Statement III: Timestamp ordering protocol ensures serializability based on the order of transaction timestamps.
Which of the following is correct?
1.Statement I, Statement II true and Statement III false
2.Statement I, Statement III true and Statement II false✓ Correct
3.Statement I, Statement II false and Statement III true
4.Statement I, Statement II and Statement III true
Solution
Solution:
Statement I: True
Conservative Two-Phase Locking (2PL) protocol requests all required locks at once, and proceeds only if all are granted. This avoids circular wait, thereby ensuring a deadlock-free execution.
Statement II: False
Thomas's write rule is used to ignore obsolete writes in timestamp-based concurrency control. While it improves concurrency, it does not enforce conflict serializability. It can allow schedules that are not conflict-serializable.
Statement III: True
Timestamp ordering protocol ensures conflict serializability by ordering all operations based on their assigned timestamps. Transactions are executed in a way that maintains the logical timestamp order.
Final Answer:
Option 2: Statement I and III are true, Statement II is false.