WITH zona04 AS (
  SELECT tags, geom
  FROM postpass_polygon
  WHERE
  (
    -- Bounding box: City of Livorno.
    ST_intersects(geom, ST_MakeEnvelope(9.888339, 43.419635, 10.419938, 43.595488, 4326))
    -- Type of entries: Administrative subdivisions.
    AND tags->>'admin_level'='10'
    -- Entity: Consiglio di Zona 4 (https://www.wikidata.org/wiki/Q138390876).
    AND tags->>'wikidata'='Q138390876'
  )
)
SELECT p.tags, p.geom
FROM postpass_pointlinepolygon p, zona04
WHERE
(
  -- Bounding box: zona04 boundaries.
  ST_Intersects(zona04.geom, p.geom)
  -- Type of entries: Bicycle parkings.
  AND p.tags->>'amenity'='bicycle_parking'
)