ST_AsTWKB-ApsaraDB RDS(RDS)-阿里云帮助中心

Returns the Tiny Well-Known Binary (TWKB) representation of one or more geometry objects as a bytea value.

Syntax

Single geometry

bytea ST_AsTWKB(
    geometry  g1,
    integer   decimaldigitsXY,
    integer   decimaldigitsZ,
    integer   decimaldigitsM,
    boolean   includeSizes,
    boolean   includeBoundingBoxes
);

Geometry array with unique IDs

bytea ST_AsTWKB(
    geometry[]  geometries,
    bigint[]    uniqueIds,
    integer     decimaldigitsXY,
    integer     decimaldigitsZ,
    integer     decimaldigitsM,
    boolean     includeSizes,
    boolean     includeBoundingBoxes
);

Parameters

Parameter	Type	Default	Description
`g1`	geometry	—	The geometry object to encode as TWKB.
`geometries`	geometry[]	—	The geometry objects to encode as TWKB.
`uniqueIds`	bigint[]	—	The unique identifiers of the geometry objects in `geometries`.
`decimaldigitsXY`	integer	0	The number of decimal places to retain in the x and y coordinates.
`decimaldigitsZ`	integer	0	The number of decimal places to retain in the z coordinate.
`decimaldigitsM`	integer	0	The number of decimal places to retain in the m coordinate.
`includeSizes`	boolean	false	Specifies whether to include the size of each geometry object in the output.
`includeBoundingBoxes`	boolean	false	Specifies whether to include the bounding box of each geometry object in the output.

Examples

Convert a point geometry to its TWKB representation:

SELECT ST_AsTWKB(ST_GeomFromText('POINT(116 40)', 4326));

Output:

       st_astwkb
------------------------
 \xa1008082880b80a4e803
(1 row)