Data redundancy

Source: Wikipedia, the free encyclopedia.

In computer

computer buses, data redundancy is the existence of data that is additional to the actual data and permits correction of errors in stored or transmitted data. The additional data can simply be a complete copy of the actual data (a type of repetition code), or only select pieces of data that allow detection of errors and reconstruction
of lost or damaged data up to a certain level.

For example, by including computed check bits,

file systems such as Btrfs and ZFS use data and metadata checksumming in combination with copies of stored data to detect silent data corruption and repair its effects.[3]

In database systems

While different in nature, data redundancy also occurs in

database denormalization
; used to improve performance of database queries (shorten the database response time).

For instance, when customer data are duplicated and attached with each product bought, then redundancy of data is a known source of inconsistency since a given customer might appear with different values for one or more of their attributes.[4] Data redundancy leads to data anomalies and corruption and generally should be avoided by design;[5] applying database normalization prevents redundancy and makes the best possible usage of storage.[6]

See also

References

  1. ^ Xin Li; Michael C. Huang; Kai Shen; Lingkun Chu (9 May 2010). "A Realistic Evaluation of Memory Hardware Errors and Software System Susceptibility" (PDF). cs.rochester.edu. Retrieved 16 January 2015.
  2. ^ Remzi H. Arpaci-Dusseau; Andrea C. Arpaci-Dusseau (3 January 2015). "Operating Systems – Three Easy Pieces: Redundant Arrays of Inexpensive Disks (RAIDs)" (PDF). cs.wisc.edu. Retrieved 16 January 2015.
  3. ^ Margaret Bierman; Lenz Grimmer (August 2012). "How I Use the Advanced Capabilities of Btrfs". Oracle Corporation. Retrieved 26 January 2015.
  4. ISBN 978-1-930708-38-9
    . Retrieved 23 January 2011.
  5. ISBN 978-1-4239-0201-0
    . Retrieved 22 January 2011.
  6. ISBN 978-81-7758-118-8
    . Retrieved 4 February 2011.
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