Using Domain-Derived Constraints

Accurately estimating the cardinality of aggregate views is crucial for logical and physical design of data warehouses. While the warehouse is under development and data are not available yet, the approaches based on accessing data cannot be adopted. This paper reports on the progress of an ongoing research aimed at devising a comprehensive approach to estimate the cardinality of views based on a-priori information derived from the application domain. The results we present concern the computation of upper and lower bounds for the cardinality of a view considering the functional dependencies between attributes of the multidimensional scheme and a set of cardinality constraints expressed on some other views. We propose a bounding strategy which achieves an e ective trade-o between the tightness of the bounds produced and the computational complexity, and outline a branch-and-bound approach to compute it. Finally, we discuss some open issues and sketch our future research.