Fix SQL update logic (patch from 3.6.2)

layers/water_name/update_water_lakeline.sql

@@ -0,0 +1,52 @@
+DROP TRIGGER IF EXISTS trigger_flag_line ON osm_water_polygon;
+DROP TRIGGER IF EXISTS trigger_refresh ON water_lakeline.updates;
+
+-- etldoc:  osm_water_polygon ->  osm_water_lakeline
+-- etldoc:  lake_centerline  ->  osm_water_lakeline
+DROP MATERIALIZED VIEW IF EXISTS osm_water_lakeline CASCADE;
+
+CREATE MATERIALIZED VIEW osm_water_lakeline AS (
+	SELECT wp.osm_id,
+		ll.wkb_geometry AS geometry,
+		name, name_en, name_de,
+		slice_language_tags(tags) || get_basic_names(tags, ll.wkb_geometry) AS tags,
+		ST_Area(wp.geometry) AS area
+    FROM osm_water_polygon AS wp
+    INNER JOIN lake_centerline ll ON wp.osm_id = ll.osm_id
+    WHERE wp.name <> ''
+);
+CREATE INDEX IF NOT EXISTS osm_water_lakeline_geometry_idx ON osm_water_lakeline USING gist(geometry);
+
+-- Handle updates
+
+CREATE SCHEMA IF NOT EXISTS water_lakeline;
+
+CREATE TABLE IF NOT EXISTS water_lakeline.updates(id serial primary key, t text, unique (t));
+CREATE OR REPLACE FUNCTION water_lakeline.flag() RETURNS trigger AS $$
+BEGIN
+    INSERT INTO water_lakeline.updates(t) VALUES ('y')  ON CONFLICT(t) DO NOTHING;
+    RETURN null;
+END;
+$$ language plpgsql;
+
+CREATE OR REPLACE FUNCTION water_lakeline.refresh() RETURNS trigger AS
+  $BODY$
+  BEGIN
+    RAISE LOG 'Refresh water_lakeline';
+    REFRESH MATERIALIZED VIEW osm_water_lakeline;
+    DELETE FROM water_lakeline.updates;
+    RETURN null;
+  END;
+  $BODY$
+language plpgsql;
+
+CREATE TRIGGER trigger_flag_line
+    AFTER INSERT OR UPDATE OR DELETE ON osm_water_polygon
+    FOR EACH STATEMENT
+    EXECUTE PROCEDURE water_lakeline.flag();
+
+CREATE CONSTRAINT TRIGGER trigger_refresh
+    AFTER INSERT ON water_lakeline.updates
+    INITIALLY DEFERRED
+    FOR EACH ROW
+    EXECUTE PROCEDURE water_lakeline.refresh();