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Data Warehousing and Data Mining
notes
figure 10.2: comparison of product sales by city
Figure 10.2 compares the sales of various products in different cities for January 2001 (shown)
and February 2001 (not shown). This view of the data might be used to identify products that
are performing poorly in certain markets. Figure 10.3 shows sales of various products during a
four-month period in Rome (shown) and Tokyo (not shown). This view of the data is the basis
for trend analysis.
figure 10.3: comparison of product sales by Month
A cube shape is three dimensional. Of course, measures can have many more than three
dimensions, but three dimensions are the maximum number that can be represented pictorially.
Additional dimensions are pictured with additional cube shapes.
10.3 relational implementation of the Model
The relational implementation of the multi-dimensional data model is typically a star schema, as
shown in Figure 10.4, a snowflake schema or a fact constellation schema.
10.3.1 star schema
A star schema is a convention for organising the data into dimension tables, fact tables, and
materialised views. Ultimately, all of the data is stored in columns, and metadata is required to
identify the columns that function as multidimensional objects.
190 LoveLy professionaL university
