Geo Functions
editGeo Functions
editThis functionality is in beta and is subject to change. The design and code is less mature than official GA features and is being provided as-is with no warranties. Beta features are not subject to the support SLA of official GA features.
The geo functions work with geometries stored in geo_point
, geo_shape
and shape
fields, or returned by other geo functions.
Limitations
editgeo_point
, geo_shape
and shape
and types are represented in SQL as
geometry and can be used interchangeably with the following exceptions:
-
geo_shape
andshape
fields don’t have doc values, therefore these fields cannot be used for filtering, grouping or sorting. -
geo_points
fields are indexed and have doc values by default, however only latitude and longitude are stored and indexed with some loss of precision from the original values (4.190951585769653E-8 for the latitude and 8.381903171539307E-8 for longitude). The altitude component is accepted but not stored in doc values nor indexed. Therefore callingST_Z
function in the filtering, grouping or sorting will returnnull
.
Geometry Conversion
editST_AsWKT
editSynopsis:
Input:
Output: string
Description:Returns the WKT representation of the geometry
.
SELECT city, ST_AsWKT(location) location FROM "geo" WHERE city = 'Amsterdam'; city:s | location:s Amsterdam |point (4.850311987102032 52.347556999884546)
ST_WKTToSQL
editSynopsis:
Input:
Output: geometry
Description:Returns the geometry from WKT representation.
SELECT CAST(ST_WKTToSQL('POINT (10 20)') AS STRING) location; location:s point (10.0 20.0)
Geometry Properties
editST_GeometryType
editSynopsis:
Input:
Output: string
Description:Returns the type of the geometry
such as POINT, MULTIPOINT, LINESTRING, MULTILINESTRING, POLYGON, MULTIPOLYGON, GEOMETRYCOLLECTION, ENVELOPE or CIRCLE.
SELECT ST_GeometryType(ST_WKTToSQL('POINT (10 20)')) type; type:s POINT
ST_X
editSynopsis:
Input:
Output: double
Description:Returns the longitude of the first point in the geometry.
SELECT ST_X(ST_WKTToSQL('POINT (10 20)')) x; x:d 10.0
ST_Y
editSynopsis:
Input:
Output: double
Description:Returns the latitude of the first point in the geometry.
SELECT ST_Y(ST_WKTToSQL('POINT (10 20)')) y; y:d 20.0
ST_Z
editSynopsis:
Input:
Output: double
Description:Returns the altitude of the first point in the geometry.
SELECT ST_Z(ST_WKTToSQL('POINT (10 20 30)')) z; z:d 30.0
ST_Distance
editSynopsis:
Input:
Output: Double
Description:Returns the distance between geometries in meters. Both geometries have to be points.
SELECT ST_Distance(ST_WKTToSQL('POINT (10 20)'), ST_WKTToSQL('POINT (20 30)')) distance; distance:d 1499101.2889383635