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ST_GeoHash

Returns the GeoHash string of a geometry with the given precision.

Usage

string ST_GeoHash(geom: geometry)
string ST_GeoHash(geom: geometry, precision: integer)
string ST_GeoHash(geog: geography)
string ST_GeoHash(geog: geography, precision: integer)

Arguments

  • geog (geography): Input geography
  • precision (integer): Number of base-32 characters in the returned GeoHash.
  • geom (geometry): Input geometry

Description

Encodes the geometry as a base-32 GeoHash string with precision characters. Non-point geometries are encoded using the center of their bounding box. A non-positive precision returns an empty string, and precision is capped at 20 characters.

A GeoHash is defined against the WGS84 datum, so the argument must carry either a WGS84 CRS (EPSG:4326 / OGC:CRS84) or no CRS at all; anything else raises an error. Use ST_Transform() to reproject first. This includes other geographic CRSes such as NAD83, whose units are degrees but whose datum differs from WGS84 by enough to shift the result at high precision.

The same rule applies whether the CRS belongs to the column or to the individual rows; only the timing differs. A column-level CRS is known while the query is planned, so it is rejected before any row is read. A row-level CRS is not known until the row is reached, so it is rejected then. To encode only the WGS84 rows of a mixed column, filter them first — WHERE ST_SRID(geom) = 4326 is applied before the encoding, so the other rows never reach it.

Latitudes outside -90 to 90 return NULL. Longitudes outside -180 to 180 are wrapped back into range when the argument declares a WGS84 CRS, so a longitude of 181 encodes as -179; without a declared CRS they return NULL instead, matching Apache Sedona.

When precision is omitted, the argument must be a POINT and is encoded at the maximum precision of 20 characters. Any other geometry type raises an error, because there is no single obvious precision for a geometry that covers an area.

Geography arguments are bounded on the sphere and require the s2geography bounder to be registered on the session.

Examples

SELECT ST_GeoHash(ST_GeomFromWKT('POINT (21.4234 52.0423)'), 10);

┌───────────────────────────────────────────────────────────────────────┐
│ st_geohash(st_geomfromwkt(Utf8("POINT (21.4234 52.0423)")),Int64(10)) │
│                                  utf8                                 │
╞═══════════════════════════════════════════════════════════════════════╡
│ u3r0pd0037                                                            │
└───────────────────────────────────────────────────────────────────────┘

SELECT ST_GeoHash(ST_GeomFromWKT('POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))'), 8);

┌──────────────────────────────────────────────────────────────────────────────┐
│ st_geohash(st_geomfromwkt(Utf8("POLYGON ((0 0, 2 0, 2 2, 0 2, 0 0))")),Int64 │
│                                     (8))…                                    │
╞══════════════════════════════════════════════════════════════════════════════╡
│ s00twy01                                                                     │
└──────────────────────────────────────────────────────────────────────────────┘

SELECT ST_GeoHash(ST_GeomFromWKT('POINT (21.4234 52.0423)'));

┌─────────────────────────────────────────────────────────────┐
│ st_geohash(st_geomfromwkt(Utf8("POINT (21.4234 52.0423)"))) │
│                             utf8                            │
╞═════════════════════════════════════════════════════════════╡
│ u3r0pd0037ugg6hm1kb1                                        │
└─────────────────────────────────────────────────────────────┘