ST_Touches — Tests if two geometries have at least one point in common, but their interiors do not intersect
boolean ST_Touches(
geometry
A, geometry
B)
;
Returns TRUE
if A and B intersect,
but their interiors do not intersect. Equivalently, A and B have at least one point in common,
and the common points lie in at least one boundary.
For Point/Point inputs the relationship is always FALSE
,
since points do not have a boundary.
In mathematical terms: ST_Touches(A, B) ⇔ (Int(A) ⋂ Int(B) = ∅) ∧ (A ⋂ B ≠ ∅)
This relationship holds if the DE9IM Intersection Matrix for the two geometries matches one of:
FT*******
F**T*****
F***T****
This function automatically includes a bounding box comparison
that makes use of any spatial indexes that are available on the geometries.
To avoid using an index, use 
Enhanced: 3.0.0 enabled support for 
This method implements the OGC Simple Features Implementation Specification for SQL 1.1. s2.1.1.2 // s2.1.13.3
This method implements the SQL/MM specification. SQLMM 3: 5.1.28
The ST_Touches
predicate returns TRUE
in the following examples.






SELECT ST_Touches('LINESTRING(0 0, 1 1, 0 2)'::geometry, 'POINT(1 1)'::geometry); st_touches  f (1 row) SELECT ST_Touches('LINESTRING(0 0, 1 1, 0 2)'::geometry, 'POINT(0 2)'::geometry); st_touches  t (1 row)