15.00 - Unbalanced Hierarchies and Unnormalized Physical Schemas - Teradata Database

Teradata Database Design

Teradata Database
User Guide

Unbalanced Hierarchies and Unnormalized Physical Schemas

You cannot make the universal assumption that all levels in a dimensional model are balanced. A star schema dimension table, which requires fixed columns for each level, has considerable difficulty in handling unbalanced hierarchies.

An unbalanced hierarchy, as shown in the following figure, is a hierarchy in which a particular level can have its parent at different levels above it. An account executive, for example, might report to a region or a subregion.

Because a star schema creates specific columns to handle each level in a hierarchy, it requires that all hierarchies be balanced so that, using the current example, an account executive would always need to be at level three.