ST_RemovingHolesInPolygonsByArea

DROP FUNCTION IF EXISTS ST_RemovingHolesInPolygonsByArea(
    geom GEOMETRY,
    area real)

CREATE OR REPLACE FUNCTION ST_RemovingHolesInPolygonsByArea(
    geom GEOMETRY,
    area real)
RETURNS GEOMETRY AS
$BODY$
    WITH
         tbla AS (SELECT (ST_Dump($1)).geom)
                  SELECT ST_Collect(ARRAY(SELECT ST_MakePolygon(ST_ExteriorRing(geom), ARRAY(SELECT ST_ExteriorRing(rings.geom) FROM ST_DumpRings(geom) AS rings WHERE rings.path[1]>0 AND ST_Area(rings.geom)>=area)) FROM ST_Dump(geom))) AS geom FROM tbla;
$BODY$
LANGUAGE SQL

SELECT ST_RemovingHolesInPolygonsByArea(geom, 100) geom FROM <geodata>

The authors and developers of the function body is
© Martin Davis https://github.com/dr-jts