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Which of the following concurrency control protocols ensure both conflict serializability and freedom from deadlock? I. 2-phase locking II. Time-stamp ordering

Which of the following concurrency control protocols ensure both conflict serializability and freedom from deadlock? I. 2-phase locking II. Time-stamp ordering Correct Answer II only

Key Points

  • 2 PL is based on locks and hence not free from deadlock but ensures conflict serializability.
  • Timestamp ordering protocol is based on timestamps ensures conflict serializability and is also free from deadlock.

Hence the correct answer is II only.

Additional Information

  •  Any schedule is possible under 2PL it must ensure conflict serializability.
  • Deadlock may occur under 2PL.
  • Cascading rollbacks may occur under 2PL.

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