Constraint-Based Termination Analysis of Active Rules

Detecting termination of rules is in general undecidable. Existing static analysis techniques are very conservative, and the current SQL3 standard does not prescribe methods for ensuring termination, so most commercial database products impose a fixed upper limit on the number of cascading rule firings. The commercial solution has undesirable effects e.g. some correct rule firing sequences may prematurely be halted. Since a rule can be viewed as a database state transformer, in this paper, database states are expressed with linear and Boolean hybrid constraints, and processing of rules is simulated based on constraint expressions and constraint solving. This method can obtain more precise conclusion than the existing methods.