Database Reference
In-Depth Information
In Figure
12-36
you can see that after our new cube was created, the Categories dimension was not
automatically added to the cube. The Cube Wizard does not automatically create a reference dimension for you,
as it does with role-playing and parent-child dimensions. The Cube Wizard identifies which dimension will be
part of a cube based on direct connections from a dimension table to a fact table in a data source view. Because
the DimCategories table and the FactOrders table do not have a direct connection, the wizard assumes that they
are not related (Figure
12-27
). This means that you must manually add a reference dimension to an existing cube,
without the help of the Cube Wizard.
You can add it yourself by right-clicking in the Dimensions pane and choosing the Add Cube Dimension
option from the context menu.
Figure 12-36.
Adding a new dimension to an existing cube
Once the dimension has been added to the cube, access the Dimension Usage tab to complete its
configuration. Unlike the parent-child and role-playing dimensions, a reference dimension is defined as a
reference relationship. To configure this, click the ellipsis (. . .) as circled in Figure
12-37
to access the Dened
Relationship dialog window. Then use the Select Relationship type dropdown box and configure it to use the
Referenced
option, as indicated in Figure
12-37
.
You also have to identify which table is used as the intermediate dimension. In our example, the
intermediate dimension table is DimProducts.
The image shown on the left of the dialog window is useful to understand how the relationship exists from
the perspective of the cube. Notice how the dotted line represents the logical relationship between the fact table
and the dimension table and how the solid line represents the relationships as defined in the data source view.
