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Avoid Inconsistency


In case of a file-system... since the files and application programs are created by different programmers (or users) over a longer period of time, the records in the files are likely to have different values i.e., various copies of same data may no longer agree.

As an example, consider the example mentioned in centralized control page. In this case, the change in emp-name of an employee might have taken place in HumanResources and not in Administration department. This leads to two different names for the same employee in two different departments...causing inconsistency.

The disadvantages of uncontrolled redundancy are
- avoids inconsistency
- a nonredundant database will always be consistent
- controlling redundandy (i.e., ensuring that, any change made to a field, changes all other copies of that field) guarantees removal of inconsistency in the database, as seen by the user.

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