ST_TOUCHES

Returns TRUE if two GEOGRAPHY objects share at least one point on their boundaries, while their interiors do not intersect.

This function is symmetric:

• ST_TOUCHES(A, B) = ST_TOUCHES(B, A)

See also:

• ST_INTERSECTS
• ST_CROSSES

Syntax

ST_TOUCHES(<a>, <b>)

Arguments

• <a> and <b>: Two GEOGRAPHY objects to test

Returns

Returns a BOOLEAN:

• TRUE if the geographies touch (share boundary points but no interior points)
• FALSE if the geographies don't touch or if either input is a point (points have no boundary)

Example

SELECT ST_TOUCHES('POLYGON((0 0, 1 0, 1 1, 0 1, 0 0))'::GEOGRAPHY,
                  'POLYGON((1 0, 2 0, 2 1, 1 1, 1 0))'::GEOGRAPHY);
-- TRUE