Type Evolution and Instance Adaptation
- Stewart M. Clamen
- Technical Report No. CMU-CS-92-133
- Carnegie Mellon University School of Computer Science, Pittsburgh, PA,
- May 1991
ABSTRACT
Schema evolution support is an important facility for object-oriented
database (OODB) systems. While existing OODB systems provide for
limited forms of evolution, including modification to the database
schema and reorganization of affected instances, we find their support
insufficient. Specific deficiencies are 1) the lack of compatibility
support for old applications, and 2) the lack of ability to install
arbitrary changes upon the schema and database. This paper examines
the limitations of existing schemes, and offers a more general
framework for specifying and reasoning about the evolution of class
definitions and the adaptation of existing, persistent instances to
those new definitions.
Keywords
Schema evolution; object-oriented databases; class versioning;
instance adaptation; compatibility.