若需要终止特定的SQL或会话来恢复系统状态,先通过pg_stat_activity系统视图查询当前的查询:

select current_query,procpid from pg_stat_activity ;

                    current_query                    | procpid
-----------------------------------------------------+---------
 select current_query,procpid from pg_stat_activity; |   32584
 SELECT xxx                                          |   32238
说明 current_query为当前正在进行的查询, procpid为后台进程的PID。

终止非当前连接的SELECT:

SELECT pg_cancel_backend(pg_stat_activity.procpid)
FROM pg_stat_activity
WHERE procpid <> pg_backend_pid() and current_query like 'SELECT%';--注意SELECT的大小写

 pg_cancel_backend
-------------------
 t
(1 rows)

SELECT pg_terminate_backend(pg_stat_activity.procpid)
FROM pg_stat_activity
WHERE procpid <> pg_backend_pid() and current_query like 'SELECT%'; --注意SELECT的大小写

 pg_terminate_backend
-------------------
 t
(1 rows)
说明 cancelterminate仅适用于当前用户的查询或权限小于等于当前用户的查询。若提示 "ERROR: must be superuser or rds_superuser to signal other server processes",则说明后台有其他用户的连接,但不影响 cancelterminate的执行。