Schema evolution in object databases by catalogs

Pons, A; Keller, R. K.
Pons, A
Keller, R
Proc. IDEAS 1997
Citations range: 
10 - 49

We are concerned by schema evolution in Object Oriented Databases (OODB) that is processed by a modification on the
classes on the schema. We present a new categorization of the different modifications in three categories : primitive,
composite and complexe modifications. On this basis, we propose a method by decomposition for addressing conceptual
schema evolution: real-life, complex schema modifications are solved by decomposition into simpler, well-known and
controlled modifications, called composites, which in turn may be reduced to so-called primitives. A key step in making
this approach practical, is the provision of two catalogs: one for the primitives based on a sound object model and one for
the composites. Such catalogs raise the level of abstraction, further reuse and are prerequisites for effective tool support.
In this paper, we define the three types of schema modifications, describe these catalogs, put them into the context of our
decomposition approach and provide a process for schema evolution.