A Tree Comparison Approach to Detect Changes in Data Warehouse Structures

We present a technique for discovering and representing changes between versions of data warehouse structures. We select a tree comparison algorithm, adapt it for the particularities of multidimensional data structures and extend it with a module for detection of node renamings. The result of these algorithms are so called edit scripts consisting of transformation operations which, when executed in sequence, transform the earlier version to the later, and thus show the relationships between the elements of different versions of data warehouse structures. This procedure helps data warehouse administrators to register changes. We describe a prototypical implementation of the concept which imports multidimensional structures from Hyperion Essbase data warehouses, compares these versions and generates a list of differences.