SELECT l.database AS db_oid, 
             d.datname,
            l.relation, 
           n.nspname,
           c.relname,
           a.pid,
           a.usename,
           l.locktype,
           l. mode, 
           l. granted,
           l.tuple 
  FROM pg_locks l
  JOIN pg_class c ON (c.oid = l.relation)
  JOIN pg_namespace n ON (n.oid = c.relnamespace)
  JOIN pg_database d    ON (d.oid = l.database)
  JOIN pg_stat_activity a ON (a.pid = l.pid) 
ORDER BY database,
         relation, 
         pid;