An Evaluation of Access Methods for Spatial Networks

Current Spatial Database Management Systems (SDBMS) provide eecient access methods and operators for point and range queries over collections of spatial points, line segments , and polygons. However, it is not clear if they can ef-ciently support network computations which traverse line-segments in a spatial network based on connectivity rather than geographic proximity. It can be shown that the expected I/O cost for many network operations can be reduced by maximizing the Weighted Connectivity Residue Ratio (WCRR). In this paper we compare traditional access methods to a connectivity clustered access method, CCAM, which tries to achieve high WCRR. We also describe possible modiications to improve the WCRR achieved by existing spatial access methods. Experiments with network computations on the Minneapolis road-map show that CCAM performs best even though the proposed modiications substantially improve the performance of existing spatial access methods.