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Chapter 3
Exclusive Attributes and Defining Characteristics
Dimensions with
mixed types often
contain mutually
exclusive attributes
As you explore missing and mandatory examples you may come across mutually
exclusive attributes: attribute pairs or attribute groups that cannot both have values
for the same member. Figure 3-5 shows examples of exclusive customer attributes.
Customers can have a DATE OF BIRTH and GENDER or a SIC CODE and
EMPLOYEE COUNT but not all 4 values. This is often an indication that you have
discovered a heterogeneous dimension, one that contains a highly diverse set of
members that are described in different ways (even if they are measured in similar
ways by taking part in similar business events). In this case, the customer dimen-
sion contains businesses and consumers. Their mutually incompatible descriptions
should be marked as exclusive attributes using the short code Xn where n is an
exclusive group number. In Figure 3-5, consumer attributes are exclusive group 1,
marked X1, and business attributes are group 2, marked X2. Exclusive attributes
are often a sign of mixed business models; e.g., business-to-business (B2B) and
business-to-consumer (B2C), offering products and services.
Figure 3-5
Exclusive customer
attributes
Exclusive attributes
have at least one
defining
characteristic
If you discover exclusive attributes, you need to find their defining characteristic(s):
one or more attributes whose values control the validity/applicability of the exclu-
sive attributes. For customer there is a single attribute, CUSTOMER TYPE, which
dictates whether the attributes in X1 or X2 are valid. This is marked as a defining
characteristic with the code DC. If a dimension contains multiple defining
characteristics each DC code should be followed by a list of the exclusive group
numbers controlled by the attribute. For example, if CUSTOMER TYPE was one
of several DC attributes in CUSTOMER it would be marked DC1,2 because it
selects between X1 and X2 group attributes only.
DCn,n : Defining Characteristic, dictates which exclusive attributes are valid.
Xn
: Exclusive attribute or attribute group