Meta object management and its application to database evolution

Abstract In this paper we address the problem of supporting more exibility on the schema of objectoriented databases We describe a general framework based on an objectoriented data model where three levels of objects are distinguished data objects schema objects andmeta schema objects We discuss the prerequisites for applying the query and update operations of an object algebra uniformly on all three levels As a sample application of the framework we focus on database evolution that is realizing incremental changes to the database schema and their propagation to data instances We show how each schema update of a given taxonomy is realized by direct updating of schema objects and how this approach can be used to build a complete tool for database evolution There is an increasing need for database evolution facilities oering more ex