ST_AsBinary
Name
ST_AsBinary — Return the Well-Known Binary (WKB) representation of the geometry/geography without SRID meta data.
Synopsis
bytea
ST_AsBinary
(
geometry
g1
)
;
bytea
ST_AsBinary
(
geometry
g1
, text
NDR_or_XDR
)
;
bytea
ST_AsBinary
(
geography
g1
)
;
bytea
ST_AsBinary
(
geography
g1
, text
NDR_or_XDR
)
;
Description
Returns the Well-Known Binary representation of the geometry. There are 2 variants of the function. The first variant takes no endian encoding parameter and defaults to server machine endian. The second variant takes a second argument denoting the encoding - using little-endian ('NDR') or big-endian ('XDR') encoding.
This is useful in binary cursors to pull data out of the database without converting it to a string representation.
![[Note]](images/note.png)
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The WKB spec does not include the SRID. To get the WKB with SRID format use ST_AsEWKB |
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ST_AsBinary is the reverse of ST_GeomFromWKB for geometry. Use ST_GeomFromWKB to convert to a postgis geometry from ST_AsBinary representation. |
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The default behavior in PostgreSQL 9.0 has been changed to output bytea in hex encoding. ST_AsBinary is the reverse of ST_GeomFromWKB for geometry. If your GUI tools require the old behavior, then SET bytea_output='escape' in your database. |
Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.
Enhanced: 2.0.0 support for higher coordinate dimensions was introduced.
Enhanced: 2.0.0 support for specifying endian with geography was introduced.
Availability: 1.5.0 geography support was introduced.
Changed: 2.0.0 Inputs to this function can not be unknown -- must be geometry. Constructs such as
ST_AsBinary('POINT(1 2)')
are no longer valid and you will get an
n st_asbinary(unknown) is not unique error
. Code like that
needs to be changed to
ST_AsBinary('POINT(1 2)'::geometry);
. If that is not possible, then install
legacy.sql
.
This method implements the
OpenGIS Simple Features
Implementation Specification for SQL 1.1.
s2.1.1.1
This method implements the SQL/MM specification. SQL-MM 3: 5.1.37
This method supports Circular Strings and Curves
This function supports Polyhedral surfaces.
This function supports Triangles and Triangulated Irregular Network Surfaces (TIN).
This function supports 3d and will not drop the z-index.
Examples
SELECT ST_AsBinary(ST_GeomFromText('POLYGON((0 0,0 1,1 1,1 0,0 0))',4326));
st_asbinary
--------------------------------
\001\003\000\000\000\001\000\000\000\005
\000\000\000\000\000\000\000\000\000\000
\000\000\000\000\000\000\000\000\000\000
\000\000\000\000\000\000\000\000\000\000
\000\000\000\360?\000\000\000\000\000\000
\360?\000\000\000\000\000\000\360?\000\000
\000\000\000\000\360?\000\000\000\000\000
\000\000\000\000\000\000\000\000\000\000\000
\000\000\000\000\000\000\000\000
(1 row)
SELECT ST_AsBinary(ST_GeomFromText('POLYGON((0 0,0 1,1 1,1 0,0 0))',4326), 'XDR');
st_asbinary
--------------------------------
\000\000\000\000\003\000\000\000\001\000\000\000\005\000\000\000\000\000
\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000
\000?\360\000\000\000\000\000\000?\360\000\000\000\000\000\000?\360\000\000
\000\000\000\000?\360\000\000\000\000\000\000\000\000\000\000\000\000\000\000
\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000
(1 row)