Inexact Retrieval of Multiway Spatial Joins

Inexact retrieval of multiway spatial joins refers to the cases where (i) there is limited time for query processing and the goal is to retrieve the best possible solutions within this limit (ii) there is unlimited time and the goal is to retrieve a single exact solution, if such a solution exists, or the best approximate one otherwise. The first case is motivated by the high cost of join processing in realtime systems involving large amounts of multimedia data, while the second one is motivated by applications that require “negative” examples. This papers proposes several algorithms for query processing under theses conditions. For the limited-time case we develop some non-deterministic search heuristics that can quickly retrieve good solutions. However, these heuristics are not guaranteed to find the best solutions, even without a time limit. Therefore, for the unlimited-time case we propose systematic search algorithms tailored specifically for the efficient retrieval of a single solution. Both types of algorithms are integrated with R-trees in order to prune the search space. Our proposal is evaluated with extensive experimental comparison. Contact Author: Dimitris Papadias Tel: ++852-23586971 http://www.cs.ust.hk/~dimitris/ Fax: ++852-23581477 E-mail: [email protected] The Hong Kong University of Science & Technology Technical Report Series Department of Computer Science Inexact Retrieval of Multiway Spatial Joins Dimitris Papadias, Dinos Arkoumanis 2 Technical Report HKUST-CS00-05 December, 2000