Oracle Corporation
Nested hierarchical rollups by level using a normalized table

Abstract:

Nested hierarchies can be efficiently analyzed by normalizing a portion of the hierarchy as defined by a limiting factor for the hierarchy. In a project hierarchy wherein each project contains a task hierarchy, each task hierarchy can be normalized. Further, the projects can be assigned to levels such that data for each level can be indexed, partitioned, or otherwise differentiated. The data then can be efficiently rolled up by level using the partially normalized hierarchy.