Database Reference
In-Depth Information
Continent
Europe
Country
Belgium
Germany
Vatican
...
Region
Wallonie
...
State
Hainaut
Liège
...
Bayern
Sachsen
...
City
Chimay
Liège
Munich
Lepizig
Vatican
Fig. 4.8 Examples of instances of the ragged hierarchy in Fig. 4.2
An example is given in Fig. 4.9 a, where the Time dimension includes two
hierarchies corresponding to different groupings of months into calendar years
and fiscal years. Figure 4.9 b shows an instance of the dimension (we do not
show members of the Time level), where it is supposed that fiscal years begin
in February. As it can be seen, the hierarchies form a graph, since a child
member is associated with more than one parent member and these parent
members belong to different levels. Alternative hierarchies are needed when
we want to analyze measures from a unique perspective (e.g., time) using
alternative aggregations.
Note the difference between generalized and alternative hierarchies (see
Figs. 4.6 and 4.9 ). Although the two kinds of hierarchies share some levels,
they represent different situations. In a generalized hierarchy, a child member
is related to only one of the paths, whereas in an alternative hierarchy, a
child member is related to all paths , and the user must choose one of them
for analysis.
4.2.5 Parallel Hierarchies
Parallel hierarchies arise when a dimension has several hierarchies associ-
ated with it, accounting for different analysis criteria. Further, the component
hierarchies may be of different kinds.
Parallel hierarchies can be dependent or independent depending on
whether the component hierarchies share levels. Figure 4.10 shows an
example of a dimension that has two parallel independent hierarchies.
The hierarchy ProductGroups is used for grouping products according to
categories or departments, while the hierarchy DistributorLocation groups
them according to distributors' divisions or regions. On the other hand, the
Search WWH ::




Custom Search