text: set client_min_messages to ERROR;
  
  \i load_topology.sql
  
  SELECT 'R'||edge_id, (topology.GetRingEdges('city_data', edge_id)).* 
  	FROM city_data.edge;
  
  SELECT 'R-'||edge_id, (topology.GetRingEdges('city_data', -edge_id)).* 
  	FROM city_data.edge;
  
  SELECT topology.DropTopology('city_data');
  