Description
The ST_HexHash function returns a unique well-known string ID for the grid
cell. The ID then is sortable and searchable that corresponds to the specified X, Y, and
precision.
Syntax
ST_HexHash(Number|String X, Number|String Y, Number precision)
Parameters
| Parameter |
Type |
Description |
|
X
|
Number or String |
The longitude value of the point. |
|
Y
|
Number or String |
The latitude value of the point. |
|
precision
|
Number |
The length of the string key to be returned. The precision determines how large
the grid cells are (longer strings means higher precision and smaller grid
cells). |
Return Values
| Return Type |
Description |
| String |
The ID of the grid cell at the specified precision that contains the
point. |
Examples
SELECT ST_HexHash(x, y, precision) FROM table;
SELECT ST_HexHash(-73.750333, 42.736103, 3);
CREATE TEMPORARY TABLE tmptbl AS
SELECT *, (ST_HexHash(x, y, 10)) AS hashID
FROM coordinates ORDER BY hashID;
INSERT INTO TABLE coordinates_with_hash
SELECT *, (ST_HexHash(x, y, 10)) AS hashID
FROM coordinates ORDER BY hashID;
SELECT c.hashID, ST_ToWKT(ST_HexagonBoundary(c.hashID)),
count (*) AS quantity FROM (SELECT ST_HexHash(x, y, 10)
AS hashID FROM coordinates)
c GROUP BY c.hashID;