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. Data redundancy leads to data anomalies and corruption and generally should be avoided by design. Database normalization prevents redundancy and makes the best possible usage of storage. Proper use of foreign keys can minimize data redundancy and chance of destructive anomalies. However, concerns of efficiency and convenience can sometimes result in redundant data design despite the risk of corrupting the data.
Notes and references
- 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.
- 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.
- 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.
- Allen G. Taylor (2 February 2010). SQL for Dummies. For Dummies. pp. 126–127. ISBN 978-0-470-55741-9. Retrieved 1 February 2011.
- Data maintenance
- Data deduplication
- Error detection and correction
- RAID (redundant array of independent disks)
- Redundancy (engineering)
- Redundancy (information theory)
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