Data redundancy

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Data redundancy occurs in database systems which have a field that is repeated in two or more tables. For instance, 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[edit]

  1. ^ Jorge H. Doorn; Laura C. Rivero (2002). Database integrity: challenges and solutions. Idea Group Inc (IGI). pp. 4–5. ISBN 978-1-930708-38-9. Retrieved 23 January 2011. 
  2. ^ a b Peter Rob; Carlos Coronel (2009). Database systems: design, implementation, and management. 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. 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. For Dummies. pp. 126–127. ISBN 978-0-470-55741-9. Retrieved 1 February 2011. 

See also[edit]