ST_ConcaveHull

Introduction: Return the Concave Hull of polygon A, with alpha set to pctConvex[0, 1] in the Delaunay Triangulation method, the concave hull will not contain a hole unless allowHoles is set to true

Format: ST_ConcaveHull (A:geometry, pctConvex:float)

Format: ST_ConcaveHull (A:geometry, pctConvex:float, allowHoles:Boolean)

SQL example:

SELECT ST_ConcaveHull(polygondf.countyshape, pctConvex)`
FROM polygondf