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    ApsaraDB RDS:ST_AsText

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    ApsaraDB RDS:ST_AsText

    Last Updated:Mar 28, 2026

    Converts a geographic grid object to its text representation in a specified encoding standard.

    Syntax

    -- Convert a GeomGrid scalar to text
text ST_AsText(geomgrid grid,
               integer precision DEFAULT -1,
               bool separated DEFAULT false,
               text standard DEFAULT 'GGER')

-- Convert a GeomGrid array to a text array
text[] ST_AsText(geomgrid[] grid,
                 integer precision DEFAULT -1,
                 bool separated DEFAULT false,
                 text standard DEFAULT 'GGER')

-- Convert an H3Grid to text
text ST_AsText(h3grid grid)

    Parameters

    ParameterTypeDefaultDescription
    gridGeomGrid or H3Grid—The geographic grid object to convert.
    precisioninteger-1The precision level for the output. Valid values: 1 to 32. Set to -1 to use the precision stored in the grid.
    separatedBooleanfalseSpecifies whether to use split encoding. Applies to 3D GeoSpatial Grid Encoding Rule (GGER) grids.
    standardtext'GGER'The encoding standard. The only supported value is GGER (GeoSpatial Grid Encoding Rule), developed by the Ministry of Natural Resources of the People's Republic of China.

    Description

    ST_AsText encodes a geographic grid as text based on the precision level and encoding standard you specify.

    Note: If the precision you specify is higher than the precision stored in the grid, the output is not zero-padded to fill the gap.

    When split encoding is enabled (separated = true), the horizontal and height components are returned separately. The height encoding is the binary text code for the grid's index value in the height dimension:

    • If the grid is above the surface, the height encoding starts with +.

    • If the grid is below the surface, the height encoding starts with -.

    Examples

    Use the default precision level

    WITH g AS (
  SELECT unnest(ST_AsGrid(
    ST_geomfromtext('POINT(116.31522216796875 39.910277777777778)', 4490), 15)) AS grid)
SELECT ST_AsText(grid) FROM g;
        st_astext
------------------
 G001310322230230

    Specify an output precision level

    WITH g AS (
  SELECT unnest(ST_AsGrid(
    ST_geomfromtext('POINT(116.31522216796875 39.910277777777778)', 4490), 15)) AS grid)
SELECT ST_AsText(grid, 8) FROM g;
      st_astext
-------------
 G00131032

    3D encoding

    SELECT unnest(ST_AsText(
  ST_As3DGrid('srid=4490;POINT(116.31522216796875 39.910277777777778 1001.8)'::geometry, 20)));
             unnest
------------------------
 GZ00262064446046072072

    Split encoding

    The horizontal and height components are returned as separate values. The + prefix on the height value indicates the grid is above the surface.

    SELECT unnest(ST_AsText(
  ST_As3DGrid('srid=4490;POINT(116.31522216796875 39.910277777777778 1001.8)'::geometry, 20),
  -1, true));
                  unnest
-------------------------------
 G00131032223023031031, +10010

    H3 encoding

    SELECT ST_AsText(ST_H3FromLatLng(20.5, 128.2, 8));
         st_astext
-----------------
 884a126689fffff

    See also

    • ST_AsGrid — converts a geometry to a GeomGrid

    • ST_As3DGrid — converts a 3D geometry to a GeomGrid with height

    • ST_H3FromLatLng — creates an H3Grid from latitude and longitude coordinates