Multi-Step Processing of Spatial Joins

The spatial join combines spatial objects from a Cartesian product that satisfy certain geometric attributes. Unfortunately, to validate the operation the actual objects must be compared against each other. The authors discussed a new process for reducing the number of items that have to be retrieved from disk and compared through filtering and approximation. The three step pipeline started by using the MBRs of objects within an R-Tree to create an approximation of the join set. The second step filtered the candidates with various tricks, reducing the total number that needed to be checked with their actual geometries. The third step performed the actual checking, but was sped up through better representation of data.