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    ApsaraDB RDS:ST_SimplifyVW

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    ApsaraDB RDS:ST_SimplifyVW

    Last Updated:Mar 28, 2026

    ST_SimplifyVW returns a simplified version of the input geometry using the Visvalingam-Whyatt algorithm.

    Syntax

    geometry ST_SimplifyVW(geometry geomA, float tolerance);

    Parameters

    ParameterDescription
    geomAThe input geometry object to simplify.
    toleranceThe tolerance that you want to specify.

    Usage notes

    • Simplification applies to the component line and polygon elements of the input geometry. Use this function on any geometry type, including GeometryCollection — each element is simplified individually.

    • The supported multi-geometry types for direct simplification are MultiLineString, MultiPolygon, and MultiPoint.

    • The returned geometry may lose simplicity.

    • This function may produce invalid geometry by altering topology. To preserve topology and ensure validity, use ST_SimplifyPreserveTopology instead.

    • This function supports 3D geometry. The Z values of input vertices influence the simplification result.

    Examples

    The following example compares ST_Simplify (Douglas-Peucker algorithm) and ST_SimplifyVW (Visvalingam-Whyatt algorithm) on the same LINESTRING, both with a tolerance of 0.5.

    SELECT
  g,
  ST_Simplify(g, 0.5),
  ST_SimplifyVW(g, 0.5)
FROM (
  SELECT 'LINESTRING(0 0,2 2,3 1,3.5 1.5,5 0,5.25 0.25,5.5 0)'::geometry AS g
) AS t;

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