Advanced Locking Protocols

The locking protocols presented thus far assume that the lockable units of the database are single tuples. Such a choice is appropriate to transactions that access a few tuples only. If a transaction accesses many tuples, it must also acquire many locks. Each such access incurs the computational overhead of requesting and perhaps waiting for the granting of the lock, and, in the case of a huge number of commit-duration locks, the storage overhead on storing the locks in the lock table until the commit of the transaction.