Degenerate Dimension

by Amol 19. February 2011 11:12


Degenerate Dimension:

Degenerate Dimension is a dimension which is derived from the fact table and doesn't have its own dimension table.

Degenerate Dimension can be described in other words as

  • A degenerate dimension is data that is dimensional in nature but stored in a fact table.
  • Any Dimension keys that are not joined to dimension table are considered as degenerate dimension.
  • Degeneratate dimension when dimension keys are part fact table without having dimension.

For examle :

Order Number, Receipt Number, Bill Number are the degenerate dimension as they are part of trasaction fact table without having dimension attached to it.


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Types of Data Warehouse Dimension

by Amol 18. February 2011 08:51

In a data warehouse, dimension is one of the perspectives that can be used to analyze the data in an OLAP cube.
When you are browsing the data in a cube, you can view the data from the perspective of different combinations of dimensions.

With dimension, data can be slice and dice to analyse it in different prospective. Dimensions are used to provide structured lebeling information to measures. Another use of dimension other than lebeling is to provide filtering, grouping.

For example, for a Sales database, the dimensions could include Product, Time, Store, and Promotion.

Each dimension may have one or more hierarchies applied to it. For the "Date" dimension, there are several possible hierarchies: "Day > Month > Year", "Day > Week > Year", "Day > Month > Quarter > Year", etc.

Types of dimension :

  1. Conformed dimension
  2. Junk dimension
  3. Degenerate dimension
  4. Role-playing dimensions


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Data Warehouse

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