CREATE FUNCTION "URX_PUBLIC"."_add_raster_constraint_pixel_types"(rastschema name, rasttable name, rastcolumn name) 
 RETURNS boolean AS 
$BODY$
	DECLARE
		fqtn text;
		cn name;
		sql text;
		attr text[];
		max int;
	BEGIN
		fqtn := '';
		IF length($1) > 0 THEN
			fqtn := quote_ident($1) || '.';
		END IF;
		fqtn := fqtn || quote_ident($2);

		cn := 'enforce_pixel_types_' || $3;

		sql := 'SELECT "URX_PUBLIC"._raster_constraint_pixel_types(' || quote_ident($3)
			|| ') FROM ' || fqtn
			|| ' LIMIT 1';
		BEGIN
			EXECUTE sql INTO attr;
		EXCEPTION WHEN OTHERS THEN
			RAISE NOTICE 'Unable to get the pixel types of a sample raster: % (%)',
        SQLERRM, SQLSTATE;
			RETURN FALSE;
		END;
		max := array_length(attr, 1);
		IF max < 1 OR max IS NULL THEN
			RAISE NOTICE 'Unable to get the pixel types of a sample raster (max < 1 or null)';
			RETURN FALSE;
		END IF;

		sql := 'ALTER TABLE ' || fqtn
			|| ' ADD CONSTRAINT ' || quote_ident(cn)
			|| ' CHECK (_raster_constraint_pixel_types(' || quote_ident($3)
			|| ') = ''{';
		FOR x in 1..max LOOP
			sql := sql || '"' || attr[x] || '"';
			IF x < max THEN
				sql := sql || ',';
			END IF;
		END LOOP;
		sql := sql || '}''::text[])';

		RETURN  "URX_PUBLIC"._add_raster_constraint(cn, sql);
	END;
	$BODY$
 LANGUAGE 'plpgsql' VOLATILESTRICT ;