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Dimension Table




The fact table contains Business Fact s or ''measures'' and Foreign Key s which refer to Candidate Key s (normally Primary Key s) in the dimension tables.

The dimension tables contain Attribute s or (fields) used to constrain and group Data when performing Data Warehousing Queries .

Over time, the attributes of a given row in a dimension table may change. For example, the shipping address for a company may change. Kimball refers to this phenomena as Slowly Changing Dimensions. Strategies for dealing with this kind of change are divided into three categories:

  • Type One - Simply overwrite the old value(s).

  • Type Two - Add a new row containing the new value(s), and distinguish between the rows using Tuple-versioning techniques.

  • Type Three - Add a new attribute to the existing row.



SEE ALSO



REFERENCES

  • Kimball, Ralph et al ( 1998 ); ''The Data Warehouse Lifecycle Toolkit'', p17. Pub. Wiley. ISBN 0-471-25547-5.


  • Kimball, Ralph ( 1996 ); ''The Data Warehouse Toolkit'', p100. Pub. Wiley. ISBN 0-471-15337-0.