Chapter 12. Subset Dimensions

Some users never need the most detailed data. For example, rather than requiring dates, it is more likely they want records for a certain month. Rather than the national sales data, they may be more interested in the data for a certain state. These special dimensions contain selected rows from the detailed dimensions, hence the name subset dimensions. Since subset dimensions are smaller than detailed dimensions, they are easier to use and provide faster query response.

In this chapter, you will prepare two special dimensions that you derive from existing dimensions: the month roll-up dimension (a subset of the date dimension) and the Pennsylvania state customer dimension (a subset of the customer dimension).