Enforcement of Integrity Constraints in Recursive Databases

Integrity constraint(ic) enforcement forms an essential component in deductive database processing. Some interesting methods which enforce integrity constraints have been proposed by Topor, Lloyd, Decker, Kowalski, Sadri, Soper, Martens, Bruynooghe, Yum and Henschen. In this thesis we further analyze and develop efficient simplification algorithms and methods for the enforcement of integrity constraints in recursive deductive databases. We combine theorem-proving methods with compilation techniques in our approach. Theorem-proving methods are used to prune the size of the integrity constraint checking space and compilation techniques are also used to derive necessary implicit modifications and evaluate the simplified integrity constraint set against the actual database. Synchronous and asynchronous chain recursions are discussed. By exploiting the hierarchical structure of a deductive database, we can precompile or partially precompile integrity constraints and ic-relevant rules to simplify integrity constraint checking and validate some modifications by static qualitative analysis. By analyzing predicate connection and variable binding, and compiling recursive rules independently, we can simplify ic-relevant queries and generate efficient checking plans. Some asynchronous and synchronous chain recursive integrity checking relevant queries can be simplified to non-recursive or simpler queries. Efficient processing algorithms are developed for integrity checking and derivation of implicit modification. To perform integrity checking against the actual database we utilize the 'affected graph' of a modification. We achieve by focusing our attention only on the part of the database which is affected by the update and relevant to integrity constraints.