STContainsgeomA

STContainsgeomA is a naming convention used in some geographic information system contexts to refer to a spatial predicate that tests whether a geometry, often designated as geomA, contains another geometry. In standard spatial SQL, the analogous predicate is ST_Contains, typically invoked as ST_Contains(geomA, geomB). The variant name emphasizes geomA as the first argument or the primary geometry in the containment check.

Semantics of the predicate follow the conventional containment relationship defined in the DE-9IM model. It returns a boolean indicating whether geometry B lies entirely within geometry A, with the usual interpretation that B does not lie outside A’s boundary. In practice, the exact treatment of boundary-touching cases can depend on the specific spatial library or dialect, but the general idea is that A spatially contains B.

Usage and examples. The predicate is commonly employed in queries that require filtering by spatial relationships, such as selecting features whose geometry contains a given area or line. For example, in SQL-like syntax, a call such as STContainsgeomA(geomA, geomB) would return true for rows where geomA contains geomB, enabling spatial joins, topological validations, or geofencing logic. In many systems, STContainsgeomA is implemented as a wrapper or alias around ST_Contains with the first argument fixed to the geomA column or parameter.

Considerations. Ensure both geometries use the same coordinate reference system, and be mindful of empty or null geometries, which may yield non-intuitive results depending on the implementation. Performance often benefits from spatial indexing and proper SRID alignment.

Related concepts include ST_Contains, ST_Within, ST_Covers, and ST_CoveredBy, which express related spatial relationships and are commonly used together in geospatial queries.