GeoBI Architecture Based on Free Software: Experience and Review - Geographical Information Systems: Trends and Technologies - page 261

<Schema>
<Cube name="Demographics">
<Table name="DemographicsFactTable"/>
<Dimension name="CRDivision" foreignKey="DistrictFK">
<Hierarchy hasAll="false" primaryKey="DistrictID" primaryKeyTable = “District>
<Join leftKey=”CantonFK” rightAlias=”Canton” rightKey = “CantonPK”>
<Table name="District"/>
<Join leftKey=”ProvinceFK” rightKey = “ProvincePK”>
<Table name=”County”/>
<Table name=”Province”/>
</Join>
</Join>
<!—Level declarations -->
</Hierarchy>
<!—Other declarations follow -->
Fig. 9. Defi nition of a hierarchy based on normalized tables.
More advanced features
(Geo)Mondrian also includes other more advanced features, e.g., shared
dimensions, calculated members, virtual cubes, parent-child hierarchies,
and table aggregations. Some of them were required in our project.
Shared dimensions. A cube defi nition can be simplifi ed by reusing already
existing defi nitions for those dimensions, whether they are conventional or
spatial, that are shared among different cubes. In our example, we shared
the CRDivision dimension as defi ned in Fig. 7 between the Demographics
and Cancer cubes. As can be seen in Fig. 10, the CRDivision dimension with
its hierarchies is defi ned only once in the schema outside of any other cube
defi nitions. Then, each cube that requires the inclusion of this dimension
uses the label DimensionUsage (instead of the label Dimension ) indicating as
a source the dimension globally defi ned for this schema.
<Schema>
<Dimension name="CRDivision” >
<!-- Dimension definition as presented in Fig. 7. -->
</Dimension>
<Cube name="Demographics">
<Table name="DemographicsFactTable"/>
<DimensionUsage name="CRDivision" source="CRDivision" foreignKey="DistrictFK"/>
<!-- Definition of other specific for the cube dimensions and measures -->
</Cube>
<Cube name="Cancer">
<Table name="CancerFactTable"/>
<DimensionUsage name="CRDivision" source="CRDivision" foreignKey="DistrictFK"/>
<!-- Definition of other specific for the cube dimensions and measures -->
</Cube>
</Schema>
Fig. 10. A shared District dimension between the Demographics and Cancer cubes.