The Data Warehouse Development Life Cycle
Oracle Data Warehouse DesignHandling Attribute Classification
One of the foremost problems in a data warehouse is the design of
the non-fact data attributes. In all cases, attributes will either
be choose-one, finite value, or hierarchical. Let’s discuss each of
these data attributes and the design techniques that can be used to
implement them within a data warehouse.
* Choose-one Attributes--This would be the case with mutually
exclusive attributes such as sex, level of education, category of
income, and so on. In most cases, a flag column would be used to
represent these data attributes, and Oracle check constraints would
be used to enforce the valid values for the flag. The check
constraint validates incoming columns at row insert time. For
example, rather than having an application verify that all
occurrences of region are North, South, East, or West, a check
constraint can be added to the table definition to ensure the
validity of the region column.
* Finite Value Attributes--These attributes contain specific
values that cannot be categorized by range values. Examples include
last_name, street_address, and phone_number.
* Hierarchical Attributes--This is the most challenging to
represent in a data warehouse. Within a classification tree, each
branch may have many levels, and once an entity has been classified,
it should automatically participate in all superclasses up the tree.
This is an excerpt from "High Performance