H2GIS

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ST_Holes

Signatures

GEOMETRYCOLLECTION ST_Holes(GEOMETRY geom)
GEOMETRYCOLLECTION ST_Holes(GEOMETRYCOLLECTION geom)

Description

Returns geom’s holes as a GEOMETRYCOLLECTION.

Returns GEOMETRYCOLLECTION EMPTY for Geometries of dimension less than 2.

Examples

SELECT ST_Holes('POLYGON((0 0, 10 0, 10 5, 0 5, 0 0))');
-- Answer: GEOMETRYCOLLECTION EMPTY

SELECT ST_Holes('POLYGON((0 0, 10 0, 10 5, 0 5, 0 0),
                          (1 1, 2 1, 2 4, 1 4, 1 1))');
-- Answer: GEOMETRYCOLLECTION(POLYGON((1 1, 2 1, 2 4, 1 4, 1 1)))

SELECT ST_Holes(
    'GEOMETRYCOLLECTION(
       POLYGON((0 0, 10 0, 10 5, 0 5, 0 0),
                (1 1, 2 1, 2 4, 1 4, 1 1)),
       POLYGON((11 6, 14 6, 14 9, 11 9, 11 6),
                (12 7, 14 7, 14 8, 12 8, 12 7)))');
-- Answer: GEOMETRYCOLLECTION(
--           POLYGON((1 1, 2 1, 2 4, 1 4, 1 1)),
--           POLYGON((12 7, 14 7, 14 8, 12 8, 12 7)))

SELECT ST_Holes('LINESTRING(5 5, 1 2, 3 4, 9 3)');
-- Answer: GEOMETRYCOLLECTION EMPTY
See also