Choose the correct description of database rollforward recovery processing:

Rollforward recovery (also called roll-forward or redo recovery) is the process of reapplying committed transactions from the redo log to restore a database to its state before a failure. After a physical media failure, the backup is restored and then all committed transactions recorded in the redo log are reapplied to bring the database current. Options B, C, and D describe unrelated database operations: B is rollback (undo) recovery, C is an index optimization that is not recovery, and D is a schema modification unrelated to recovery.

Step-by-step Derivation:
Rollforward recovery mechanism:

1. A physical media failure occurs (disk crash, corruption, etc.)
2. The database is restored from a backup taken at an earlier checkpoint
3. The redo log (transaction log) is consulted to identify all committed transactions that occurred after the backup
4. Those committed transactions are replayed/reapplied to the restored database
5. This brings the database to its state just before the failure

This is distinct from:

• Rollback: undoing uncommitted transactions (Option B uses undo log, not redo log)
• Index management: deleting indexes (Option C) has no recovery purpose
• Schema changes: dropping constraints (Option D) is not a recovery operation

Therefore, Option A correctly describes rollforward recovery.