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Oracle Database 12c Backup and Recovery Survival Guide

You're reading from   Oracle Database 12c Backup and Recovery Survival Guide A comprehensive guide for every DBA to learn recovery and backup solutions

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Product type Paperback
Published in Sep 2013
Publisher Packt
ISBN-13 9781782171201
Length 440 pages
Edition 1st Edition
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Toc

Table of Contents (22) Chapters Close

Oracle Database 12c Backup and Recovery Survival Guide
Credits
About the Author
Acknowledgement
About the Author
Acknowledgement
About the Reviewers
www.PacktPub.com
Preface
1. Understanding the Basics of Backup and Recovery 2. NOLOGGING Operations FREE CHAPTER 3. What is New in 12c 4. User-managed Backup and Recovery 5. Understanding RMAN and Simple Backups 6. Configuring and Recovering with RMAN 7. RMAN Reporting and Catalog Management 8. RMAN Troubleshooting and Tuning 9. Understanding Data Pump 10. Advanced Data Pump 11. OEM12c and SQL Developer Scenarios and Examples – A Hands-on Lab Index

Some other important facts


In this section we will talk about some other important facts about redo that are important for you to know.

Redo and undo for DML

When you issue an insert, update, or delete, Oracle actually makes the change to the data blocks that contain the affected data even though you have not issued a commit. To ensure database integrity, Oracle must write information necessary to reverse the change (undo) into the redo log file to handle any transaction failure or even a rollback. Recovery from media failure is ensured by writing the information necessary to replay all database changes (redo) to the database into the redo log file. So, undo and redo information needs to be written into the transaction log of the RDBMS as a logical consequence to protect the integrity of the data.

While the RDBMS logically would only need to write undo and redo into the transaction log, the undo portion must also be kept online (on disk and accessible to the RDBMS engine) to enable rollback...

You have been reading a chapter from
Oracle Database 12c Backup and Recovery Survival Guide
Published in: Sep 2013
Publisher: Packt
ISBN-13: 9781782171201
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