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Snaps the vertices and segments of the input geometry to reference geometry within the specified tolerance distance. The tolerance parameter controls the maximum snap distance. If the minimum distance between the geometries exceeds the tolerance, the input geometry is returned unmodified. Adjusting the tolerance value allows tuning which vertices should snap to the reference and which remain untouched.

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Return type

The resulting geometry.

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Example

SELECT
    ST_Snap(poly, line, ST_Distance(poly, line) * 1.01) AS polySnapped FROM (
        SELECT ST_GeomFromWKT('POLYGON ((236877.58 -6.61, 236878.29 -8.35, 236879.98 -8.33, 236879.72 -7.63, 236880.35 -6.62, 236877.58 -6.61), (236878.45 -7.01, 236878.43 -7.52, 236879.29 -7.50, 236878.63 -7.22, 236878.76 -6.89, 236878.45 -7.01))') as poly,
            ST_GeomFromWKT('LINESTRING (236880.53 -8.22, 236881.15 -7.68, 236880.69 -6.81)') as line
)
ST_Snap applied example 
POLYGON ((236877.58 -6.61, 236878.29 -8.35, 236879.98 -8.33, 236879.72 -7.63, 236880.69 -6.81, 236877.58 -6.61), (236878.45 -7.01, 236878.43 -7.52, 236879.29 -7.5, 236878.63 -7.22, 236878.76 -6.89, 236878.45 -7.01))