Better update of osm_important_waterway_linestring, use frist and last version of osm object (#997)

Current implementation of osm_important_waterway_linestring have two bugs:
* The distinct on is_old keep the oldest version of the old object, and the oldest version of the new object, but need the last version of the new object.
* Delete the old version of the object and rebuild the using the new version of the object. But we need to remove matchings the old and the new version of the object, then rebuild the two.

Then only delete and update using first and last version of the object, intermediate versions are ignored.

Similar implementation of what is done in #996.

layers/waterway/update_important_waterway.sql

@@ -79,25 +79,23 @@ CREATE SCHEMA IF NOT EXISTS waterway_important;
 CREATE TABLE IF NOT EXISTS waterway_important.changes
 (
     id serial PRIMARY KEY,
+    osm_id bigint,
     is_old boolean,
     name character varying,
     name_en character varying,
     name_de character varying,
-    tags hstore,
-    UNIQUE (is_old, name, name_en, name_de, tags)
+    tags hstore
 );
 CREATE OR REPLACE FUNCTION waterway_important.store() RETURNS trigger AS
 $$
 BEGIN
     IF (tg_op IN ('DELETE', 'UPDATE')) AND OLD.name <> '' AND OLD.waterway = 'river' THEN
         INSERT INTO waterway_important.changes(is_old, name, name_en, name_de, tags)
-        VALUES (TRUE, OLD.name, OLD.name_en, OLD.name_de, slice_language_tags(OLD.tags))
-        ON CONFLICT(is_old, name, name_en, name_de, tags) DO NOTHING;
+        VALUES (TRUE, OLD.name, OLD.name_en, OLD.name_de, slice_language_tags(OLD.tags));
     END IF;
     IF (tg_op IN ('UPDATE', 'INSERT')) AND NEW.name <> '' AND NEW.waterway = 'river' THEN
         INSERT INTO waterway_important.changes(is_old, name, name_en, name_de, tags)
-        VALUES (FALSE, NEW.name, NEW.name_en, NEW.name_de, slice_language_tags(NEW.tags))
-        ON CONFLICT(is_old, name, name_en, name_de, tags) DO NOTHING;
+        VALUES (FALSE, NEW.name, NEW.name_en, NEW.name_de, slice_language_tags(NEW.tags));
     END IF;
     RETURN NULL;
 END;
@@ -123,11 +121,34 @@ BEGIN
     RAISE LOG 'Refresh waterway';
 
     -- REFRESH osm_important_waterway_linestring
+
+    -- Compact the change history to keep only the first and last version, and then uniq version of row
+    CREATE TEMP TABLE changes_compact AS
+    SELECT DISTINCT ON (name, name_en, name_de, tags)
+        name,
+        name_en,
+        name_de,
+        tags
+    FROM ((
+              SELECT DISTINCT ON (osm_id) *
+              FROM waterway_important.changes
+              WHERE is_old
+              ORDER BY osm_id,
+                       id ASC
+          )
+          UNION ALL
+          (
+              SELECT DISTINCT ON (osm_id) *
+              FROM waterway_important.changes
+              WHERE NOT is_old
+              ORDER BY osm_id,
+                       id DESC
+          )) AS t;
+
     DELETE
     FROM osm_important_waterway_linestring AS w
-        USING waterway_important.changes AS c
-    WHERE c.is_old
-      AND w.name = c.name
+        USING changes_compact AS c
+    WHERE w.name = c.name
       AND w.name_en IS NOT DISTINCT FROM c.name_en
       AND w.name_de IS NOT DISTINCT FROM c.name_de
       AND w.tags IS NOT DISTINCT FROM c.tags;
@@ -145,23 +166,21 @@ BEGIN
                     w.name_de,
                     slice_language_tags(w.tags) AS tags
              FROM osm_waterway_linestring AS w
-                      JOIN waterway_important.changes AS c ON
+                      JOIN changes_compact AS c ON
                      w.name = c.name AND w.name_en IS NOT DISTINCT FROM c.name_en AND
                      w.name_de IS NOT DISTINCT FROM c.name_de AND
                      slice_language_tags(w.tags) IS NOT DISTINCT FROM c.tags
              WHERE w.name <> ''
                AND w.waterway = 'river'
                AND ST_IsValid(geometry)
-               AND NOT c.is_old
              GROUP BY w.name, w.name_en, w.name_de, slice_language_tags(w.tags)
          ) AS waterway_union;
 
     -- REFRESH sm_important_waterway_linestring_gen1
     DELETE
     FROM osm_important_waterway_linestring_gen1 AS w
-        USING waterway_important.changes AS c
-    WHERE c.is_old
-      AND w.name = c.name
+        USING changes_compact AS c
+    WHERE w.name = c.name
       AND w.name_en IS NOT DISTINCT FROM c.name_en
       AND w.name_de IS NOT DISTINCT FROM c.name_de
       AND w.tags IS NOT DISTINCT FROM c.tags;
@@ -169,15 +188,13 @@ BEGIN
     INSERT INTO osm_important_waterway_linestring_gen1
     SELECT w.*
     FROM osm_important_waterway_linestring_gen1_view AS w
-             NATURAL JOIN waterway_important.changes AS c
-    WHERE NOT c.is_old;
+             NATURAL JOIN changes_compact AS c;
 
     -- REFRESH osm_important_waterway_linestring_gen2
     DELETE
     FROM osm_important_waterway_linestring_gen2 AS w
-        USING waterway_important.changes AS c
-    WHERE c.is_old
-      AND w.name = c.name
+        USING changes_compact AS c
+    WHERE w.name = c.name
       AND w.name_en IS NOT DISTINCT FROM c.name_en
       AND w.name_de IS NOT DISTINCT FROM c.name_de
       AND w.tags IS NOT DISTINCT FROM c.tags;
@@ -185,15 +202,13 @@ BEGIN
     INSERT INTO osm_important_waterway_linestring_gen2
     SELECT w.*
     FROM osm_important_waterway_linestring_gen2_view AS w
-             NATURAL JOIN waterway_important.changes AS c
-    WHERE NOT c.is_old;
+             NATURAL JOIN changes_compact AS c;
 
     -- REFRESH osm_important_waterway_linestring_gen3
     DELETE
     FROM osm_important_waterway_linestring_gen3 AS w
-        USING waterway_important.changes AS c
-    WHERE c.is_old
-      AND w.name = c.name
+        USING changes_compact AS c
+    WHERE w.name = c.name
       AND w.name_en IS NOT DISTINCT FROM c.name_en
       AND w.name_de IS NOT DISTINCT FROM c.name_de
       AND w.tags IS NOT DISTINCT FROM c.tags;
@@ -201,9 +216,9 @@ BEGIN
     INSERT INTO osm_important_waterway_linestring_gen3
     SELECT w.*
     FROM osm_important_waterway_linestring_gen3_view AS w
-             NATURAL JOIN waterway_important.changes AS c
-    WHERE NOT c.is_old;
+             NATURAL JOIN changes_compact AS c;
 
+    DROP TABLE changes_compact;
     -- noinspection SqlWithoutWhere
     DELETE FROM waterway_important.changes;
     -- noinspection SqlWithoutWhere