In the two-phase locking protocol:
A) A transaction only acquires a lock after the previously acquired lock has been released
B) A transaction acquires locks as needed. After it starts releasing locks, it does not acquire new locks
C) A transaction acquires all needed locks at once, then releases them after completion
D) The transaction locks the full database, then releases the locks

Question

Quizplus · Accepted Answer

In the two-phase locking protocol, a transaction acquires locks as needed but cannot acquire any new locks after it starts releasing locks. This ensures that the transaction cannot read or write data that another transaction might be modifying, thus preventing conflicts and ensuring serializability. Releasing locks as soon as possible also helps to reduce the likelihood of deadlocks. Therefore, option B is the best choice.

In the Two-Phase Locking Protocol