Use ST_DWithin to check if two objects are within a specified distance - ApsaraDB RDS

Returns true if two spatial objects are within a specified distance of each other, and false otherwise. Unlike ST_Distance, ST_DWithin automatically uses available spatial indexes, making it the standard choice for proximity queries.

Syntax

boolean ST_DWithin(geometry g1, geometry g2, double precision distanceOfSrid);
boolean ST_DWithin(geography gg1, geography gg2, double precision distanceMeters);
boolean ST_DWithin(geography gg1, geography gg2, double precision distanceMeters, boolean useSpheroid);

Parameters

Parameter	Type	Description
`g1`	geometry	The first geometry object.
`g2`	geometry	The second geometry object.
`distanceOfSrid`	double precision	The threshold distance, in the unit defined by the spatial reference system (SRS) of the geometry objects.
`gg1`	geography	The first geography object.
`gg2`	geography	The second geography object.
`distanceMeters`	double precision	The threshold distance, in meters.
`useSpheroid`	boolean	Specifies whether to use an ellipsoid reference system. If you use an ellipsoid reference system, this function returns a more accurate result but at a slightly lower speed.

Usage notes

When both arguments are geometry, they must share the same spatial reference identifier (SRID).
When both arguments are geography, distance is measured in meters by default.
The function compares bounding boxes using all available spatial indexes, so proximity checks are index-accelerated by design.
For 3D proximity checks, use ST_3DDWithin instead.

Examples

Difference between ST_DWithin and ST_DFullyWithin

ST_DWithin returns true if the shortest distance between the two objects is within the threshold. ST_DFullyWithin is stricter: every point on both objects must be within the threshold.

SELECT ST_DFullyWithin(g1, g2, 2), ST_DWithin(g1, g2, 2)
FROM (
  SELECT 'LINESTRING(0 1,1 1)'::geometry AS g1,
         'LINESTRING(0 0,0 -1)'::geometry AS g2
) AS test;

Expected output:

 st_dfullywithin | st_dwithin
-----------------+------------
 f               | t
(1 row)

What's next

ST_DFullyWithin: checks whether all points on two objects are within a specified distance
ST_3DDWithin: proximity check for 3D objects in a projected coordinate system