From dcfcd21c9609a83dc03606701a49aaf835c6dde5 Mon Sep 17 00:00:00 2001
From: Paul Bienkowski <pb@opatut.de>
Date: Tue, 26 Jul 2022 08:51:59 +0200
Subject: [PATCH] Emit all roads in obs_roads layer regardless of filter,
 generate only their statistics with filters

---
 tile-generator/layers/obs_roads/layer.sql | 61 +++++++++++++++++++----
 1 file changed, 50 insertions(+), 11 deletions(-)

diff --git a/tile-generator/layers/obs_roads/layer.sql b/tile-generator/layers/obs_roads/layer.sql
index 4521a66..2073150 100644
--- a/tile-generator/layers/obs_roads/layer.sql
+++ b/tile-generator/layers/obs_roads/layer.sql
@@ -20,12 +20,13 @@ RETURNS TABLE(
     SELECT
       road.way_id::bigint as way_id,
       road.geometry as geometry,
-      avg(distance_overtaker) as distance_overtaker_mean,
-      min(distance_overtaker) as distance_overtaker_min,
-      max(distance_overtaker) as distance_overtaker_max,
-      PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY distance_overtaker) as distance_overtaker_median,
-      array_agg(distance_overtaker) as distance_overtaker_array,
-      count(overtaking_event.id)::int as distance_overtaker_count,
+      e.distance_overtaker_mean,
+      e.distance_overtaker_min,
+      e.distance_overtaker_max,
+      e.distance_overtaker_median,
+      e.distance_overtaker_array,
+      e.distance_overtaker_count,
+      -- Since this is just one field we can subquery directly inline
       (
         SELECT count(road_usage.id) from road_usage
         JOIN track ON track.id = road_usage.track_id
@@ -36,14 +37,52 @@ RETURNS TABLE(
       ) as usage_count,
       r.dir as direction,
       road.zone::zone_type as zone,
+      -- Generate the "offset" column to be 0 for undirectional roads
       case when road.directionality = 0 then r.dir else 0 end as offset_direction
     FROM road
+
+    -- This JOIN duplicates directional roads with r.reversed set to TRUE and
+    -- FALSE, but keeps undirectional roads single.
     LEFT JOIN (VALUES (-1, TRUE), (1, FALSE), (0, FALSE)) AS r(dir, rev) ON (abs(r.dir) != road.directionality)
-    FULL OUTER JOIN overtaking_event ON (road.way_id = overtaking_event.way_id and (road.directionality != 0 or overtaking_event.direction_reversed = r.rev))
-      JOIN track ON overtaking_event.track_id = track.id
+
+    -- instead of a subquery, we join in a table that gives us overtaking
+    -- statistics by way_id, filtered by user_id and time
+    LEFT JOIN (
+        SELECT
+          overtaking_event.way_id as way_id,
+          overtaking_event.direction_reversed as direction_reversed,
+          avg(overtaking_event.distance_overtaker) as distance_overtaker_mean,
+          min(overtaking_event.distance_overtaker) as distance_overtaker_min,
+          max(overtaking_event.distance_overtaker) as distance_overtaker_max,
+          -- complicated way of saying "median" :)
+          PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY overtaking_event.distance_overtaker) as distance_overtaker_median,
+          -- get all single values as well
+          array_agg(overtaking_event.distance_overtaker) as distance_overtaker_array,
+          count(overtaking_event.id)::int as distance_overtaker_count
+        FROM overtaking_event
+        JOIN track ON track.id = overtaking_event.track_id
+        WHERE (user_id is NULL or track.author_id = user_id)
+          AND overtaking_event.time BETWEEN COALESCE(min_time, '1900-01-01'::timestamp) AND COALESCE(max_time, '2100-01-01'::timestamp)
+        GROUP BY overtaking_event.way_id, overtaking_event.direction_reversed
+    ) e on (e.way_id = road.way_id and (road.directionality != 0 or e.direction_reversed = r.rev))
+
     WHERE road.geometry && bbox
-      AND (user_id is NULL or user_id = track.author_id)
-      AND overtaking_event.time BETWEEN COALESCE(min_time, '1900-01-01'::timestamp) AND COALESCE(max_time, '2100-01-01'::timestamp)
-    GROUP BY road.name, road.way_id, road.geometry, road.directionality, road.zone, r.dir, r.rev;
+    GROUP BY
+      road.name,
+      road.way_id,
+      road.geometry,
+      road.directionality,
+      road.zone,
+      r.dir,
+      r.rev,
+      e.way_id,
+      e.direction_reversed,
+      e.distance_overtaker_mean,
+      e.distance_overtaker_min,
+      e.distance_overtaker_max,
+      e.distance_overtaker_median,
+      e.distance_overtaker_array,
+      e.distance_overtaker_count
+    ;
 
 $$ LANGUAGE SQL IMMUTABLE;