Add highway names

layers/highway_name/layer.sql

@@ -0,0 +1,15 @@
+CREATE OR REPLACE FUNCTION layer_highway_name(bbox geometry, zoom_level integer)
+RETURNS TABLE(osm_id bigint, geometry geometry, name text, class highway_class, subclass text) AS $$
+    SELECT osm_id, geometry, name, to_highway_class(highway) AS class, highway AS subclass FROM (
+        SELECT * FROM osm_highway_name_linestring
+        WHERE zoom_level = 12 AND to_highway_class(highway) < 'minor_road'::highway_class AND NOT highway_is_link(highway)
+        UNION ALL
+        SELECT * FROM osm_highway_name_linestring
+        WHERE zoom_level = 13 AND to_highway_class(highway) < 'path'::highway_class
+        UNION ALL
+        SELECT * FROM osm_highway_name_linestring
+        WHERE zoom_level >= 14
+    ) AS zoom_levels
+    WHERE geometry && bbox
+    ORDER BY z_order ASC;
+$$ LANGUAGE SQL IMMUTABLE;