rework postcode computation

Now adds areas to location_postcodes, ignores postcode points
inside areas and supports customizable extents.

lib-sql/functions/postcode_triggers.sql

@@ -2,10 +2,10 @@
 --
 -- This file is part of Nominatim. (https://nominatim.org)
 --
--- Copyright (C) 2022 by the Nominatim developer community.
+-- Copyright (C) 2025 by the Nominatim developer community.
 -- For a full list of authors see the git log.
 
--- Trigger functions for location_postcode table.
+-- Trigger functions for location_postcodes table.
 
 
 -- Trigger for updates of location_postcode
@@ -13,7 +13,7 @@
 -- Computes the parent object the postcode most likely refers to.
 -- This will be the place that determines the address displayed when
 -- searching for this postcode.
-CREATE OR REPLACE FUNCTION postcode_update()
+CREATE OR REPLACE FUNCTION postcodes_update()
   RETURNS TRIGGER
   AS $$
 DECLARE
@@ -28,13 +28,10 @@ BEGIN
 
     partition := get_partition(NEW.country_code);
 
-    SELECT * FROM get_postcode_rank(NEW.country_code, NEW.postcode)
-      INTO NEW.rank_search, NEW.rank_address;
-
     NEW.parent_place_id = 0;
     FOR location IN
       SELECT place_id
-        FROM getNearFeatures(partition, NEW.geometry, NEW.geometry, NEW.rank_search)
+        FROM getNearFeatures(partition, NEW.centroid, NEW.centroid, NEW.rank_search)
         WHERE NOT isguess ORDER BY rank_address DESC, distance asc LIMIT 1
     LOOP
         NEW.parent_place_id = location.place_id;
@@ -45,3 +42,89 @@ END;
 $$
 LANGUAGE plpgsql;
 
+
+CREATE OR REPLACE FUNCTION postcodes_delete()
+  RETURNS TRIGGER
+  AS $$
+BEGIN
+{% if not disable_diff_updates %}
+  UPDATE placex p SET indexed_status = 2
+   WHERE p.postcode = OLD.postcode AND ST_Intersects(OLD.geometry, p.geometry)
+         AND indexed_status = 0;
+{% endif %}
+
+  RETURN OLD;
+END;
+$$
+LANGUAGE plpgsql;
+
+
+CREATE OR REPLACE FUNCTION postcodes_insert()
+  RETURNS TRIGGER
+  AS $$
+DECLARE
+  existing RECORD;
+BEGIN
+  IF NEW.osm_id is not NULL THEN
+    -- postcode area, remove existing from same OSM object
+    SELECT * INTO existing FROM location_postcodes p
+      WHERE p.osm_id = NEW.osm_id;
+
+    IF existing.place_id is not NULL THEN
+      IF existing.postcode != NEW.postcode or existing.country_code != NEW.country_code THEN
+        DELETE FROM location_postcodes p WHERE p.osm_id = NEW.osm_id;
+        existing := NULL;
+      END IF;
+    END IF;
+  END IF;
+
+  IF existing is NULL THEN
+    SELECT * INTO existing FROM location_postcodes p
+      WHERE p.country_code = NEW.country_code AND p.postcode = NEW.postcode;
+
+    IF existing.postcode is NULL THEN
+{% if not disable_diff_updates %}
+      UPDATE placex p SET indexed_status = 2
+       WHERE ST_Intersects(NEW.geometry, p.geometry)
+             AND indexed_status = 0
+             AND p.rank_address >= 22 AND not p.address ? 'postcode';
+{% endif %}
+
+      -- new entry, just insert
+      NEW.indexed_status := 1;
+      NEW.place_id := nextval('seq_place');
+      RETURN NEW;
+    END IF;
+  END IF;
+
+  -- update: only when there are changes
+  IF coalesce(NEW.osm_id, -1) != coalesce(existing.osm_id, -1)
+     OR (NEW.osm_id is not null AND NEW.geometry::text != existing.geometry::text)
+     OR (NEW.osm_id is null
+         AND (abs(ST_X(existing.centroid) - ST_X(NEW.centroid)) > 0.0000001
+              OR abs(ST_Y(existing.centroid) - ST_Y(NEW.centroid)) > 0.0000001))
+  THEN
+{% if not disable_diff_updates %}
+    UPDATE placex p SET indexed_status = 2
+      WHERE ST_Intersects(ST_Difference(NEW.geometry, existing.geometry), p.geometry)
+            AND indexed_status = 0
+            AND p.rank_address >= 22 AND not p.address ? 'postcode';
+
+    UPDATE placex p SET indexed_status = 2
+      WHERE ST_Intersects(ST_Difference(existing.geometry, NEW.geometry), p.geometry)
+            AND indexed_status = 0
+            AND p.postcode = OLD.postcode;
+{% endif %}
+
+    UPDATE location_postcodes p
+      SET osm_id = NEW.osm_id,
+          indexed_status = 2,
+          centroid = NEW.centroid,
+          geometry = NEW.geometry
+      WHERE p.country_code = NEW.country_code AND p.postcode = NEW.postcode;
+  END IF;
+
+  RETURN NULL;
+END;
+$$
+LANGUAGE plpgsql;