Use ST_AsEWKB to return a WKB string with an SRID - PolarDB

Returns the Well-Known Binary (WKB) string that represents a geometry or geography object. Unlike standard WKB, the output includes the spatial reference identifier (SRID).

Syntax

bytea ST_AsEWKB(geometry g1);
bytea ST_AsEWKB(geometry g1, text NDRorXDR);
bytea ST_AsEWKB(geography g1);
bytea ST_AsEWKB(geography g1, text NDRorXDR);

Parameters

Parameter	Description
`g1`	The geometry or geography object to convert.
`NDRorXDR`	The byte order of the output. Valid values: XDR (big endian), NDR (little endian). Default value: NDR.

Usage notes

The WKB specification does not include SRIDs in standard WKB output. Use ST_AsEWKB when you need a binary representation that embeds the SRID.
Supports circular strings, curves, polyhedral surfaces, triangles, triangulated irregular network (TIN) surfaces, and 3D objects.

Examples

Return EWKB with the default little endian (NDR) byte order:

SELECT ST_AsEWKB(ST_GeomFromText('POLYGON((1 1,1 2,2 2,2 1,1 1))',4326));

Output:

                           st_asewkb
---------------------------------------------------------------
 \x0103000020e61000000100000005000000000000000000f03f000000000.
.000f03f000000000000f03f00000000000000400000000000000040000000.
.00000000400000000000000040000000000000f03f000000000000f03f000.
.000000000f03f
(1 row)

Return EWKB with big endian (XDR) byte order:

SELECT ST_AsEWKB(ST_GeomFromText('POLYGON((1 1,1 2,2 2,2 1,1 1))',4326),'XDR');

Output:

                           st_asewkb
---------------------------------------------------------------
 \x0020000003000010e600000001000000053ff00000000000003ff000000.
.00000003ff000000000000040000000000000004000000000000000400000.
.000000000040000000000000003ff00000000000003ff00000000000003ff.
.0000000000000
(1 row)