ST_ForceSFS

What is ST_ForceSFS?

ST_ForceSFS converts an input to a geometry compatible with the OGC Simple Features Specification (SFS) — stripping curve types such as CIRCULARSTRING, COMPOUNDCURVE, or CURVEPOLYGON and (optionally) pinning to a specific SFS version.

1ST_ForceSFS(geometry geom) → geometry
2ST_ForceSFS(geometry geom, text version) → geometry

The two-argument form accepts an SFS version string such as '1.1'. Curves are linearised using default tolerance. Available since PostGIS 3.1.

When would you use ST_ForceSFS?

Use ST_ForceSFS when interoperating with strict SFS-compliant clients — some desktop GIS packages, older JDBC drivers, and Java-based spatial engines choke on curve geometry. Forcing SFS before export ensures the feature stream matches what the consumer can parse.

It is also a defensive pre-step in CI pipelines that emit shapefile, KML, or plain WKT output, where curves and higher-dimensional coordinates should be explicitly downcast rather than silently dropped.

FAQs

Does ST_ForceSFS change dimensionality?

It may, depending on version — the SFS 1.1 profile is 2D only, so Z/M ordinates are stripped when version = '1.1' is specified.

How are curves linearised?

Via the default ST_CurveToLine tolerance. For precise control, call ST_CurveToLine explicitly first with tuned tolerance parameters.

What version was ST_ForceSFS introduced?

PostGIS 3.1.

Is ST_ForceSFS idempotent on SFS-compliant input?

Yes — already-compliant geometry is returned unchanged.