7/11/2014 Data redundancy - Wikipedia, the free encyclopedia

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Data redundancyFrom Wikipedia, the free encyclopedia

Data redundancy occurs in database systems which have a field that is repeated in two or more tables. Forinstance, when customer data are duplicated and attached with each product bought, then redundancy of data is a

known source of inconsistency since customer might appear with different values for given attribute.[1] Data

redundancy leads to data anomalies and corruption and generally should be avoided by design.[2] Database

normalization prevents redundancy and makes the best possible usage of storage.[3] Proper use of foreign keys can

minimize data redundancy and chance of destructive anomalies.[2] However, concerns of efficiency and

convenience can sometimes result in redundant data design despite the risk of corrupting the data.[4]

Notes and references

See also

Data maintenance

Data deduplication

Error detection and correction

RAID (redundant array of independent disks)

Redundancy (engineering)

Redundancy (information theory)

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Categories: Database management systems Data Data modeling Databases Database stubs

1. ^ Jorge H. Doorn; Laura C. Rivero (2002). Database integrity: challenges and solutions

(http://books.google.com/books?id=fJWncL6mjnwC&pg=PA4). Idea Group Inc (IGI). pp. 45. ISBN 978-1-

930708-38-9. Retrieved 23 January 2011.

2. ^a b Peter Rob; Carlos Coronel (2009). Database systems: design, implementation, and management

(http://books.google.com/books?id=gCzfjlWOVAAC&pg=PA88). Cengage Learning. p. 88. ISBN 978-1-4239-

0201-0. Retrieved 22 January 2011.

3. ^ I. T. L. Education Solutions Limited; Itl (2009). Introduction to Information Technology

(http://books.google.com/books?id=ib2MI6_B9qYC&pg=PA522). Pearson Education India. p. 522. ISBN 978-81-

7758-118-8. Retrieved 4 February 2011.

4. ^ Allen G. Taylor (2 February 2010). SQL for Dummies (http://books.google.com/books?

id=r4s1QTHpQosC&pg=PA126). For Dummies. pp. 126127. ISBN 978-0-470-55741-9. Retrieved 1 February

2011.

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