Add fallback search mechanism for dropped databases lookup

lib-sql/tiger_import_start.sql

@@ -15,6 +15,99 @@ CREATE TABLE location_property_tiger_import (
   step SMALLINT,
   postcode TEXT);
 
+
+-- Lookup functions for tiger import when update 
+-- informations are dropped (see gh-issue #2463)
+CREATE OR REPLACE FUNCTION getNearestNamedRoadPlaceIdSlow(in_centroid GEOMETRY,
+                                                      in_token_info JSONB)
+  RETURNS BIGINT
+  AS $$
+DECLARE
+  out_place_id BIGINT;
+
+BEGIN
+  SELECT place_id INTO out_place_id 
+    FROM search_name
+    WHERE 
+        -- finds rows where name_vector shares elements with search tokens.
+        token_matches_street(in_token_info, name_vector)
+        -- limits search area
+        AND centroid && ST_Expand(in_centroid, 0.015) 
+        AND address_rank BETWEEN 26 AND 27
+    ORDER BY ST_Distance(centroid, in_centroid) ASC 
+    LIMIT 1;
+
+  RETURN out_place_id;
+END
+$$
+LANGUAGE plpgsql;
+
+
+CREATE OR REPLACE FUNCTION getNearestParallelRoadFeatureSlow(line GEOMETRY)
+  RETURNS BIGINT
+  AS $$
+DECLARE
+  r RECORD;
+  search_diameter FLOAT;
+  p1 GEOMETRY;
+  p2 GEOMETRY;
+  p3 GEOMETRY;
+
+BEGIN
+  IF ST_GeometryType(line) not in ('ST_LineString') THEN
+    RETURN NULL;
+  END IF;
+
+  p1 := ST_LineInterpolatePoint(line,0);
+  p2 := ST_LineInterpolatePoint(line,0.5);
+  p3 := ST_LineInterpolatePoint(line,1);
+
+    search_diameter := 0.0005;
+    WHILE search_diameter < 0.01 LOOP
+      FOR r IN
+        SELECT place_id FROM placex
+          WHERE ST_DWithin(line, geometry, search_diameter)
+          AND rank_address BETWEEN 26 AND 27
+          ORDER BY (ST_distance(geometry, p1)+
+                    ST_distance(geometry, p2)+
+                    ST_distance(geometry, p3)) ASC limit 1
+      LOOP
+        RETURN r.place_id;
+      END LOOP;
+      search_diameter := search_diameter * 2;
+    END LOOP;
+    RETURN NULL;
+END
+$$
+LANGUAGE plpgsql;
+
+
+CREATE OR REPLACE FUNCTION getNearestRoadPlaceIdSlow(point GEOMETRY)
+  RETURNS BIGINT
+  AS $$
+DECLARE
+  r RECORD;
+  search_diameter FLOAT;
+BEGIN
+    search_diameter := 0.00005;
+    WHILE search_diameter < 0.1 LOOP
+      FOR r IN
+        SELECT place_id FROM placex
+          WHERE ST_DWithin(geometry, point, search_diameter)
+          AND rank_address BETWEEN 26 AND 27
+          ORDER BY ST_Distance(geometry, point) ASC limit 1
+      LOOP
+        RETURN r.place_id;
+      END LOOP;
+      search_diameter := search_diameter * 2;
+    END LOOP;
+    RETURN NULL;
+END
+$$
+LANGUAGE plpgsql;
+
+
+-- Tiger import function
 CREATE OR REPLACE FUNCTION tiger_line_import(linegeo GEOMETRY, in_startnumber INTEGER,
                                              in_endnumber INTEGER, interpolationtype TEXT,
                                              token_info JSONB, in_postcode TEXT) RETURNS INTEGER
@@ -71,28 +164,50 @@ BEGIN
   place_centroid := ST_Centroid(linegeo);
   out_partition := get_partition('us');
 
-  out_parent_place_id := getNearestNamedRoadPlaceId(out_partition, place_centroid,
+  -- HYBRID LOOKUP LOGIC (see gh-issue #2463)
+  -- if partition tables exist, use them for fast spatial lookups
+  {% if 'location_road_0' in db.tables %}
+    out_parent_place_id := getNearestNamedRoadPlaceId(out_partition, place_centroid,
                                                     token_info);
 
-  IF out_parent_place_id IS NULL THEN
-    SELECT getNearestParallelRoadFeature(out_partition, linegeo)
-      INTO out_parent_place_id;
+    IF out_parent_place_id IS NULL THEN
+      SELECT getNearestParallelRoadFeature(out_partition, linegeo)
+        INTO out_parent_place_id;
+    END IF;
+
+    IF out_parent_place_id IS NULL THEN
+      SELECT getNearestRoadPlaceId(out_partition, place_centroid)
+        INTO out_parent_place_id;
+    END IF;
+
+  -- When updatable information has been dropped:
+  -- Partition tables no longer exist, but search_name still persists.
+  {% elif 'search_name' in db.tables %}
+    -- Fallback: Look up in 'search_name' table 
+    -- though spatial lookups here can be slower.
+    out_parent_place_id := getNearestNamedRoadPlaceIdSlow(place_centroid, token_info);
+
+    IF out_parent_place_id IS NULL THEN
+      out_parent_place_id := getNearestParallelRoadFeatureSlow(linegeo);
+    END IF;
+
+    IF out_parent_place_id IS NULL THEN
+      out_parent_place_id := getNearestRoadPlaceIdSlow(place_centroid);
+    END IF;
+  {% endif %}
+
+  -- If parent was found, insert street(line) into import table
+  IF out_parent_place_id IS NOT NULL THEN
+    INSERT INTO location_property_tiger_import (linegeo, place_id, partition,
+                                                parent_place_id, startnumber, endnumber,
+                                                step, postcode)
+    VALUES (linegeo, nextval('seq_place'), out_partition,
+            out_parent_place_id, startnumber, endnumber,
+            stepsize, in_postcode);
+
+    RETURN 1;
   END IF;
 
-  IF out_parent_place_id IS NULL THEN
-    SELECT getNearestRoadPlaceId(out_partition, place_centroid)
-      INTO out_parent_place_id;
-  END IF;
-
---insert street(line) into import table
-insert into location_property_tiger_import (linegeo, place_id, partition,
-                                            parent_place_id, startnumber, endnumber,
-                                            step, postcode)
-values (linegeo, nextval('seq_place'), out_partition,
-        out_parent_place_id, startnumber, endnumber,
-        stepsize, in_postcode);
-
-  RETURN 1;
 END;
 $$
 LANGUAGE plpgsql;