Logical Data Warehouse Design - Data Warehouse Systems: Design and Implementation - page 155

snowflake schema. Therefore, both the star and the snowflake and schema
representation are supported in Analysis Services.
Balanced hierarchies are supported by Analysis Services. Examples
of these hierarchies in the Northwind cube are the Time and the Product
dimensions studied above.
Fig. 5.28 Browsing the Supervision hierarchy in the Employee dimension
Analysis Services does not support unbalanced hierarchies .Wehave
seen in Sect. 5.5.2 several solutions to cope with them. On the other hand,
Analysis Services supports parent-child hierarchies , which are a special
case of unbalanced hierarchies. We have seen that such hierarchies define a
hierarchical relationship between the members of a dimension. An example
is the Supervision hierarchy in the Employee dimension. As can be seen in
Fig. 5.21 , in the underlying dimension table, the column SupervisorKey is a
foreign key referencing EmployeeKey . When defining the dimension, the Usage
property for the attributes of the dimension determines how they will be used.
In our case, the value of such property will be Parent for the SupervisorKey
attribute, will be Regular for all other attributes except EmployeeKey ,and
will be Key for the attribute EmployeeKey . Figure 5.28 showsthemembersof
the Supervision hierarchy, where the named calculation FullName is displayed
when browsing the hierarchy.
In parent-child hierarchies, the hierarchical structure between members is
taken into account when measures are aggregated. Thus, for example, the
total sales amount of an employee would be her personal sales amount plus
the total sales amount of all employees under her in the organization. Each
member of a parent-child hierarchy has a system-generated child member that
contains the measure values directly associated with it, independently of its
descendants. These are referred to as data members .The MembersWithData
property of the parent attribute controls the visibility of data members: they
are shown when the property is set to NonLeafDataVisible , while they are