Group roads by type

osm2vectortiles.tm2source/data.yml

@@ -349,7 +349,7 @@ Layer:
           road_class(type, service, access) AS class, road_oneway(oneway) AS oneway, structure
           FROM (
             SELECT MAX(osm_id) AS osm_id, ST_Collect(geometry) AS geometry,
-                   NULL as type, NULL as construction, NULL as tracktype,
+                   type, NULL as construction, NULL as tracktype,
                    NULL as service, NULL as access,
                    0 as oneway, NULL AS structure, 0 AS z_order
             FROM (
@@ -359,6 +359,7 @@ Layer:
                 SELECT * FROM road_z6toz7
                 WHERE z(!scale_denominator!) BETWEEN 6 AND 7
             ) AS road_grouped_zoom_levels
+            GROUP BY type
             UNION ALL
             SELECT * FROM road_z8toz9
             WHERE z(!scale_denominator!) BETWEEN 8 AND 9