Distributed Spatial and Spatio-Temporal Join on Apache Spark.

Effective processing of extremely large volumes of spatial data has led to many organizations employing distributed processing frameworks. Apache Spark is one such open source framework that is enjoying widespread adoption. Within this data space, it is important to note that most of the observational data (i.e., data collected by sensors, either moving or stationary) has a temporal component or timestamp. To perform advanced analytics and gain insights, the temporal component becomes equally important as the spatial and attribute components. In this article, we detail several variants of a spatial join operation that addresses both spatial, temporal, and attribute-based joins. Our spatial join technique differs from other approaches in that it combines spatial, temporal, and attribute predicates in the join operator. In addition, our spatio-temporal join algorithm and implementation differs from others in that it runs in commercial off-the-shelf (COTS) application. The users of this functionality are assumed to be GIS analysts with little if any knowledge of the implementation details of spatio-temporal joins or distributed processing. They are comfortable using simple tools that do not provide the ability to tweak the configuration of the algorithm or processing environment. The spatio-temporal join algorithm behind the tool must always succeed, regardless of input data parameters (e.g., it can be highly irregularly distributed, contain large numbers of coincident points, it can be extremely large, etc.). These factors combine to place additional requirements on the algorithm that are uncommonly found in the traditional research environment. Our spatio-temporal join algorithm was shipped as part of the GeoAnalytics Server [12], part of the ArcGIS Enterprise platform from version 10.5 onward.