我正在尝试获取阻止和阻止用户的用户名,但我得到一个空数组。
这就是我尝试过的:
select pid,
usename,
pg_blocking_pids(pid) as blocked_by, (select usename from
pg_stat_activity where pid=ANY(pg_blocking_pids(pid)))
from pg_stat_activity
where cardinality(pg_blocking_pids(pid)) > 0;
嵌套的select返回[null]。
这就是如果我查询选择手动插入像这样的pid值
select usename from pg_stat_activity where pid=ANY(pg_blocking_pids(14648));
我得到了我正在寻找的价值。
我认为你需要一个相关条款:
select sa.pid, sa.usename,
pg_blocking_pids(sa.pid) as blocked_by,
(select sa2.usename
from pg_stat_activity sa2
where sa2.pid = ANY(pg_blocking_pids(sa.pid)))
from pg_stat_activity sa
where cardinality(pg_blocking_pids(sa.pid)) > 0;
如果您收到错误声明子查询返回多行,您将知道这是有效的。在这种情况下,将array_agg()
添加到子查询中。