Schema Versions in Object-Oriented Database Systems

Object-oriented database management systems (OODBMS) are especially suited to model complex and highly dynamic application domains. In this paper, we propose a schema uersioning approach which supports the dynamic change of an objectoriented database schema while it is used by running applications. OUT mechanism allows to have applications working with diflerent schema weTsions on top of the same single database in parallel. A flexible and parameterized approach is presented to make instances of the database accessible in different versions of a schema. In this way, it is no longer required to update all database applications at once whenever the schema is changed. Instead, the adaptation of aid applications to a new schema version can be done 1ateT if this is considered advantageous.