pg listen/notify part

pg/send_block_changes.sql

@@ -0,0 +1,23 @@
+BEGIN;
+
+  CREATE OR REPLACE FUNCTION send_block_changes()
+  RETURNS TRIGGER AS
+$$
+BEGIN
+  PERFORM pg_notify('blockchanges',
+    json_build_object(
+      'X', NEW.posx,
+      'Z', NEW.posz
+    )::text
+  );
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER blocks_changed
+  AFTER INSERT OR UPDATE
+  ON blocks
+  FOR EACH ROW
+  EXECUTE PROCEDURE send_block_changes();
+
+END;