Data redundancy

Data redundancy occurs in database systems which have a field that is repeated in two or more tables. For instance, in case when customer data is 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 sometimes concerns of efficiency and convenience can result redundant data design despite the risk of corrupting the data.[4]

Notes and references

  1. ^ Jorge H. Doorn; Laura C. Rivero (2002). Database integrity: challenges and solutions. Idea Group Inc (IGI). pp. 4–5. ISBN 9781930708389. http://books.google.com/books?id=fJWncL6mjnwC&pg=PA4. Retrieved 23 January 2011. 
  2. ^ a b Peter Rob; Carlos Coronel (2009). Database systems: design, implementation, and management. Cengage Learning. p. 88. ISBN 9781423902010. http://books.google.com/books?id=gCzfjlWOVAAC&pg=PA88. Retrieved 22 January 2011. 
  3. ^ I. T. L. Education Solutions Limited; Itl (2009). Introduction to Information Technology. Pearson Education India. p. 522. ISBN 9788177581188. http://books.google.com/books?id=ib2MI6_B9qYC&pg=PA522. Retrieved 4 February 2011. 
  4. ^ Allen G. Taylor (2 February 2010). SQL for Dummies. For Dummies. pp. 126–127. ISBN 9780470557419. http://books.google.com/books?id=r4s1QTHpQosC&pg=PA126. Retrieved 1 February 2011. 

See also

Concepts
Objects
Components
Functions