Spatial cohesion queries

Dimitris Sacharidis, Antonios Deligiannakis

Abstract: Given a set of attractors and repellers, the cohesion query returns the point in database that is as close to the attractors and as far from the repellers as possible. Cohesion queries find applications in various settings, such as facility location problems, location-based services. For example, when attractors represent favorable plases, e.g., tourist attractions, and repellers denote undesirable locations, e.g., competitor stores, the cohesion query would return the ideal location, among a database of possible options, to open a new store. These queries are not trivial to process as the best location, unlike aggregate nearest or farthest neighbor queries, may be far from the optimal point in space. Therefore, to achieve sub-linear performance in practice, we employ novel best-first search and branch and bound paradigms that take advantage of the geometrical interpretation of the problem. Our methods are up to orders of magnitude faster than linear scan and adaptations of existing aggregate nearest/farthest neighbor algorithms.