A theory of attribute equivalence in databases with application to schema integration

Logical database design and global schema design require schema integration. Some of the problems that arise in schema integration are: 1. naming conflicts, 2. scale difference, 3. differences in the level of abstraction of attributes, 4. differences in object identifiers, and 5. differences in representation. The equivalence of attributes is studied. It is shown that relationships and entity sets can be integrated if their identifying attributes can be integrated. Equivalences between object classes and between relationship sets are defined. Several strategies for attribute integration are presented and evaluated. A schema integration tool is designed and implemented.