Physical database design can be marked as a crucial step in the overall design process of databases. The outcome of physical database design is a physical schema which describes the storage and access structures of the stored database. The selection of an ecient physical schema is an NP-complete problem. A signi cant number of eorts has been reported to develop tools that assist in the selection of physical schemas. Most of the eorts implicitly apply a number of heuristics to avoid the evaluation of all schemas. In this paper, we present an approach, based on the Dempster-Shafer theory, that explicitly models a rich set of heuristics |used for the selection of an ecient physical schema | into knowledge rules. These rules may be loaded into a knowledge base, which, in turn, can be embedded in physical database design tools.
