Authors: Jun Feng, Chunyan Lu, Shimin Xu, Toyohide Watanabe
Addresses: College of Computer and Information Engineering, Hohai University, Nanjing Jiangsu 210098, China. ' College of Computer and Information Engineering, Hohai University, Nanjing Jiangsu 210098, China. ' College of Computer and Information Engineering, Hohai University, Nanjing Jiangsu 210098, China. ' Department of Systems and Social Informatics, Graduate School of Information Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
Abstract: Recently, many spatio-temporal applications pay attention to the summarised information of moving objects in road networks (e.g., the number of vehicles, the average speed). Existing sketch method can solve the distinct counting problem, but without provable guarantees on the approximate quality of aggregate queries over moving objects in road networks in all situations. This paper proposes a dynamic sketch method (DynSketch index) by using existing histogram technique to intelligently partition the sketch method, and to improve the quality of the approximation. Evaluation shows this new method outperforms the sketch method in space consumption, queries efficiency, approximate errors control, and does well in small region queries especially.
Keywords: aggregate query; sketch index; histograms; Dynsketch index; road networks; moving objects; intelligent partitioning; vehicle numbers; average speed.
International Journal of Intelligent Defence Support Systems, 2009 Vol.2 No.2, pp.120 - 137
Published online: 21 Sep 2009 *Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article