Incremental update marine point (#952)

Replacing update on the whole table with an update only on changed rows.

The goal is to update more quickly by just updating the changing content.
The update now focus on osm_id of changed rows, it use index. Add a where clause tags != update_tags(tags, geometry) to ensure only update when changed.

It requires one more trigger and a table to store changed osm_id.

The UPDATE is keep in a function to be reusable for initial setup and trigger update.

It is a based on the already merged https://github.com/openmaptiles/openmaptiles/pull/944

It is a separated PR as less obvious than previous. It replaces the reset of the `rank` field to NULL by missing value resulting of `LEFT JOIN`. It avoid triggering a new update on the table by reset the value then re-seting it to initial or new value.

It addresses #814.

Thanks @frodrigo

layers/water_name/update_marine_point.sql

@@ -1,42 +1,58 @@
 DROP TRIGGER IF EXISTS trigger_flag ON osm_marine_point;
+DROP TRIGGER IF EXISTS trigger_store ON osm_marine_point;
 DROP TRIGGER IF EXISTS trigger_refresh ON water_name_marine.updates;
 
-CREATE EXTENSION IF NOT EXISTS unaccent;
+CREATE SCHEMA IF NOT EXISTS water_name_marine;
 
-CREATE OR REPLACE FUNCTION update_osm_marine_point() RETURNS void AS
+CREATE TABLE IF NOT EXISTS water_name_marine.osm_ids
+(
+    osm_id bigint
+);
+
+CREATE OR REPLACE FUNCTION update_osm_marine_point(full_update boolean) RETURNS void AS
 $$
-BEGIN
-    -- etldoc: osm_marine_point              -> osm_marine_point
-    UPDATE osm_marine_point AS osm SET "rank" = NULL WHERE "rank" IS NOT NULL;
-
     -- etldoc: ne_10m_geography_marine_polys -> osm_marine_point
     -- etldoc: osm_marine_point              -> osm_marine_point
 
     WITH important_marine_point AS (
-        SELECT osm.geometry, osm.osm_id, osm.name, osm.name_en, ne.scalerank, osm.is_intermittent
-        FROM ne_10m_geography_marine_polys AS ne,
-             osm_marine_point AS osm
-        WHERE lower(trim(regexp_replace(ne.name, '\\s+', ' ', 'g'))) IN (lower(osm.name), lower(osm.tags->'name:en'), lower(osm.tags->'name:es'))
+        SELECT osm.osm_id, ne.scalerank
+        FROM osm_marine_point AS osm
+             LEFT JOIN ne_10m_geography_marine_polys AS ne ON
+              lower(trim(regexp_replace(ne.name, '\\s+', ' ', 'g'))) IN (lower(osm.name), lower(osm.tags->'name:en'), lower(osm.tags->'name:es'))
            OR substring(lower(trim(regexp_replace(ne.name, '\\s+', ' ', 'g'))) FROM 1 FOR length(lower(osm.name))) = lower(osm.name)
     )
     UPDATE osm_marine_point AS osm
     SET "rank" = scalerank
     FROM important_marine_point AS ne
-    WHERE osm.osm_id = ne.osm_id;
+    WHERE (full_update OR osm.osm_id IN (SELECT osm_id FROM water_name_marine.osm_ids))
+      AND osm.osm_id = ne.osm_id
+      AND "rank" IS DISTINCT FROM scalerank;
 
     UPDATE osm_marine_point
     SET tags = update_tags(tags, geometry)
-    WHERE COALESCE(tags->'name:latin', tags->'name:nonlatin', tags->'name_int') IS NULL;
+    WHERE (full_update OR osm_id IN (SELECT osm_id FROM water_name_marine.osm_ids))
+      AND COALESCE(tags->'name:latin', tags->'name:nonlatin', tags->'name_int') IS NULL
+      AND tags != update_tags(tags, geometry);
 
-END;
-$$ LANGUAGE plpgsql;
+$$ LANGUAGE SQL;
 
-SELECT update_osm_marine_point();
+SELECT update_osm_marine_point(true);
 
 CREATE INDEX IF NOT EXISTS osm_marine_point_rank_idx ON osm_marine_point ("rank");
 
 -- Handle updates
-CREATE SCHEMA IF NOT EXISTS water_name_marine;
+
+CREATE OR REPLACE FUNCTION water_name_marine.store() RETURNS trigger AS
+$$
+BEGIN
+    IF (tg_op = 'DELETE') THEN
+        INSERT INTO water_name_marine.osm_ids VALUES (OLD.osm_id);
+    ELSE
+        INSERT INTO water_name_marine.osm_ids VALUES (NEW.osm_id);
+    END IF;
+    RETURN NULL;
+END;
+$$ LANGUAGE plpgsql;
 
 CREATE TABLE IF NOT EXISTS water_name_marine.updates
 (
@@ -56,13 +72,21 @@ CREATE OR REPLACE FUNCTION water_name_marine.refresh() RETURNS trigger AS
 $$
 BEGIN
     RAISE LOG 'Refresh water_name_marine rank';
-    PERFORM update_osm_marine_point();
+    PERFORM update_osm_marine_point(false);
+    -- noinspection SqlWithoutWhere
+    DELETE FROM water_name_marine.osm_ids;
     -- noinspection SqlWithoutWhere
     DELETE FROM water_name_marine.updates;
     RETURN NULL;
 END;
 $$ LANGUAGE plpgsql;
 
+CREATE TRIGGER trigger_store
+    AFTER INSERT OR UPDATE OR DELETE
+    ON osm_marine_point
+    FOR EACH ROW
+EXECUTE PROCEDURE water_name_marine.store();
+
 CREATE TRIGGER trigger_flag
     AFTER INSERT OR UPDATE OR DELETE
     ON osm_marine_point