Measuring triggering-interaction complexity on active databases

Distinct software metrics have been proposed for programs. By contrast, metrics for databases have been neglected on the grounds that databases were mere plain files that do not affect considerably information systems maintainability. However, later enhancements on database systems have considerable increase the complexity of the elements kept within the database realm. Such complexity makes metrics a valuable tool to understand, monitor, control, predict and improve software development and maintenance database projects. Triggers are a case in point. Several reports warned about the difficulties to cope with large sets of triggers. Based on the difficulty to ascertain the causes that make a given rule to be triggered, this paper proposes three different metrics for measuring trigger complexity, namely, the triggering potential, the number of anchors and the distance of a trigger. These measures are characterised above the level of the ordinal scale using the measurement theory. Validation of the proposed metrics has been conducted through a set of empirical experiments. (C) 2001 Published by Elsevier Science Ltd.