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Overview of Database Backup and Recovery

The focus in Oracle Database backup and recovcry is on the physical backup of database files, which permits you to rcconstruct your database. RMAN, a command-line tool, is the method preferred by Oracle for efficiently backing up and rccovering your Oracle database. The files protectcd by the backup and rccovery facilities built into RMAN inelude data files. control files. scrver parameter files. and archived redo log files. With these files you can rcconstruct your database. RMAN is designed to work intimately with the server, providing block-level corruption detection during backup and restore. RMAN optimizes performance and space consumption during backup w ith file multiplexing and backup set compression, and integrates with leading tape and storage media produets. The backup mechanisms work at the physical level to protect against file damage, such as the accidental deletion of a data file or the failure of a disk drive. RMAN can also be used to perform Logical backups, such as exporting database objects such as tables or tablespaces, are a

useful supplcment to physical backups. but cannot protect your wholc database. An cffcctivc backup strategy must be based on physical backups.

The Oracle Database flashback fcaturcs providc a rangę of physical and logical data rccovcry tools as cfficicnt, casy-to-usc altcrnatives to physical and logical backups. The

flashback fcaturcs enable you to rcvcrsc the effeets of unwanted database changcs without restoring data files from backup.

This section introduces the following flashback features:

■Oracle Flashback Table, which enables you to revert a table to its contents at a time in the recent past

■Oracle Flashback Drop. which enables you to retrieve deleted (dropped) database tables

■Oracle Flashback Database, which enables you to revert the entire database to a past point in time

The first two features operate at the logical level, whereas the last feature operates at the physical level. Nonę of the preceding features requires advance preparation such as creating logical cxports to allow for retrieval of your lost data, but Oracle Flashback Database requires the advance preparation of enabling the feature. You can use all of the features w'hile your database is availabie. Oracle Database Backup and Recovery User's Guide discusses the flashback features of Oracle Database at greater length.