Clean update_route_member.sql (#981)

Clean and do refactoring on `update_route_member.sql` as first step to replace materialized view osm_transportation_name_network by tables with diff update. See #892.

layers/transportation_name/update_route_member.sql

@@ -1,13 +1,12 @@
-DROP TRIGGER IF EXISTS trigger_flag_transportation_name ON osm_route_member;
+CREATE TABLE IF NOT EXISTS ne_10m_admin_0_bg_buffer AS
-
+SELECT ST_Buffer(geometry, 10000)
+FROM ne_10m_admin_0_countries
+WHERE iso_a2 = 'GB';
 
 -- create GBR relations (so we can use it in the same way as other relations)
 CREATE OR REPLACE FUNCTION update_gbr_route_members() RETURNS void AS
 $$
-DECLARE
-    gbr_geom geometry;
 BEGIN
-    SELECT st_buffer(geometry, 10000) INTO gbr_geom FROM ne_10m_admin_0_countries WHERE iso_a2 = 'GB';
     DELETE FROM osm_route_member WHERE network IN ('omt-gb-motorway', 'omt-gb-trunk');
 
     INSERT INTO osm_route_member (osm_id, member, ref, network)
@@ -17,22 +16,15 @@ BEGIN
            CASE WHEN highway = 'motorway' THEN 'omt-gb-motorway' ELSE 'omt-gb-trunk' END
     FROM osm_highway_linestring
     WHERE length(ref) > 0
-      AND ST_Intersects(geometry, gbr_geom)
+      AND ST_Intersects(geometry, (SELECT * FROM ne_10m_admin_0_bg_buffer))
       AND highway IN ('motorway', 'trunk');
 END;
 $$ LANGUAGE plpgsql;
 
 
--- etldoc:  osm_route_member ->  osm_route_member
+CREATE OR REPLACE FUNCTION osm_route_member_network_type(network text, name text, ref text) RETURNS route_network_type AS
-CREATE OR REPLACE FUNCTION update_osm_route_member() RETURNS void AS
 $$
-BEGIN
+SELECT CASE
-    PERFORM update_gbr_route_members();
-
-    -- see http://wiki.openstreetmap.org/wiki/Relation:route#Road_routes
-    UPDATE osm_route_member
-    SET network_type =
-            CASE
            WHEN network = 'US:I' THEN 'us-interstate'::route_network_type
            WHEN network = 'US:US' THEN 'us-highway'::route_network_type
            WHEN network LIKE 'US:__' THEN 'us-state'::route_network_type
@@ -56,6 +48,18 @@ BEGIN
            WHEN network = 'omt-gb-motorway' THEN 'gb-motorway'::route_network_type
            WHEN network = 'omt-gb-trunk' THEN 'gb-trunk'::route_network_type
            END;
+$$ LANGUAGE sql IMMUTABLE
+                PARALLEL SAFE;
+
+-- etldoc:  osm_route_member ->  osm_route_member
+CREATE OR REPLACE FUNCTION update_osm_route_member() RETURNS void AS
+$$
+BEGIN
+    PERFORM update_gbr_route_members();
+
+    -- see http://wiki.openstreetmap.org/wiki/Relation:route#Road_routes
+    UPDATE osm_route_member
+    SET network_type = osm_route_member_network_type(network, name, ref);
 
 END;
 $$ LANGUAGE plpgsql;