* ST_CleanGeometry(geometry)
Attempt to make invalid geometry valid
-* ST_SplitGeometry(polygon, line) returns components of polygon
-* ST_SplitGeometry(lineA, lineB) returns components of lineA
-* ST_SplitGeometry(line, point) returns components of line
* ST_AverageDistance(g1 geometry, g2 geometry, nsamples integer) returns double
Sum of minimum distances at regular intervals up two geometries,
divided by the number of samples.