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?
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- The same undo and redo list will be used while recovering again.
- The system cannot recover any further.
- All the transactions that are already undone and redone will not be recovered again.
- The database will become inconsistent.
The Correct Option is A
Solution and Explanation
Step 1: Effect of crash during recovery.
When a database crashes during recovery and no checkpointing is used, the recovery process must restart from the beginning using the log.
Step 2: Undo and redo lists.
Since there is no checkpoint to record progress, the system cannot determine which undo or redo actions were completed before the second crash. Hence, the same undo and redo lists are reconstructed and applied again.
Step 3: Evaluation of options.
Statement (A) is correct because recovery restarts with the same undo and redo lists.
Statement (B) is incorrect since recovery is still possible.
Statement (C) is incorrect because operations may be repeated without checkpointing.
Statement (D) is incorrect because recovery mechanisms ensure consistency.
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