Adaptive multi-level hashing for moving objects

Abstract

Although several sophisticated index structures for moving objects have been proposed, the hashing method based on a simple grid has been widely employed due to its simplicity. Since the performance of the hashing is largely affected by the size of a grid cell, it should be carefully decided with regard to the workload. In many real applications, however, the workload varies dynamically as time, for example the traffic in the commuting time vs. that in the night. The basic hashing cannot handle this dynamic workload because the cell size cannot be changed during the execution. In this paper, we propose the adaptive multi-level hashing to support the dynamic workload efficiently. The proposed technique maintains two levels of the hashes, one for fast moving objects and the other one for quasi-static objects. A moving object changes its level adaptively according to the degree of its movement. © Springer-Verlag Berlin Heidelberg 2005.