Every dimension table has a single primary key column. This primary key is embedded as a foreign key in any associated fact table where the dimension row’s descriptive context is exactly correct for that fact table row. Dimension tables are usually wide, ﬂat denormalized tables with many low-cardinality text attributes. While operational codes and indicators can be treated as attributes, the most powerful dimension attributes are populated with verbose descriptions. Dimension table attributes are the primary target of constraints and grouping speciﬁcations from queries and BI applications. The descriptive labels on reports are typically dimension attribute domain values.