A propagation mechanism for populated schema versions

Object-oriented database systems (OODBMS) offer powerful modeling concepts as required by advanced application domains like CAD/CAM/CAE or office automation. Typical applications have to handle large and complex structured objects which frequently change their value and their structure. As the structure is described in the schema of the database, support for schema evolution is a highly required feature. Therefore, a set of schema update primitives must be provided which can be used to perform the required changes, even in the presence of populated databases and running applications. In this paper, we use the versioning approach to schema evolution to support schema updates as a complex design task. The presented propagation mechanism is based on conversion functions that map objects between different types and can be used to support schema evolution and schema integration.