Loading fact tables
Fact tables contain the central information of star models. In this section, you will learn to load these kinds of tables. This is the list of topics covered:
- Introducing different kinds of fact tables
- Translating business keys into surrogate keys
- Loading fact tables with PDI
Learning the basics about fact tables
As explained in the introduction, fact tables are the central tables in a dimensional model. While the dimensions serve to group, filter, and describe data, the fact tables contain the measures of the business. There are basically two types of fact tables:
- Cumulative: They describe what happened over a period of time—a
Sales
fact table is a typical example of this. The measures for these types of fact tables are mostly additive, that is, measures that can be added across all dimensions. - Snapshots: They describe the activity of a business process, with pictures taken at a given instant of time. Examples of this kind of fact table are postal tracking systems, order processing...