What is an incomplete recovery?

What is an incomplete recovery?

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An incomplete recovery is a type of media recovery in which only a part of redo data is applied to a restored backup in order to bring it to a specified state prior to the media failure. A database must be running in ARCHIVELOG mode in order to perform an incomplete recovery. An incomplete recovery is usually performed when the requirement is to recover up until some point-in-time before an incorrect action occurred in the database. For example, if a user mistakenly drops a table, the database administrator will be required to restore the whole database and perform an incomplete recovery up to a point-in-time just before the user dropped the table.

An incomplete recovery is also performed in the following situations:

Online redo logs are lost due to disk failure: In this case, the database can be recovered until the last archived log was generated before the failure.

An archived redo log file required for complete recovery is missing: In this case, the only option is to recover up to the missing archived redo log file.

The current control file is lost: In this case, recovery can be performed by restoring a backup of the control file.

To perform an incomplete recovery of a database, all data files must be restored from a backup taken prior to the time to which the database is to be recovered. Also, all the data files and not only the damaged or lost data files need to be restored for performing an incomplete recovery. After performing an incomplete recovery, the database must be opened with the RESETLOGS option. Opening the database with the RESETLOGS option creates a new incarnation of the database, resetting the log sequence number to 1.

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