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Identify Data Structure required for Database Recovery in Oracle

A redo record contains information that describes a single change to the database. This information includes the bytes before and after the change as well as the transaction number. As a change is made, a redo record is entered in the Redo Log buffer and then flushed to the disk in the online redo logs.

Rollback segments hold information which is used during recovery to remove all uncommitted changes from the datafiles that were applied from the redo logs. Once this is accomplished, the data is considered to be in a consistent state.

This Redo Log Sequence Number is 168. All changes made to the Oracle database are recorded in redo logs. There must be at least two redo logs per database. During database recovery from an instance or media failure, Oracle applies the appropriate changes in the redo logs to the datafiles. This updates the data in the database to the instant that the failure occurred.

The control file is crucial to the functioning of a database. If a control file is not available for writing, then the database will not function properly. The control file is updated continuously while the database is being used. It contains information regarding the physical structure of the database.