11.8 Recovery Techniques
Transactions are used as the basic unit for recovery for a database. The DBMS has a recovery manager that is responsible for ensuring atomicity and durability for transactions in the event of failure. Atomicity requires that all operations of a transaction be performed successfully or none, so the recovery manager must ensure that all the effects of committed transactions reach the database, and that the effects of any uncommitted transactions are undone as part of recovery. Durability requires that the effects of a committed transaction be permanent, so they must survive the loss of main memory, loss of disk storage, and failures during data transfers to disk.
The possible loss of disk data is handled by doing frequent ...
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