如何查看PostgreSQL正在执行的SQL

SELECT       procpid,       start,       now() - start AS lap,       current_query   FROM       (SELECT           backendid,           pg_stat_get_backend_pid(S.backendid) AS procpid,           pg_stat_get_backend_activity_start(S.backendid) AS start,          pg_stat_get_backend_activity(S.backendid) AS current_query       FROM           (SELECT pg_stat_get_backend_idset() AS backendid) AS S       ) AS S   WHERE      current_query <> '<IDLE>'   ORDER BY      lap DESC;