Which of the following correctly describes backward recovery in database systems?

Correct option is A

Backward Recovery, also known as rollback recovery, involves reverting the database to a previous consistent state by applying the before-images (data stored before any changes) from the transaction logs. This method is used to undo uncommitted changes in the event of a system failure or transaction abort.
Important Key Points:
1. Before-images: These are snapshots of data taken before a transaction begins. They are crucial for restoring the database to its previous state.
2. Forward Recovery: Uses after-images to bring the database to the latest consistent state after a failure.
3. Backward Recovery ensures that incomplete or erroneous transactions do not affect database consistency.
Knowledge Booster:
· Transaction Logs: Logs containing before- and after-images are essential for implementing recovery mechanisms.
· ACID Properties: Backward recovery is crucial for maintaining the Consistency and Atomicity of transactions in databases.
· Checkpointing: A process in DBMS where a snapshot of the database is taken to reduce the recovery time.