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ST_COVERS ​

Returns TRUE if every point in GEOGRAPHY B lies inside (intersects the interior or boundary of) GEOGRAPHY A. In other words, it ensures that no point of B lies in the exterior of A.

This function has the following properties:

  • Reflexive: Every GEOGRAPHY object covers itself
  • Antisymmetric: If ST_COVERS(A, B) = TRUE and ST_COVERS(B, A) = TRUE, then A and B are topologically equal
  • Converse of ST_COVEREDBY: ST_COVERS(A, B) = ST_COVEREDBY(B, A)

Generally, this function should be used instead of ST_CONTAINS because it has a simpler definition that does not require the interiors to intersect.

See also:

Syntax ​

sql
ST_COVERS(<a>, <b>)

Arguments ​

  • <a> and <b>: The GEOGRAPHY objects to check for a covers relationship

Returns ​

Returns TRUE if <a> covers <b>, otherwise returns FALSE

Example ​

sql
SELECT ST_COVERS('POLYGON((0 0, 0 2, 2 2, 2 0, 0 0))'::GEOGRAPHY, 'POINT(1 1)'::GEOGRAPHY);
-- TRUE

SELECT ST_COVERS('POLYGON((0 0, 0 2, 2 2, 2 0, 0 0))'::GEOGRAPHY, 'POINT(3 3)'::GEOGRAPHY);
-- FALSE