Chapter 10, Problem 2P

Explanation of Solution

Concurrency control:

The purpose of concurrency control is to ensure the serializability of transaction in a multiuser database environment and it is the process of coordinating the simultaneous execution.

Common problems with concurrent transaction execution:

Concurrency transaction is one or more transactions are processed on same time. During the concurrency transaction execution the following problems can occur in the transaction. They are:

• Lost updates
• Uncommitted data
• Inconsistent retrievals

Lost updates:

A data can be lost when the two different transactions want to update same field or row within the database at the same time.

• For example: if the transactions “T1” and “T2” want to update the same element and one of the updates is lost or overwritten by other transactions.

Uncommitted data:

The data of the transactions are not committed when the transactions are executed concurrently...