nptel

Question

Which of the following statement is correct ?

1. 2 phase locking protocol does not suffer with problem of cascading rollback
2. Strict 2 phase protocol never results in deadlock
3. In strict 2 phase protocol, restriction of releasing exclusive locks until commit ensures no cascading rollbacks
4. Time-stamp ordering protocol can generate non-recoverable schedules

Comments

1. 2 phase locking protocol does not suffer with problem of cascading rollback : False( it must be strict 2pl.)
2. Strict 2 phase protocol never results in deadlock. False ( It can be in deadlock)
3. In strict 2 phase protocol, restriction of releasing exclusive locks until commit ensures no cascading rollbacks. True
4. Time-stamp ordering protocol can generate non-recoverable schedules. False ( always recoverable)

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4 .if timestamp is strict then it only give recoverable schedule as they are cascadless. but, Basic time stamp only ensure serilizablity not recoverable it may be non-recoverable.