1. A computer-implemented method of spatial query processing, comprising: receiving, by at least one computer processor, a spatial query on spatial data that specifies a query window, where the spatial data has an associated spatial data index, and where the spatial data index includes a plurality of spatial data index elements; constructing, by the at least one computer processor, a query window index structure describing a geometry of the query window, where the query window index structure includes a plurality of query window index structure elements; and comparing, by the at least one computer processor, the query window index structure to the spatial data index to determine a spatial relationship between the query window and the spatial data by: identifying a spatial data index element; searching the query window index structure to determine if the spatial data index element intersects a query window index structure element; if the spatial data index element intersects the query window index structure element, accessing a spatial data store that stores the spatial data to determine if spatial data represented by the spatial data index element intersects the query window; if the spatial data index element does not intersect the query window index structure element, determining whether a selected data point lying in the spatial data index element is contained within the query window; and if the selected data point is contained within the query window, determining that the spatial data represented by the spatial data index element is contained within the query window.