This topic describes the ST_AsBinary function. This function returns the Well-Known Binary (WKB) string that represents a geometry object or a geography object. The WKB string that is returned does not contain spatial reference identifier (SRID) metadata.
Syntax
bytea ST_AsBinary(geometry g1);
bytea ST_AsBinary(geometry g1, text NDRorXDR);
bytea ST_AsBinary(geography g1);
bytea ST_AsBinary(geography g1, text NDRorXDR);
Parameters
Parameter | Description |
---|---|
g1 | The geometry object or geography object whose WKB representation you want to obtain. |
NDRorXDR | The byte order that you want to use. Valid values:
|
Description
- The WKB specification defines that standard WKB strings do not contain SRIDs. If you want to obtain a WKB string that contains an SRID, use the ST_AsEWKB function.
- This function supports circular strings, curves, polyhedral surfaces, triangles, triangulated irregular network (TIN) surfaces, and 3D objects.
Examples
- Obtain a WKB string with the default little endian byte order retained.
SELECT ST_AsBinary(ST_GeomFromText('POLYGON((1 1,1 2,2 2,2 1,1 1))',4326)); st_asbinary --------------------------------------------------------------- \x01030000000100000005000000000000000000f03f000000000000f03f0. .00000000000f03f0000000000000040000000000000004000000000000000. .400000000000000040000000000000f03f000000000000f03f00000000000. .0f03f (1 row)
- Obtain a WKB string with the big endian byte order specified.
SELECT ST_AsBinary(ST_GeomFromText('POLYGON((1 1,1 2,2 2,2 1,1 1))',4326),'XDR'); st_asbinary --------------------------------------------------------------- \x000000000300000001000000053ff00000000000003ff00000000000003. .ff00000000000004000000000000000400000000000000040000000000000. .0040000000000000003ff00000000000003ff00000000000003ff00000000. .00000 (1 row)