postgres show blocked and blocking queries

SELECT
  COALESCE(blockingl.relation::regclass::text,blockingl.locktype) as locked_item,
  blockeda.procpid AS blocked_pid,
  blockeda.current_query as blocked_query,
  blockedl.mode as blocked_mode,
  blockinga.procpid AS blocking_pid,
  blockinga.current_query as blocking_query,
  blockingl.mode as blocking_mode
FROM pg_catalog.pg_locks blockedl
JOIN pg_stat_activity blockeda ON blockedl.pid = blockeda.procpid
JOIN pg_catalog.pg_locks blockingl ON (
  ( blockingl.transactionid=blockedl.transactionid
    OR
    (blockingl.relation=blockedl.relation AND blockingl.locktype=blockedl.locktype)
  )
  AND blockedl.pid != blockingl.pid
)
JOIN pg_stat_activity blockinga ON blockingl.pid = blockinga.procpid
WHERE NOT blockedl.granted;