My first Publication Agile-Data-Warehouse-Design-eBook | Page 80

3
M ODELING B USINESS D IMENSIONS
I keep six honest serving-men (They taught me all I knew);
Their names are What and Why and When And How and Where and Who.
— Rudyard Kipling, The Elephant’s Child
Business events and their numeric measurements are only part of the agile dimen-
sional modeling story. On their own, BEAM ✲ event tables are not sufficient to
design a data warehouse or even a data mart, because they do not contain all the
descriptive attributes required for reporting purposes. For complete BI flexibility,
stakeholders need both the atomic-level event details modeled so far and higher-
level descriptions that allow those details to be analyzed in practical ways. The data
structures that provide these descriptive attributes are dimensions. Business events
In addition to the 7Ws and example data tables, BEAM ✲ uses hierarchy charts and
change stories to discover and define dimensional attributes. Hierarchy charts are
used to explore the hierarchical relationships between attributes that support BI
drill-down analysis, while change stories allow stakeholders to describe their
business rules for handling slowly changing dimensions. BEAM✲ modelers
In this chapter we describe how these BEAM ✲ tools and techniques are used to
model complete dimension definitions from individual event details. We will use
the CUSTOMER and PRODUCT event story details from Chapter 2 for our
example dimension modelstorming with stakeholders. This chapter shows
Modeling the dimensions of a business event
Using the 7Ws and BEAM✲ tables to define dimensional attributes
need dimensions to
fully describe them
for reporting
purposes
draw hierarchy
charts and tell
change stories to
define dimensions
you how to model
dimensions from
event story details
Chapter 3 Topics
At a Glance
Drawing hierarchy charts to model dimensional hierarchies
Telling change stories to describe dimensional history
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