A strategy for reducing the effort for database schema maintenance

In a typical database design a conceptual schema which specifies the requirements about the database is first built. Then it is transformed, either in a single or in a multiple step, into a schema which is in a form suitable for the chosen database management system. When requirements change the conceptual schema must be updated and the modifications must be propagated down to the DBMS schema, with possibly, a replaying of most processes that were carried out when the system was built. In order to minimize the effort required to propagate these changes methods based on the reuse of the pre- vious design documentation are often advised. These methods are generally only roughly specified. This par- tially reduces the advantages of reuse since it demands for important choices that require a deep understanding of the whole database design process. This paper shows how this problem can be overcome in a framework in which the schema design is carried out through precisely dened schema transformations.