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4.2 Data Warehouse Modeling: Data Cube and OLAP 149

OLAP and SDB systems, however, have distinguishing differences. While SDBs tend
to focus on socioeconomic applications, OLAP has been targeted for business appli-
cations. Privacy issues regarding concept hierarchies are a major concern for SDBs. For
example, given summarized socioeconomic data, it is controversial to allow users to view
the corresponding low-level data. Finally, unlike SDBs, OLAP systems are designed for
efficiently handling huge amounts of data.

4.2.6 A Starnet Query Model for Querying
Multidimensional Databases
The querying of multidimensional databases can be based on a starnet model, which
consists of radial lines emanating from a central point, where each line represents a
concept hierarchy for a dimension. Each abstraction level in the hierarchy is called a
footprint. These represent the granularities available for use by OLAP operations such
as drill-down and roll-up.

Example 4.5 Starnet. A starnet query model for the AllElectronics data warehouse is shown in
Figure 4.13. This starnet consists of four radial lines, representing concept hierarchies
for the dimensions location, customer, item, and time, respectively. Each line consists
of footprints representing abstraction levels of the dimension. For example, the time
line has four footprints: “day,” “month,” “quarter,” and “year.” A concept hierarchy may
involve a single attribute (e.g., date for the time hierarchy) or several attributes (e.g., the
concept hierarchy for location involves the attributes street, city, province or state, and
country). In order to examine the item sales at AllElectronics, users can roll up along the

location
customer
continent
group
country
province_or_state category
city name

street
item
day name brand category type
month
quarter
year

time

Figure 4.13 A starnet model of business queries.