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Last Updated on 03/19/2023 by Sophia

Consider the multiple-granularity locking protocol described in Chapter 18. In a distributed DBMS the site containing the root object in the hierarchy can become a bottleneck. You hire a database consultant who tells you to modify your protocol to allow only intention locks on the root, and to implicitly grant all possible intention locks to every transaction.

1. Explain why this modification works correctly, in that transactions continue to be able to set locks on desired parts of the hierarchy.

2. Explain how it reduces the demand upon the root.

3. Why isn’t this idea included as part of the standard multiple-granularity locking protocol for a centralized DBMS?