Make sure at least very basic motorway junctions are shown

osm2vectortiles.tm2source/data.yml

@@ -955,12 +955,9 @@ Layer:
           name,
           NULLIF(ref, '') AS ref,
           NULLIF(char_length(ref), 0) AS reflen,
-          type,
-          road_class(type, NULL, NULL) AS class
+          junction_type(type) AS type,
+          road_type_class(junction_type(type)) AS class
           FROM (
-            SELECT * FROM motorway_junction_z11
-            WHERE z(!scale_denominator!) = 11
-            UNION ALL
             SELECT * FROM motorway_junction_z12toz14
             WHERE z(!scale_denominator!) BETWEEN 12 AND 14
           ) AS t

src/import-osm/mapping.yml

@@ -490,6 +490,12 @@ tables:
     - name: name
       key: name
       type: string
+    mapping:
+      highway:
+      - motorway_junction
+    filters:
+      exclude_tags:
+      - [ "ref", "__nil__" ]
   road_geometry:
     type: geometry
     fields:

src/import-sql/layers/motorway_junction.sql

@@ -1,9 +1,13 @@
-CREATE OR REPLACE VIEW motorway_junction_z11 AS
-    SELECT id AS osm_id, type, ref, name, geometry
-    FROM osm_motorway_junction_point
-    WHERE ref <> '' AND type <> 'trunk';
-
 CREATE OR REPLACE VIEW motorway_junction_z12toz14 AS
     SELECT id AS osm_id, type, ref, name, geometry
-    FROM osm_motorway_junction_point
-    WHERE ref <> '';
+    FROM osm_motorway_junction_point;
+
+CREATE OR REPLACE FUNCTION junction_type(type VARCHAR) RETURNS VARCHAR
+AS $$
+BEGIN
+    RETURN CASE
+        WHEN type = 'motorway_junction' THEN 'motorway'
+        ELSE type
+    END;
+END;
+$$ LANGUAGE plpgsql IMMUTABLE;