Database Systems: Concepts, Design and Applications

13.5. Recovery Techniques

Database recovery techniques used by DBMS depend on the type and extent of damage that has occurred to the database. These techniques are based on the atomic transaction property. All portions of transactions must be treated as a single logical unit of work, in which all operations must be applied and completed to produce a consistent database. The following two types of damages can take place to the database:

1. Physical damage: If the database has been physically damaged, for example disk crash has occurred, then the last backup copy of the database is restored and update operations of committed transactions are reapplied using the transaction log file. It is to be noted that the restoration in this case is possible ...