Kaijiang Chen <chenkaijiang@gmail.com> writes: > I'm using postgres 9.4.17 on centos 7. > I check the running queries with the following 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;
Don't know where you got this query from, but it's wrong for any PG version more recent than (I think) 9.1. We don't use "<IDLE>" as an indicator of idle sessions anymore; rather, those can be identified by having state = 'idle'. What's in the query column for such a session is its last query.
> Then, I found a SQL that has run for some days (and still running): > procpid | 32638 > start | 2019-11-25 16:29:29.529318+08 > lap | 21 days 18:24:54.707369 > current_query | DEALLOCATE pdo_stmt_00000388
It's not running. That was the last query it ran, back in November :-( You could zap the session with pg_terminate_backend(), but pg_cancel_backend() is not going to have any effect because there's no active query.
