ST_nearestApproachDistance-AnalyticDB(AnalyticDB)-阿里云帮助中心

Returns the minimum distance between a trajectory object and a geometry object within a specified time range. The return type is float8.

Syntax

float8 ST_nearestApproachDistance(trajectory traj, tsrange range, geometry g);
float8 ST_nearestApproachDistance(trajectory traj, timestamp t1, timestamp t2, geometry g);

Two overloads are available: one accepts a tsrange value, the other accepts explicit start and end timestamps.

Parameters

Parameter	Type	Description
`traj`	trajectory	The trajectory object.
`range`	tsrange	The time range.
`t1`	timestamp	The start time.
`t2`	timestamp	The end time.
`g`	geometry	The geometry object to measure distance against.

Example

The following query returns the minimum distance between each trajectory in traj_table and a line segment over a one-hour window.

-- Find the nearest approach distance between each trajectory and a line, from 13:00 to 14:00
SELECT ST_nearestApproachDistance(
  traj,
  '2010-01-01 13:00:00',
  '2010-01-01 14:00:00',
  'LINESTRING(0 0, 5 5, 9 9)'::geometry
) AS nearest_distance
FROM traj_table;