Spatial Joins Using R-trees: Breadth-First Traversal with Global Optimizations

R-tree based spatial join is useful because of both its superior performance and the wide spread implementation of R-trees. We present a new R-tree join method called BFRJ (Breadth-First R-tree Join). BFRJ synchronously traverses both R-trees in breadthfirst order while processing join computation one level at a time. At each level, BFRJ creates an intermediate join index and deploys global optimization strategies (ordering, memory management, buffer management) to improve the join computation at the next level. We also present an experimental evaluation of the proposed optimizations as well as a performance comparison between BFRJ and the state-of-the-art approach. Our experimental results indicate that BFRJ with global optimizations can outperform the competitor by a significant margin (up to 50%). This work was supportedin part by the University of Michigan ITS Research Center of Excellence grant (DTFH61-93-X0001i’-Sub) sponsored by the U.S. Dept. of Transportation and by the Michigan Dept. of Transportation. This work was performed while the authors were at the University of Michigan. Permission to copy without fee all OT part of this material is granted provided that the copies are not made OT distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Very Large Data Base Endowment. To copy otherwise, OT to republish, requires a fee and/or special permission from the Endowment. Proceedings of the 23rd VLDB Conference Athens, Greece, 1997