Use custom enum type

layers/place/city.sql

@@ -1,13 +1,13 @@
 CREATE OR REPLACE FUNCTION layer_city(bbox geometry, zoom_level int, pixel_width numeric)
 RETURNS TABLE(osm_id bigint, geometry geometry, name text, name_en text, place text, scalerank int) AS $$
-    SELECT osm_id, geometry, name, name_en, place, scalerank
+    SELECT osm_id, geometry, name, name_en, place::text, scalerank
     FROM osm_place_point
     WHERE geometry && bbox
       AND ((zoom_level = 2 AND scalerank = 0)
         OR (zoom_level BETWEEN 3 AND 7 AND scalerank < zoom_level)
       )
     UNION ALL
-    SELECT osm_id, geometry, name, name_en, place, scalerank FROM (
+    SELECT osm_id, geometry, name, name_en, place::text, scalerank FROM (
         SELECT osm_id, geometry, name, name_en, place, scalerank,
 			row_number() OVER (
 				PARTITION BY LabelGrid(geometry, 150 * pixel_width)

layers/place/types.sql

@@ -5,3 +5,5 @@ BEGIN
     END IF;
 END
 $$;
+
+ALTER TABLE osm_place_point ALTER COLUMN place TYPE place_subclass USING place::place_subclass;