Chapter 15. Dimension Hierarchies

Most dimensions have one or more hierarchies. For instance, the date dimension has one hierarchy with four levels: the year level, the quarter level, the month level, and the date level. These levels are represented by columns in the date_dim table. The date dimension has one-path hierarchy as it does not have any other hierarchy than the year-quarter-month-date path. In this chapter you learn about single-path hierarchies. In addition, this chapter talks about grouping and drilling queries on dimensions with hierarchies.