Balanced and Unbalanced Hierarchies
In a balanced hierarchy, all branches of the hierarchy descend to the same level, and each member's logical parent is the level immediately above the member. In the preceding Geography dimension example, if the country members are limited to France and Germany, the dimension's hierarchy is balanced. All branches of the hierarchy terminate at cities at the City level. The parent of each city is either France or Germany, and Europe is the parent of both France and Germany.
In an unbalanced hierarchy, branches of the hierarchy descend to different levels. For example, an Organization dimension contains a member for each employee in a company. The CEO is the top member in the hierarchy, and the division managers and executive secretary are immediately beneath the CEO. The division managers have subordinate members but the executive secretary does not.
In Analysis Services, balanced hierarchies are supported in regular and virtual dimensions. Unbalanced hierarchies are supported only in parent-child dimensions.
It may be impossible for end users to distinguish between unbalanced and ragged hierarchies. However, you can employ different techniques and properties to support these two types of hierarchies.