Professional Microsoft® SQL Server® Analysis Services 2008 with MDX

1.3. Inmon Versus Kimball — Different Approaches

In data warehousing there are two commonly acknowledged approaches to building a decision support infrastructure, and both can be implemented using the tools available in SQL Server Analysis Services (SSAS) 2008. It is worth understanding these two approaches and the often-cited difference of views that result. These views are expressed most overtly in two seminal works: The Data Warehouse Lifecycle Toolkit by Ralph Kimball, Laura Reeves, Margy Ross, and Warren Thornthwaite, and Corporate Information Factory by Bill Inmon, Claudia Imhoff, and Ryan Sousa.

Kimball identified early on the problem of the stovepipe. A stovepipe is what you get when several independent systems in the enterprise go about identifying and storing data in different ways. Trying to connect these systems or use their data in a warehouse results in something resembling a Rube-Goldberg device. To address this problem, Kimball advocates the use of conformed dimensions. Conformed refers to the idea that dimensions of interest — sales, for example — should have the same attributes and rollups (covered in the "Cubes" section earlier in this chapter) in one data mart as another. Or at least one should be a subset of the other. In this way, a warehouse can be formed from data marts. The real gist of Kimball's approach is that the data warehouse contains dimensional databases for ease of analysis and that the user queries the warehouse directly.

The Inmon approach has ...