Schema evolution in OODBs using class versioning
Simon Monk, Ian Sommerville · ACM SIGMOD Record · 1993
This paper describes work carried out on a model for the versioning of class definitions in an object-oriented database. By defining update and backdate functions on attributes of the previous and current version of a class definition, instances of any version of the class can be converted to instances of any other version. This allows programs written to access an old version of the schema to still use data created in the format of the changed schema.