This section contains reference documentation for the ST_Distance function.
For geometry type, returns the 2-dimensional cartesian minimum distance (based on spatial ref) between two geometries in projected units. For geography, returns the great-circle distance in meters between two SphericalGeography points. Note that g1, g2 shall have the same type.
ST_Distance(geography/geometry, geography/geometry)
These examples are based on the Streaming Quick Start.
Madrid
POINT (-3.71 40.42)
504376.5534398629