Creating Analysis Services Cubes - SQL Server Analysis Services 2012 Cube Development - page 74

13. You should notice on the Dimensions pane that the cube has four dimen-
sions even though we had advised the Cube Wizard to only include date and
promotion dimensions.
14. Recall from Chapter 2 , Defining Analysis Services Dimensions , that each di-
mension table could have one or multiple relationships with the fact table.
The FactResellerSales references date dimension's DateKey column
three times: OrderDateKey , DueDateKey , and ShipDateKey .
15. The Cube Wizard recognizes this and creates three separate cube dimen-
sions based on a single date dimension available in the database. Such
dimensions are called role playing dimensions. They can be very help-
ful—instead of storing data in three separate tables, corresponding to three
SSAS objects, you only have to store and process date-related data once.