Improving integrity constraint checking for stratified deductive databases

Abstract

Integrity checking for stratifiable deductive databases has been studied by many authors. In order to handle recursive relations, most of these methods adopt update driven approach to validate each given constraint. These methods start their algorithm from the given update and perform some operations (refutations) until it reaches the constraint formula. However, when the update is irrelevant to the constraint, these methods still perform their operations only to find that the constraint formula cannot be violated. In this case considerable effort is wasted. In this paper, we shall explore this problem and propose a set called relevant-set which can be incorporated with most of these existing constraint checking methods, to detect some of these unnecessary checkings. The relevant-set needs only to be calculated once for each integrity constraint. Furthermore, the set can also take advantage of some evaluable functions in the constraint and rules so that more unnecessary checkings can be detected.