ST_Distance
ST_Distance(g1,g2)
Calculates the shortest distance between two spatial objects. Note that this will return a distance in degrees.
To obtain an accurate distance in meters, the to_spherical_geography() function should be used as described in the
Presto documentation.
Parameters
| Parameter | Type | Description |
|---|---|---|
g1 |
Geometry |
The spatial location of the first location defined using the WKT notation |
g2 |
Geometry |
The spatial location of the second location defined using the WKT notation |
Returns
double - The degrees of arc
Usage
To define a geofence using ST_Distance(), your query will look like this:
SELECT *
FROM geospock.default.largetable AS large,
geospock.default.smalltable AS small
WHERE ST_Distance(ST_Point(small.longitude, small.latitude), ST_Point(large.longitude, large.latitude)) < small.radius;
Example
SELECT *
FROM geospock.default.largetable AS large,
geospock.default.smalltable AS small
WHERE ST_Distance(ST_Point(small.longitude, small.latitude), ST_Point(large.longitude, large.latitude)) < 0.0005;
If you are using a Hive table to provide the locations of the POIs, the relevant fields in that
able must be named latitude and longitude in order for the optimization to take place. In
addition, the fields must be of type double, decimal or float/real.