ST_Equals

Determines if two spatial objects are spatially equivalent. The coordinates of the two objects and their WKT/WKB representations must match exactly for ST_Equals to return TRUE.

The order of the points do not matter in determining spatial equivalence:

• LINESTRING(1 2, 4 3) equals LINESTRING(4 3, 1 2).

• POLYGON ((0 0, 1 1, 1 2, 2 2, 2 1, 3 0, 1.5 -1.5, 0 0)) equals POLYGON((1 1 , 1 2, 2 2, 2 1, 3 0, 1.5 -1.5, 0 0, 1 1)).

• MULTILINESTRING((1 2, 4 3),(0 0, -1 -4)) equals MULTILINESTRING((0 0, -1 -4),(1 2, 4 3)).

Coordinates are stored as FLOAT types. Thus, rounding errors are expected when importing Well-Known Text (WKT) values because the limitations of floating-point number representation.

g1 and g2 must both be GEOMETRY objects or both be GEOGRAPHY objects. Also, g1 and g2 cannot both be of type GeometryCollection.

Behavior type

Syntax

ST_Equals( g1, g2 )

Arguments

g1

Spatial object to compare to g2, type GEOMETRY or GEOGRAPHY

g2

Spatial object to compare to g1, type GEOMETRY or GEOGRAPHY

Returns

BOOLEAN

Supported data types

Examples

The following examples show how to use ST_Equals.

Two linestrings:

=> SELECT ST_Equals (ST_GeomFromText('LINESTRING(-1 2, 0 3)'),
   ST_GeomFromText('LINESTRING(0 3, -1 2)'));
 ST_Equals
--------------
 t
(1 row)

Two polygons:

=> SELECT ST_Equals (ST_GeographyFromText('POLYGON((43.22 42.21,40.3 39.88,
   42.1 50.03,43.22 42.21))'),ST_GeographyFromText('POLYGON((43.22 42.21,
   40.3 39.88,42.1 50.31,43.22 42.21))'));
 ST_Equals
--------------
 f
(1 row)