我只是尝试在我的数据库中的一个表中添加一列，但这是永远的。
alter table xxx add column frame_weight float;
select * from pg_locks ;
locktype | database | relation | page | tuple | virtualxid | transactionid | classid | objid | objsubid | virtualtransaction | pid | mode | granted | fastpath
-----------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+-------+-----------------+---------+----------
relation | 16387 | 60737 | | | | | | | | 3/136193 | 17977 | AccessShareLock | t | t
relation | 16387 | 60748 | | | | | | | | 3/136193 | 17977 | AccessShareLock | t | t
relation | 16387 | 60781 | | | | | | | | 3/136193 | 17977 | AccessShareLock | t | t
relation | 16387 | 60733 | | | | | | | | 3/136193 | 17977 | AccessShareLock | t | t
relation | 16387 | 60774 | | | | | | | | 3/136193 | 17977 | AccessShareLock | t | t
virtualxid | | | | | 3/136193 | | | | | 3/136193 | 17977 | ExclusiveLock | t | t
relation | 16387 | 11069 | | | | | | | | 2/4820 | 20752 | AccessShareLock | t | t
virtualxid | | | | | 2/4820 | | | | | 2/4820 | 20752 | ExclusiveLock | t | t
relation | 16387 | 60741 | | | | | | | | 3/136193 | 17977 | AccessShareLock | t | f
select * from pg_stat_activity where pid = 17977;
datid | datname | pid | usesysid | usename | application_name | client_addr | client_hostname | client_port | backend_start | xact_start | query_start | state_change | waiting | state | query
-------+---------+-------+----------+---------+------------------+-------------+-----------------+-------------+-------------------------------+-------------------------------+-------------------------------+-------------------------------+---------+--------+--------
16387 | xx | 17977 | 16385 | xx | | 127.0.0.1 | | 50626 | 2018-05-10 20:13:06.001069-04 | 2018-05-10 20:13:06.251093-04 | 2018-05-10 20:13:06.251369-04 | 2018-05-10 20:13:06.251372-04 | f | active | SELECT
select pg_cancel_backend (17977);
pg_cancel_backend
-------------------
t
(1 row)
然后我给出了终止命令 -
select pg_terminate_backend (17977);
pg_terminate_backend
----------------------
t
(1 row)
尝试完所有后，alter命令仍然需要很长时间。有人可以建议可能出错的地方吗？
如果您不喜欢这个问题，请不要贬低。只需告诉我，我将删除它。我是一个绝对的初学者，在这个社区的贡献或学习方面，我非常伤心。谢谢！
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