Professional SQL Server™ Analysis Services 2005 with MDX

5.7. Creating a Snowflake Dimension

A snowflake dimension is a dimension that is created using a set of dimension tables. A snowflake dimension normally suggests that the tables in the data source have been normalized. Normalization is the process by which tables of a relational database are designed to remove redundancy and are optimized for frequent updates. Most database design books, including The Data Warehouse Toolkit by Ralph Kimball (Wiley, 1996) and An Introduction to Database Systems by C. J. Date (Addison Wesley, 2003), talk about the normalization process in detail.

The columns from different tables of a snowflake dimension often result in levels of a hierarchy in the dimension. The best way to understand a snowflake dimension is to create one yourself. To create one we're going to need two additional tables added from the source to our DSV. Here is how to add the two tables:

1. Open the AdventureWorksDW DSV and click on the Add/Remove Tables icon (top left icon in the DSV).

2. Control-Click on "dbo.DimProductCategory" and "dbo.DimProductSubcategory" and click the right arrow > to move the two tables from the source to the DSV. Click OK to continue.

Now that you have the necessary tables, the following steps describe how to create a snowflake dimension called DimProducts from AdventureWorksDW.

1. Launch the Dimension Wizard, accept the defaults, and proceed through the pages of the Wizard to the "Select Main Dimension Table" screen. Select the dbo.DimProduct Table from the drop-down ...