Edit
I tried limiting by using st_buffer and st_dwithin, but neither of them works, something like:
SELECT *
FROM pgr_dijkstra('
SELECT osm_id as id, osm_source_id as source, osm_target_id as target,length as cost FROM pl_2po_4pgr
WHERE geom && st_buffer(st_makeline(
st_setsrid(st_makepoint(-122.39212 46.95), 4326),
st_setsrid(st_makepoint(-122.360618 47.186731), 4326)
), 100
)',
110491754, 110490812, false
);
SELECT *
FROM pgr_dijkstra('
SELECT osm_id as id, osm_source_id as source, osm_target_id as target,length as cost FROM pl_2po_4pgr
WHERE st_dwithin(geom,
st_setsrid(st_makepoint(-122.39212 46.95), 4326)
), 1000
)',
110491754, 110490812, false
);