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Sunday, 22 January 2017
What is data redundancy
Data redundancy is a problem that causes storing of redundant (excess) amount of data. Here, the redundancy means unnecessary duplication of data. The data may be duplicated in either of the following ways;
The data those are stored in excess copies as whole. That is, storage of same data in multiple same copies. For example, storing customer data in two different computers.
The data those are partially unnecessarily duplicated. That is, we store part of some data in multiple locations/copies. For example, employee mobile number is stored in employee personal data, employee department data, employee salary data, etc.
Data redundancy causes inconsistency. For example, if at all you need to change the mobile number of a particular employee, then you have to change in three locations as per the above example. If you miss any one location/copy then we are not sure about the mobile number.
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