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'''Data redundancy''' occurs in [[Relational database management system|database systems]] which have a field that is repeated in two or more [[Table (information)|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.<ref name="DoornRivero2002">{{cite book|author1=Jorge H. Doorn|author2=Laura C. Rivero|title=Database integrity: challenges and solutions|url=http://books.google.com/books?id=fJWncL6mjnwC&pg=PA4|accessdate=23 January 2011|year=2002|publisher=Idea Group Inc (IGI)|isbn=9781930708389|pages=4–5}}</ref> Data redundancy leads to [[Data corruption|data anomalies and corruption]] and generally should be avoided by design.<ref name="RobCoronel2009">{{cite book|author1=Peter Rob|author2=Carlos Coronel|title=Database systems: design, implementation, and management|url=http://books.google.com/books?id=gCzfjlWOVAAC&pg=PA88|accessdate=22 January 2011|year=2009|publisher=Cengage Learning|isbn=9781423902010|page=88}}</ref> [[Database normalization]] prevents redundancy and makes the best possible usage of [[Computer data storage|storage]].<ref name="LimitedItl2009">{{cite book|author1=I. T. L. Education Solutions Limited|author2=Itl|title=Introduction to Information Technology|url=http://books.google.com/books?id=ib2MI6_B9qYC&pg=PA522|accessdate=4 February 2011|year=2009|publisher=Pearson Education India|isbn=9788177581188|page=522}}</ref> Proper use of [[foreign key]]s can minimize data redundancy and chance of destructive anomalies.<ref name="RobCoronel2009"/> However sometimes concerns of efficiency and convenience can result redundant data design despite the risk of corrupting the data.<ref name="Taylor2010">{{cite book|author=Allen G. Taylor|title=SQL for Dummies|url=http://books.google.com/books?id=r4s1QTHpQosC&pg=PA126|accessdate=1 February 2011|date=2 February 2010|publisher=For Dummies|isbn=9780470557419|pages=126–127}}</ref>
'''Data redundancy''' occurs in [[Relational database management system|database systems]] which have a field that is repeated in two or more [[Table (information)|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.<ref name="DoornRivero2002">{{cite book|author1=Jorge H. Doorn|author2=Laura C. Rivero|title=Database integrity: challenges and solutions|url=http://books.google.com/books?id=fJWncL6mjnwC&pg=PA4|accessdate=23 January 2011|year=2002|publisher=Idea Group Inc (IGI)|isbn=9781930708389|pages=4–5}}</ref> Data redundancy leads to [[Data corruption|data anomalies and corruption]] and generally should be avoided by design.<ref name="RobCoronel2009">{{cite book|author1=Peter Rob|author2=Carlos Coronel|title=Database systems: design, implementation, and management|url=http://books.google.com/books?id=gCzfjlWOVAAC&pg=PA88|accessdate=22 January 2011|year=2009|publisher=Cengage Learning|isbn=9781423902010|page=88}}</ref> [[Database normalization]] prevents redundancy and makes the best possible usage of [[Computer data storage|storage]].<ref name="LimitedItl2009">{{cite book|author1=I. T. L. Education Solutions Limited|author2=Itl|title=Introduction to Information Technology|url=http://books.google.com/books?id=ib2MI6_B9qYC&pg=PA522|accessdate=4 February 2011|year=2009|publisher=Pearson Education India|isbn=9788177581188|page=522}}</ref> Proper use of [[foreign key]]s can minimize data redundancy and chance of destructive anomalies.<ref name="RobCoronel2009"/> However, concerns of efficiency and convenience can sometimes result in redundant data design despite the risk of corrupting the data.<ref name="Taylor2010">{{cite book|author=Allen G. Taylor|title=SQL for Dummies|url=http://books.google.com/books?id=r4s1QTHpQosC&pg=PA126|accessdate=1 February 2011|date=2 February 2010|publisher=For Dummies|isbn=9780470557419|pages=126–127}}</ref>


==Notes and references==
==Notes and references==

Revision as of 13:20, 26 April 2012

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, concerns of efficiency and convenience can sometimes result in 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. Retrieved 23 January 2011.
  2. ^ a b Peter Rob; Carlos Coronel (2009). Database systems: design, implementation, and management. Cengage Learning. p. 88. ISBN 9781423902010. Retrieved 22 January 2011.
  3. ^ I. T. L. Education Solutions Limited; Itl (2009). Introduction to Information Technology. Pearson Education India. p. 522. ISBN 9788177581188. Retrieved 4 February 2011.
  4. ^ Allen G. Taylor (2 February 2010). SQL for Dummies. For Dummies. pp. 126–127. ISBN 9780470557419. Retrieved 1 February 2011.

See also


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