Chapter 18, Problem 7PE

a.

Explanation of Solution

Serializabiltiy

• If two transactions have an I mode lock on the same item, then serializibilty can be shown.
• Just like read operations, i...

b.

Explanation of Solution

Inclusion of increment modes

• The increment lock mode being compatible allows multiple incrementing transactions to take the lock simultaneously.
• Thus it improves the concurrency of the protocol.
• In the absence of increment mode, an exclusive mode will have to be taken on a data item by each transaction that wants to increment the value of the data item...