CAT: Correct Answers of Continuous Queries Using Triggers
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 [1,2]). 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 veri.ed and updated, and the answer-set of Q1 has to be re-evaluated in every clock-tick1. However, the re-evaluation of such queries can be avoided if an update to the MOD does not a.ect the answer-set.
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