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Relational Design and Redundancy

19 January, 2016 - 14:28

Generally, a good relational database design must capture all of the necessary attributes/associations and should do this with a minimal amount of stored information (it means there is no redundant data).

In database design, redundancy is generally a “bad thing” because it causes problems maintaining consistency after updates. However, it can sometimes lead to performance improvements e.g. may be able to avoid a join to collect bits of data together.

Consider the following table defining bank accounts/branches:

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Figure 10.1 Source: http://cnx.org/content/m28252/latest/