Chapter 1, Problem 1RQ

To determine

Definition of redundancy and problems that can occur due to redundancy.

Explanation of Solution

Redundancy refers to repeated occurrence of same data values at multiple places. For example, consider the student table below:

StudentID	StudentName	Age	Address	Subjects	Marks
101	John Arry	27	Park Street	Physics	80
101	John Arry	27	Park Street	Chemistry	70
101	John Arry	27	Park Street	Mathematics	100
104	Paul Smith	28	Avenue Street	Chemistry	85
104	Paul Smith	28	Avenue Street	Physics	90
106	Massie Williams	26		Mathematics	56

The above table consists of redundant data for columns StudentName, StudentID, Age and Address.

This redundancy can result in many problems. Redundancy can result in inconsistencies in data and result in misleading information which can later affect the decision making.

Also, due to redundancy, it becomes very hard to make correction or updation in data. For example, considering the above table, suppose in case the student name for studentID 101 was misread and entered incorrectly. Now, in order to update the correct name it will be time consuming and a cumbersome process since correction needs to be performed at multiple places.

Redundancy also results in eating up extra storage spaces and causes storage files to become heavy. Due to which it becomes time consuming to transfer files or retrieve information from it. Thus, it results in an inefficient system performance.