motorway_links.sql

SELECT 
    w1.id AS link_id
  FROM ways w1
    JOIN nodes n ON (w1.nodes[1] = n.id)
    JOIN (
      SELECT wn.node_id, wn.way_id, tags, nodes FROM way_nodes wn JOIN ways w ON (wn.way_id = w.id) 
        WHERE w.tags @> hstore('highway','motorway')
      ) AS wn1 ON (wn1.node_id = n.id)
    LEFT JOIN (
      SELECT wn.node_id, wn.way_id, tags, nodes FROM way_nodes wn JOIN ways w ON (wn.way_id = w.id) 
        WHERE w.tags @> hstore('highway','motorway')
      ) AS wn2 ON (wn2.node_id = n.id AND wn2.way_id != wn1.way_id)
    LEFT JOIN (
      SELECT wn.node_id, wn.way_id, tags, nodes FROM way_nodes wn JOIN ways w ON (wn.way_id = w.id) 
        WHERE w.tags @> hstore('highway','motorway')
      ) AS wn3 ON (wn3.node_id = n.id AND wn3.way_id != wn1.way_id AND wn3.way_id != wn2.way_id)    
  WHERE w1.tags @> hstore('highway','motorway_link')
    AND n.tags ? 'exit_to'
    AND w1.linestring && ST_MakeEnvelope(-125, 40, 50, -120, 4326)
    AND (
      (wn2.node_id IS NULL AND NOT (n.id = wn2.nodes[1] OR n.id = wn2.nodes[array_upper(wn2.nodes,1)]))
      OR (
        wn2.node_id IS NOT NULL AND wn3.node_id IS NULL 
        AND (n.id = wn2.nodes[1] OR n.id = wn2.nodes[array_upper(wn2.nodes,1)])
        AND (n.id = wn3.nodes[1] OR n.id = wn3.nodes[array_upper(wn3.nodes,1)])
      )
    );