the two methods and see their respective differences.

The above is an excerpt from the "Oracle9i UNIX Administration Handbook" by Oracle press, authored by Donald K. Burleson.


Download your Oracle scripts now:

The definitive Oracle Script collection for every Oracle professional DBA



Linux Oracle commands syntax poster

ION Oracle tuning software

Oracle data dictionary reference poster

Oracle Forum

BC Oracle consulting support training

BC remote Oracle DBA   



 Copyright © 1996 -2017 by Burleson. All rights reserved.

Oracle® is the registered trademark of Oracle Corporation. SQL Server® is the registered trademark of Microsoft Corporation. 
Many of the designations used by computer vendors to distinguish their products are claimed as Trademarks

Hit Counter