Schema Evolution and Integration
- Stewart M. Clamen
Distributed and Parallel Databases,
2(1):101-126, January 1994.
Providing support for schema evolution allows existing databases
to be adjusted for varying roles over time. This paper reflects on
existing evolution support schemes and introduces a more general and
functional mechanism to support schema evolution and instance
adaptation for centralized and distributed object-oriented database
Our evolution support scheme is distinguished from previous mechanisms
in that it is primarily concerned with preserving existing database
objects and maintaining compatibility for old applications, while
permitting a wider range of evolution operations. It achieves this by
supporting schema versioning, allowing multiple representations of
instances to persist simultaneously, and providing for programmer
specification of how to adapt existing instances.
The mechanism is general enough to provide much of the support
necessarily for heterogeneous schema integration, as well as
incorporating much of the features of object migration and
schema evolution, heterogeneous schema integration,
object-oriented database systems, instance adaptation.