CAT: Correct Answers of Continuous Queries Using Triggers

摘要

Consider the query Q1: Retrieve all the motels which will be no further then 1.5 miles from my route, sometime between 7:00PM and 8:30PM, which a mobile user posed to the Moving Objects Database (MOD). Processing such queries is of interest to wide range of applications (e.g. tourist information systems and context awareness). These queries pertain to the future of a dynamic world. Since MOD is only a model of the objects moving in the real world, the accuracy of the representation has to be continuously verified and updated, and the answer-set of Q1 has to be re-evaluated in every clock-tick. However, the re-evaluation of such queries can be avoided if an update to the MOD does not affect the answer-set.