A Formal Model for Temporal Schema Versioning in Object-Oriented Databases

In this paper we present a formal model for the support of temporal schema versions in object-oriented databases. Its definition is partially based on a generic (ODMG compatible)object model and partially introduces new concepts. The proposed model supports all the schema changes which are usually considered in the OODB literature, for which an operational semantics and a formal analysis of their correct behaviour is provided. Semantic issues arising from the introduction of temporal schema versioning in a conventional or temporal database (concerning the interaction between the intensional and extensional levels of versioning and the management of data in the presence of multiple schema versions) are also considered.