Enhancing Sedona (formerly GeoSpark) with Efficient k Nearest Neighbor Join Processing

Abstract

Sedona (formerly GeoSpark) is an in-memory cluster computing system for processing large-scale spatial data, which extends the core of Apache Spark to support spatial datatypes, partitioning techniques, indexes, and operations (e.g., spatial range, k Nearest Neighbor (kNN) and spatial join queries). k Nearest Neighbor Join Query (kNNJQ) finds for each object in one dataset P, k nearest neighbors of this object in another dataset Q. It is a common operation used in numerous spatial applications (e.g., GISs, location-based systems, continuous monitoring, etc.). kNNJQ is a time-consuming spatial operation, since it can be considered a hybrid of spatial join and nearest neighbor search. Given that Sedona outperforms other Spark-based spatial analytics systems in most cases and, it does not support kNN joins, including kNNJQ is a worthwhile challenge. Therefore, in this paper, we investigate how to design and implement an efficient kNNJQ algorithm in Sedona, using the most appropriate spatial partitioning technique and other improvements. Finally, the results of an extensive set of experiments with real-world datasets are presented, demonstrating that the proposed kNNJQ algorithm is efficient, scalable and robust in Sedona. © 2021, Springer Nature Switzerland AG.