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Media Recovery

If you rcstorc thc archi vcd redo log files and data filcs, then you must perform media recovery before you can open the databasc. Any databasc transactions in the archivcd redo log filcs not rcflectcd in the data filcs are applied to the data files, bringing them to a transaction-consistent State before thc databasc is opened.

Media recovcry requires a control file, data files (typically restored front backup), and online and archived redo log files containing changes sińce thc time the data files were backed up. Media recovery is most often uscd to recover from media failure, such as the loss of a file or disk. or a user error, such as the deletion of the contents of a table. Media recovery can be a complete recovery or a point-in-time recovery. Complete recovery can apply to individual datafiles, tablespaces, or the entire databasc. Point-in-time recovery applies to the whole databasc (and also sometimes to individual tablespaces, with automation help from RMAN).

In a complete recovery, you restore backup data files and apply all changes from the archived and online redo log files to the data files. The database is returned to its State at the time of failure and can be opened with no loss of data.

In a point-in-time recovery, you return a database to its contents at a user-selected time in the past. You restore a backup of data files created before the target time and a complete set of archived redo log files from backup creation through the target time. Recovery applies changes between the backup time and the target time to the data files. All changes after the target time are discarded.

RMAN enablcs you to perform both a complete and a point-in-time recovcry of your database. Howcvcr. this documcntation focuses on complete rccovcry.