Obtaining the X and Y ordinates of a geometry is important when dealing with XY tables. For
example, the ST_Transform UDF accepts and returns a geometry which means an
XY table cannot be transformed FROM one coordinate system to another. The
ST_X and ST_Y UDFs allow the transformation of an XY table
FROM one coordinate system to another.
Another common need is the ability to filter records in an XY table by the bounds of a
geometry. The ST_XMax, ST_XMin, ST_YMax,
and ST_YMin UDFs provide a way to get the values of the MBR for a writable
geometry.
The following Observer index functions are available: