The Kimball Group Reader

Chapter 10More Dimension Patterns and Considerations

So you thought you knew everything you needed to know about dimension tables after reading Chapter 9. Not so fast! There is much more where Chapter 9 leaves off.

We begin this chapter by discussing snowflaked versus outrigger dimension tables, plus bridge tables for handling both multi-valued dimension attributes as well as variable-depth hierarchical relationships. From there, we turn our attention to several patterns often observed with customer-centric dimension tables. We also describe approaches for handling the challenges presented by the internationalization of dimensional models.

The final section of this chapter provides a series of case studies from a variety of industries and application areas—insurance, voyage, human resources, finance, electronic commerce, text searching, and retail. Even if you don't work in one of these arenas, we encourage you to peruse these articles because the patterns and recommendations transcend industry or application boundaries.

Snowflakes, Outriggers, and Bridges

We begin by exploring the distinctions between snowflaked, outrigger, and bridge tables in dimensional modeling. In this section, bridge tables are described as a technique for modeling multi-valued dimension attributes; in the next section, we look at bridges to address variable-depth ragged hierarchies.

Several articles in this section originally referred to bridge tables as helper tables; the original references have been ...