postgresql – ST_Distance的返回值单位

>所有建筑物和
>所有医院

在从OSM导入的地图中.

我使用以下查询：

SELECT building_id,hospital_id,ST_Distance(building_centroid,hospital_location)
FROM 
(
select planet_osm_polygon.osm_id building_id,ST_Centroid(planet_osm_polygon.way) building_centroid
from planet_osm_polygon
where building = 'yes'
) buildings,(
select planet_osm_point.osm_id hospital_id,planet_osm_point.way hospital_location
from planet_osm_point  
where amenity = 'hospital') hospitals

我得到奇怪的结果 – 距离总是小于1.

如何知道这些值被报告的单位？

更新1：样品结果：

更新2：此查询似乎工作

SELECT building_id,ST_Distance_sphere(building_centroid,hospital_location) distance
FROM 
(
select planet_osm_polygon.osm_id building_id,ST_Centroid(planet_osm_polygon.way)  building_centroid
from planet_osm_polygon
where building = 'yes'
) buildings,planet_osm_point.way hospital_location
from planet_osm_point  
where amenity = 'hospital') hospitals
ORDER BY distance