Automatic Generation of Update Rules to Enforce Consistency Constraints in Design Databases

Database systems for computer-aided design (CAD) are characterised by structural complexity and nonstandard relationship types. Integrity constraints typically describe the semantics of these relationships. Enforcing such constraints in the face of user-initiated changes to the database is necessary to ensure that the database is consistent and the corresponding design is valid. Typically, update rules are specified to maintain integrity constraints. In this paper, we concentrate on the automatic generation of update rules from integrity constraints. Our methodology generates two types of update rules, which are guaranteed to result in a consistent database state. The database designer is provided with the flexibility of alternative semantics as a result of the two update rule types. Tests for integrity violations and repair actions are both generated during a single analysis. The underlying formalism expresses constraints, updates, and rules within the same language; thus the same proof theory applies to all components. This simplifies the overall analysis and enables concise correctness proofs.