Degenrated Dimension

A degenerate dimension (DD) acts as a dimension key in the fact table, however does not join to acorresponding dimension table because all its interesting attributes have already been placed in other analytic dimensions. Sometimes people want to refer to degenerate dimensions as textual facts, however they're not facts since the fact table's primary key often consists of the DD combined with one or more additional dimension foreign keys.Degenerate dimensions commonly occur when the fact table's grain is a single transaction (or transaction line). Transaction control header numbers assigned by the operational business process are typically degenerate dimensions, such as order, ticket, credit card transaction, or check numbers. These degenerate dimensions are natural keys of the "parents" of the line items. Even though there is no corresponding dimension table of attributes, degenerate dimensions can be quite useful for grouping together related fact tables rows