As so many of the statements executed against a database generate undo data, managing it is a crucial aspect of database administration. In the past, Oracle used resources called rollback segments
to manage undo data. When a user connected to the database, they were assigned a rollback segment that would serve as storage for the undo data (called rollback data
, back then) generated by that session. Unfortunately, these rollback segments were fairly finite in size, sometimes leading to the infamous ORA-1555 error, "snapshot too old". This error was raised in situations where queries encountered an undo block that had been overwritten since the query was initiated. In version 9i, Oracle introduced new, more efficient ways to manage undo data, leading to fewer errors. This new approach has also allowed for new features that can use undo data even after it is expired following a COMMIT statement.
OCA Oracle Database 11g: Database Administration I: A Real-World Certification Guide
OCA Oracle Database 11g: Database Administration I: A Real-World Certification Guide
Overview of this book
Oracle Database Server is the most widely used relational database in the world today. This book gives you the essential skills to master the fundamentals of Oracle database administration and prepares you for Oracle DBA certification."OCA Oracle Database 11g: Database Administration I: A Real-World Certification Guide" prepares you to master the fundamentals of Oracle database administration using an example driven method that is easy to understand. The real world examples will prepare you to face the daily challenges of being a database administrator.Starting with the essentials of why databases are important in today's information technology world and how they work, you are then guided through a full, customized installation of the Oracle software and creating your own personal database. We then examine fundamental concepts of Oracle, including architecture, storage structures, security, performance tuning, networking, and instance management. Finally, we take an in-depth look at some of the most important concepts in the daily life of an Oracle DBA - backup, recovery, and data migration."OCA Oracle Database 11g: Database Administration I: A Real-World Certification Guide" provides you with the skills you need in order to become a successful Oracle DBA, both for certification and real life tasks.
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Table of Contents (24 chapters)
OCA Oracle Database 11g: Database Administration I: A Real-World Certification Guide
Credits
Foreword
About the Author
About the Reviewer
www.packtpub.com
Preface
Free Chapter
Introducing the Oracle Relational Database System
Installing the Oracle Database Software
Creating the Oracle Database
Examining the Oracle Architecture
Managing Oracle Storage Structures
Managing the Oracle Instance
Managing Security
Managing Concurrency
Configuring an Oracle Network
Managing Database Performance
Understanding Backup and Recovery Concepts
Performing Database Backups
Performing Database Recovery
Migrating Data
Preparing for the Certification Exam
Test Your Knowledge – Answers
Index
Customer Reviews