ST_SYMDIFFERENCE()

All functions > GEOSPATIAL > ST_SYMDIFFERENCE()

Returns the geometry/geography representing the point set symmetric difference of two inputs (union minus intersection).

Signatures

Symmetric difference

Returns: Parts of A and B that do not overlap; sub kind depends on result shape

ST_SYMDIFFERENCE(geo1: T, geo2: T) → GEOMETRY or GEOGRAPHY

With:

• T : Custom types: GEOM_POINT | GEOM_LINESTRING | GEOM_POLYGON | GEOM_MULTIPOINT | GEOM_MULTILINESTRING | GEOM_MULTIPOLYGON | GEOM_MULTIANY | GEOG_POINT | GEOG_LINESTRING | GEOG_POLYGON | GEOG_MULTIPOINT | GEOG_MULTILINESTRING | GEOG_MULTIPOLYGON | GEOG_MULTIANY

Signature notes:

• Equivalent to ST_UNION(A, B) minus ST_INTERSECTION(A, B), or ST_UNION(ST_DIFFERENCE(A, B), ST_DIFFERENCE(B, A))
• Two disjoint geometries: returns their union
• Two identical geometries: returns an empty geometry
• Both inputs must be the same type family
• Returns NULL if either input is NULL

Examples

SELECT
    f1 := ST_ASTEXT(ST_SYMDIFFERENCE(ST_GEOMFROMTEXT('POLYGON ((0 0, 3 0, 3 3, 0 3, 0 0))'), ST_GEOMFROMTEXT('POLYGON ((2 2, 5 2, 5 5, 2 5, 2 2))'))) -- Non-overlapping parts of two partially overlapping squares (DuckDB: ST_Union of mutual ST_Difference; WKT ring order may differ from other engines)
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