A is fully within geography B using S2 spherical boolean operations. Returns true when every point of A’s interior lies in B’s interior. By OGC convention, ST_Within(A, B) is equivalent to ST_Contains(B, A), and shares the same boundary semantics.
Boundary semantics on the sphere are inherited from S2’s boolean operations and depend on each ring’s vertex orientation: along an edge that is “owned” by B’s boundary the test returns true, and along the opposite edge it returns false. Do not rely on a specific result for points that lie exactly on B’s boundary; for predictable behavior, use a strict interior point or expand B slightly with ST_Buffer before testing.
Signatures
Parameters
Geography
required
The geography tested for being within B.
Geography
required
The containing geography.
Return type
true if A is fully within B.