Data Organization Issues for Location-Dependent Queries in Mobile Computing

We consider queries which originate from a mobile unit and whose result depends on the location of the user who initiates the query. Examples of such queries arc: find the nearest service provider, what are the traffic conditions on a roUie. We execute such queries based on location-dependent dala involved in their processing. To facilitate location-dependent query processing, we build concept hierarchies [3] based on location. These hierarchies define mapping among different granularities of locations. One such hierarchy is to generate domain knowledge about Ihe cities that belong 10 a state. The hierarchies are also used as distributed directories to assist in finding the database or relation that contains the values of the locationdependent aHribute in a particular location. We eXlend concept hierarchies to include spatial indexes on the location-dependent attributes. Finally, we discuss how 10 partition and replicale relations based on the location (0 process the queries efficientlY. We briefly discuss the implementalion issues.