Star Schema The Complete Reference

CHAPTER 12Factless Fact Tables

In a dimensional design, the fact table is the locus for process measurement. It is the place where measurements are stored. The measurements are called facts, which is where the fact table gets its name. Paradoxically, a fact table does not always require facts to measure a process.

A fact table that contains no facts is called a factless fact table. This oxymoron aptly describes the design technique discussed in this chapter. Although no facts are explicitly recorded in a factless fact table, it does support measurement. A factless fact table is useful in two kinds of situations:

• Factless fact tables for events record the occurrence of activities. Although no facts are stored explicitly, these events can be ...