Returns the specified interior ring of an ST_Geometry type that represents an ST_Polygon value.
Valid Data Types
This method can be called on 3D geometries (those that include z coordinates). However, the z coordinate is ignored in method calculations. Consequently, any z coordinates returned by this method should be ignored. Teradata recommends using the Make_2D method to strip out the z coordinates of the return value.
Returns an ST_LineString.