Splitting polygons with interior rings

A computer program, stored in a non-transitory storage medium, the program comprising executable instructions that cause a computer to:

• consider a spatial feature for storage in a database system running on a computer, the spatial feature comprising:
• a polygon, P, comprising:
• an outer ring, OR, and the area within the outer ring;
• the outer ring comprising:
• a plurality of vertices, designated ORV1, . . . ORVM, with the vertex designated ORV1 being the first vertex, the vertex designated ORVM being the last vertex, vertices having consecutive numbers after “ORV” in their respective designations being consecutive vertices, and the first and last vertex being the same so that ORV1=ORVM;
• lines connecting consecutive vertices;
• and
• an interior ring contained within the polygon;
• a) remove the interior ring from the polygon;
• b) determine a line along which to split the polygon without regard for the location of the inner ring within the polygon;
• c) split the polygon into two polygons, SP1 and SP2, along the line;
• d) apply the interior ring to the two split polygons by invoking a point set difference between the interior ring and the two split polygons;
• and
• e) store the split polygons in the database system on the computer.

A database system comprising:

• one or more nodes;
• a plurality of CPUs, each of the one or more nodes providing access to one or more CPUs;
• a plurality of virtual processes, each of the one or more CPUs providing access to one or more virtual processes;
• each virtual process configured to manage data, including rows from the set of database table rows, stored in one of a plurality of data-storage facilities;
• a process that:
• considers a spatial feature for storage in the database system, the spatial feature comprising:
• a polygon, P, comprising:
• an outer ring, OR, and the area within the outer ring;
• the outer ring comprising:
• a plurality of vertices, designated ORV1, . . . ORVM, with the vertex designated ORV1 being the first vertex, the vertex designated ORVM being the last vertex, vertices having consecutive numbers after “ORV” in their respective designations being consecutive vertices, and the first and last vertex being the same so that ORV1=ORVM;
• lines connecting consecutive vertices;
• and
• an interior ring contained within the polygon;
• a) removes the interior ring from the polygon;
• b) determines a line along which to split the polygon without regard for the location of the inner ring within the polygon;
• c) splits the polygon into two polygons, SP1 and SP2, along the line;
• d) applies the interior ring to the two split polygons by invoking a point set difference between the interior ring and the two split polygons;
• and
• e) stores the split polygons in the database system on the computer.