Logical Data Warehouse Design - Data Warehouse Systems: Design and Implementation - page 156

hidden when it is set to NonLeafDataHidden . We can see in Fig. 5.28 that the
data members are visible since both Andrew Fuller and Steven Buchanan
appear twice in the hierarchy. The MembersWithDataCaption property of the
parent attribute can be used to define a naming template for generating
names of data members.
Analysis Services does not support generalized hierarchies .Ifthe
members differ in attributes and in hierarchy structure, the common solution
is to define one hierarchy for the common levels and another hierarchy for
each of the exclusive paths containing the specific levels. This is the case for
most of the OLAP tools in the market. On the other hand, Analysis Services
supports the particular case of ragged hierarchies .Aswehavealready
seen, in a ragged hierarchy, the parent of a member may be in a level which
is not immediately above it. In a table corresponding to a ragged hierarchy,
the missing members can be represented in various ways: with null values or
empty strings or they can contain the same value as their parent.
In Analysis Services, a ragged hierarchy is defined using all of its levels,
that is, the longest path. To support the display of ragged hierarchies, the
HideMemberIf property of a level allows missing members to be hidden.
The possible values for this property and their associated behaviors are as
follows:

￿ Never : Level members are never hidden.
￿ OnlyChildWithNoName : A level member is hidden when it is the only child
of its parent and its name is null or an empty string.
￿ OnlyChildWithParentName : A level member is hidden when it is the only
child of its parent and its name is the same as the name of its parent.
￿ NoName : A level member is hidden when its name is empty.
￿ ParentName : A level member is hidden when its name is identical to that
of its parent.

In order to display ragged hierarchies correctly, the MDX Compatibility
property in the connection string from a client application must be set to 2.
If it is set to 1, a placeholder member is exposed in a ragged hierarchy.
With respect to alternative hierarchies , in Analysis Services, several
hierarchies can be defined on a dimension, and they can share levels.
For example, the alternative hierarchy in Fig. 4.9 will be represented by
two distinct hierarchies: the first one composed of Time → Month →

CalendarQuarter → CalendarYear and another one composed of Time → Month

→ FiscalYear .

Analysis Services supports parallel hierarchies , whether dependent or
independent. Levels can be shared among the various component hierarchies.
Finally, to represent nonstrict hierarchies in Analysis Services, it
is necessary to represent the corresponding bridge table as a fact table,
as it was explained in Sect. 5.9.3 . In the relational representation of the

FiscalQuarter →