Suppose a database system crashes again while recovering from a previous crash. Assume checkpointing is not done by the database either during the transactions or during recovery. Which of the following statements is/are correct?

In log-based database recovery without checkpointing: [cite: 1]

1. Idempotency of Recovery: Redo and undo operations are designed to be idempotent, meaning executing them multiple times produces the exact same result as executing them once.

2. State of the Log: Since checkpointing is not performed during normal transaction processing or during recovery, the log on stable storage remains the same as before the recovery started.

3. Recovery Restart: When the system restarts after the second crash, it scans the log from the very beginning. Because the log has not changed and no checkpoint records were inserted, the recovery manager constructs the exact same undo-list and redo-list.

Therefore:

• (A) is correct: The same undo and redo list will be used while recovering again [cite: 1].

• (B) is incorrect: The system can successfully recover because redo and undo actions are idempotent.

• (C) is incorrect: Transactions will be processed again according to the same lists.

• (D) is incorrect: Once the recovery process eventually finishes, the database is restored to a consistent state.