postgis split polygons with polygons

postgis_split_polygons.sql

CREATE TABLE public.testpolygons1
(
  gid serial PRIMARY KEY,
  geom geometry(Polygon,3857)
);

CREATE TABLE public.testpolygons2
(
  gid serial PRIMARY KEY,
  geom geometry(Polygon,3857)
);


-- NOW DIGITIZE SOME POLYGONS so polygons in layer polygons1 contain polygons in layer polygons2;


-- NOW LOOP THROUGH all features from layer polygons1

DO 
$$
DECLARE
  query_string   TEXT;
  var_record RECORD;
  var_record2 RECORD;
  
BEGIN
  FOR var_record IN 
	SELECT gid, geom from testpolygons1
	 LOOP
    BEGIN
    IF(
    (select count(*) from (select var_record.gid from testpolygons2 as b where ST_Contains(var_record.geom, ST_Boundary(b.geom)) ) as test)>0 
    ) THEN
	INSERT INTO testpolygons1(geom)
	select (ST_Dump(ST_Split(var_record.geom,b.geom))).geom  -- ADD MORE ATTRIBUTES IF NEEDED
		from
		(SELECT ST_Boundary(geom) as geom from testpolygons2) as b
		WHERE ST_Contains(var_record.geom, b.geom)
		;
		DELETE FROM testpolygons1 where gid=var_record.gid;
	
RAISE NOTICE '%', var_record.geom;
  ELSE
RAISE NOTICE 'no need to split';
     END IF;

    EXCEPTION
      WHEN OTHERS THEN
        RAISE WARNING 'Error: %', SQLERRM;
    END;

  END LOOP;
END$$;


------------------

-- OR DO THE SAME WITH A FUNCTION:

CREATE FUNCTION poly_split_poly() RETURNS void AS $$

DECLARE
  var_record RECORD;
  
BEGIN
  FOR var_record IN 
	SELECT gid, geom from testpolygons1
	 LOOP
    BEGIN
    IF(
    (select count(*) from (select var_record.gid from testpolygons2 as b where ST_Contains(var_record.geom, ST_Boundary(b.geom)) ) as test)>0 
    ) THEN
	INSERT INTO testpolygons1(geom)
	select (ST_Dump(ST_Split(var_record.geom,b.geom))).geom  -- ADD MORE ATTRIBUTES IF NEEDED before insert
		from
		(SELECT ST_Boundary(geom) as geom from testpolygons2) as b
		WHERE ST_Contains(var_record.geom, b.geom)
		;
		DELETE FROM testpolygons1 where gid=var_record.gid;
	
--RAISE NOTICE '%', var_record.geom;
RAISE NOTICE 'Polygon with gid % splitted', var_record.gid;

  ELSE
RAISE NOTICE 'no need to split';
     END IF;

    EXCEPTION
      WHEN OTHERS THEN
        RAISE WARNING 'Error: %', SQLERRM;
    END;

  END LOOP;
   END;
$$ LANGUAGE plpgsql;

-- RUN THE FUNCTION:

select poly_split_poly();