diff --git a/layers/park/update_park_polygon.sql b/layers/park/update_park_polygon.sql
index 69492692..3e9a2425 100644
--- a/layers/park/update_park_polygon.sql
+++ b/layers/park/update_park_polygon.sql
@@ -46,6 +46,8 @@ DROP TRIGGER IF EXISTS update_row ON osm_park_polygon_gen_z7;
 DROP TRIGGER IF EXISTS update_row ON osm_park_polygon_gen_z6;
 DROP TRIGGER IF EXISTS update_row ON osm_park_polygon_gen_z5;
 DROP TRIGGER IF EXISTS update_row ON osm_park_polygon_gen_z4;
+DROP TRIGGER IF EXISTS tigger_flag ON osm_park_polygon;
+DROP TRIGGER IF EXISTS tigger_refresh ON park_polygon.updates;
 
 -- etldoc:  osm_park_polygon ->  osm_park_polygon
 -- etldoc:  osm_park_polygon_gen_z13 ->  osm_park_polygon_gen_z13
@@ -119,6 +121,42 @@ CREATE INDEX IF NOT EXISTS osm_park_polygon_gen_z5_point_geom_idx ON osm_park_po
 CREATE INDEX IF NOT EXISTS osm_park_polygon_gen_z4_polygon_geom_idx ON osm_park_polygon_gen_z4 USING gist (geometry);
 CREATE INDEX IF NOT EXISTS osm_park_polygon_dissolve_z4_polygon_geom_idx ON osm_park_polygon_dissolve_z4 USING gist (geometry);
 
+CREATE SCHEMA IF NOT EXISTS park_polygon;
+
+CREATE TABLE IF NOT EXISTS park_polygon.updates
+(
+    id serial PRIMARY KEY,
+    t  text,
+    UNIQUE (t)
+);
+
+CREATE OR REPLACE FUNCTION park_polygon.flag() RETURNS trigger AS
+$$
+BEGIN
+    INSERT INTO park_polygon.updates(t) VALUES ('y') ON CONFLICT(t) DO NOTHING;
+    RETURN NULL;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION park_polygon.refresh() RETURNS trigger AS
+$$
+DECLARE
+    t TIMESTAMP WITH TIME ZONE := clock_timestamp();
+BEGIN
+    RAISE LOG 'Refresh park_polygon';
+
+    -- Analyze tracking and source tables before performing update
+    ANALYZE osm_park_polygon_gen_z4;
+    REFRESH MATERIALIZED VIEW osm_park_polygon_dissolve_z4;
+
+    -- noinspection SqlWithoutWhere
+    DELETE FROM park_polygon.updates;
+
+    RAISE LOG 'Refresh park_polygon done in %', age(clock_timestamp(), t);
+    RETURN NULL;
+END;
+$$ LANGUAGE plpgsql;
+
 CREATE OR REPLACE FUNCTION update_osm_park_polygon_row()
     RETURNS trigger
 AS
@@ -206,3 +244,15 @@ CREATE TRIGGER update_row
     FOR EACH ROW
 EXECUTE PROCEDURE update_osm_park_dissolved_polygon_row();
 
+CREATE TRIGGER trigger_flag
+    AFTER INSERT OR UPDATE OR DELETE
+    ON osm_park_polygon_gen_z4
+    FOR EACH STATEMENT
+EXECUTE PROCEDURE park_polygon.flag();
+
+CREATE CONSTRAINT TRIGGER trigger_refresh
+    AFTER INSERT
+    ON park_polygon.updates
+    INITIALLY DEFERRED
+    FOR EACH ROW
+EXECUTE PROCEDURE park_polygon.refresh();