CDIS: an Engineering Constraint Definition and Integrity Enforcement System for Relational Databases

Abstract

Database management systems (DBMS) are an essential component of the computer integrated manufacturing (CIM) environment. A database management system provides a powerful functionality for the storage, management, and use of engineering data. It is lacking, however, in its ability to deal with engineering constraints. In the past, constraint checking was performed by application programs. More recently DBMS's have been incorporating into their structure specifications for enforcing a limited set of integrity constraints and the mechanisms for invoking them automatically. To ensure the correctness of engineering data, an effective constraint management capability must be incorporated into any proposed engineering DBMS. This paper demonstrates how this can be done, proposes a systematic way to classify constraints so that integrity can be maintained efficiently, and discusses a prototype called CDIS which implements the concepts. This paper uses the relational database model to represent both engineering data and engineering constraints. Data integrity is defined and its enforcement through the use of engineering constraints is described. Existing methods for handling constraints are discussed. A new model that enables the engineer to associate design constraints with a relational database is presented and an example is given that demonstrates the model. Extensions to a DBMS to implement the concepts presented are described. No currently available DBMS provides the much needed capabilities proposed her