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

Oracle Software
image
Write for Rampant
Publish with Rampant
Rampant News
Rampant Authors
Rampant Staff
 Phone
 800-766-1884
Oracle News
Oracle Forum
Oracle Tips
Articles by our Authors
Press Releases
SQL Server Books
image
image

Oracle 11g Books

Oracle tuning

Oracle training

Oracle support

Remote Oracle

STATSPACK Viewer

Privacy Policy

 

   
  Oracle Tips by Burleson

OCP Instructors Guide for Oracle DBA Certification

Chapter 5 - Oracle Database Objects

Oracle9i External Tables

Before Oracle9i, the most common methods of manually performing complex transformations were:

  • The extracted data would be loaded into staging tables in the data warehouse. The staged data would be transformed in the database and then used as input to programs that updated the permanent data warehouse tables.
     

  • The data would be transformed in flat files stored outside of the database. When the transformation process was complete, the data would be loaded into the data warehouse.

Oracle9i introduces external tables, which provide a mechanism to view data stored in external sources as if it were a table in the database. This ability to read external data provides a more straightforward method of loading and transforming data from external sources. Administrators no longer need to reserve space inside the database for staging tables or write external programs to transform the data outside of the database environment. By making it no longer necessary to stage data in the Oracle database, Oracle9i’s external tables have essentially streamlined the ETL function by merging the transformation and loading processes.

External tables in Oracle are read-only and cannot have indexes built upon them. Their main use is a data source for more traditional Oracle table structures. Data warehouse administrators are able to use the CREATE TABLE AS SELECT…. and the INSERT INTO…..AS SELECT statements to populate Oracle tables using the external source as input.
 


The above text is an excerpt from:


OCP Instructors Guide for Oracle DBA Certification
A Study Guide to Advanced Oracle Certified Professional Database
Administration Techniques

ISBN 0-9744355-3-8

by Christopher T. Foot
 

http://www.rampant-books.com/book_2003_2_OCP_print.htm


Download your Oracle scripts now:

www.oracle-script.com

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 -2016 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