Microsoft® SQL Server® 2008 Analysis Services Step by Step

Creating a Fact Dimension

A fact table may have columns that contain descriptive attributes. If the attributes have low cardinality—meaning that the values in the column are repeated and the number of distinct values is low compared to the number of fact records—you should create a dimension table and replace the attribute columns in the fact table with a column containing a dimension key. If the attributes have a high or even one-to-one cardinality—meaning a unique value for each fact table record—it is best to not create a dimension table. In this case, the attributes as a group are referred to as a degenerate dimension. You can create an Analysis Services dimension from the degenerate dimension attribute columns in a fact table.

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