Pre-Aggregation for Irregular OLAP Hierarchies with the TreeScape System

We present the TreeScape system which, unlike any other system known to the authors, enables the reuse of pre-computed aggregate query results involving the kinds of irregular dimension hierarchies that occur frequently in practice. The system establishes a foundation for obtaining high-performance query processing while precomputing only few aggregates. It is demonstrated how this reuse of aggregates is enabled through dimension transformations that occur transparently to the user.