Optimize signals table and related materialized views (#146)

import/docker-startup.sh

@@ -131,5 +131,5 @@ $PSQL --tuples-only -c "with bounds as (SELECT st_transform(st_setsrid(ST_Extent
 echo "Import bounds: $(cat /data/import/bounds.json)"
 
 echo "Database summary"
-$PSQL -c "select table_name as table, pg_size_pretty(pg_total_relation_size(quote_ident(table_name))) as size from information_schema.tables where table_schema = 'public' order by table_name;"
-$PSQL -c "select pg_size_pretty(sum(pg_total_relation_size(quote_ident(table_name)))) as total_size from information_schema.tables where table_schema = 'public';"
+$PSQL -c "select concat(relname, ' (', relkind ,')') as name, pg_size_pretty(pg_table_size(oid)) as size from pg_class where relkind in ('m', 'r', 'i') and relname not like 'pg_%' order by pg_table_size(oid) desc;"
+$PSQL -c "select pg_size_pretty(SUM(pg_table_size(oid))) as size from pg_class where relkind in ('m', 'r', 'i') and relname not like 'pg_%';"

import/openrailwaymap.lua

@@ -228,6 +228,8 @@ local signals = osm2pgsql.define_table({
   name = 'signals',
   ids = { type = 'node', id_column = 'osm_id' },
   columns = signal_columns,
+  -- The queried table is signals_with_azimuth
+  cluster = 'no',
 })
 
 local boxes = osm2pgsql.define_table({

import/sql/signals_with_azimuth.sql.js

@@ -73,14 +73,18 @@ CREATE OR REPLACE VIEW signals_with_azimuth_view AS
   ) as sl ON true
   WHERE
     (railway IN ('signal', 'buffer_stop') AND signal_direction IS NOT NULL)
-    OR railway IN ('derail', 'vacancy_detection');
+      OR railway IN ('derail', 'vacancy_detection');
 
 -- Use the view directly such that the query in the view can be updated
 CREATE MATERIALIZED VIEW IF NOT EXISTS signals_with_azimuth AS
   SELECT
     *
   FROM
-    signals_with_azimuth_view;
+    signals_with_azimuth_view
+  WHERE
+    signal_feature IS NOT NULL 
+      OR speed_feature IS NOT NULL 
+      OR electrification_feature IS NOT NULL;
 
 CREATE INDEX IF NOT EXISTS signals_with_azimuth_geom_index
   ON signals_with_azimuth

import/sql/tile_views.sql

@@ -281,7 +281,7 @@ CREATE OR REPLACE VIEW speed_railway_signals AS
     speed_feature_type as type,
     azimuth,
     (signal_direction = 'both') as direction_both
-  FROM signals_with_azimuth s
+  FROM signals_with_azimuth
   WHERE railway = 'signal'
     AND speed_feature IS NOT NULL
   ORDER BY