非super user管理会话

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在gp中取消或者中断某个用户的超长时间或者SQL存在问题的会话，如果无法拥有超级用户将无法执行该类操作。

首先我们创建两个用户t1、t2，并且使用t1登录到数据库。

[gpadmin@wx60 ~]$ psql gtlionspsql (8.2.15)Type "help" for help. gtlions=# select version();                                                                       version                                                                        ------------------------------------------------------------------------------------------------------------------------------------------------------ PostgreSQL 8.2.15 (Greenplum Database 4.2.7.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Feb 25 2014 18:05:04(1 row) gtlions=# \du                       List of roles Role name |            Attributes             | Member of -----------+-----------------------------------+----------- gpadmin   | Superuser, Create role, Create DB |  gtlions=# \dn       List of schemas        Name        |  Owner  --------------------+--------- gp_toolkit         | gpadmin information_schema | gpadmin pg_aoseg           | gpadmin pg_bitmapindex     | gpadmin pg_catalog         | gpadmin pg_toast           | gpadmin public             | gpadmin(7 rows) gtlions=# create user t1 ;NOTICE:  resource queue required -- using default resource queue "pg_default"CREATE ROLEgtlions=# create user t2;NOTICE:  resource queue required -- using default resource queue "pg_default"CREATE ROLEgtlions=# \c gtlions t1You are now connected to database "gtlions" as user "t1".

接下来我们使用用户t2登录到数据库，检查当前会话并尝试取消或者中断用户t1的会话。

[gpadmin@wx60 ~]$ psql -U t2 gtlionspsql (8.2.15)Type "help" for help. gtlions=> select * from pg_stat_activity ; datid | datname | procpid | sess_id | usesysid | usename |          current_query           | waiting |          query_start          |         backend_start         | client_addr | client_port | application_name |          xact_start           -------+---------+---------+---------+----------+---------+----------------------------------+---------+-------------------------------+-------------------------------+-------------+-------------+------------------+------------------------------- 16992 | gtlions |    3395 |      13 |    25881 | t2      | select * from pg_stat_activity ; | f       | 2014-10-11 09:25:56.197394+08 | 2014-10-11 09:25:43.293684+08 |             |          -1 | psql             | 2014-10-11 09:25:56.197394+08 16992 | gtlions |    3384 |      12 |    25880 | t1      | <insufficient privilege>         |         |                               |                               |             |             | psql             | (2 rows) gtlions=> select pg_cancel_backend(3384);ERROR:  must be superuser to signal other server processesgtlions=>

会发现非超级用户无法执行取消或者中断其他用户的会话操作。

解决办法是自定义一个函数，并授权给t2用户执行权限，这样就可以实现上述操作了。

create or replace function session_mgr(procpid integer, opertype character)returns booleanas$BODY$declareret boolean;beginif opertype = 'c' thenret := (select pg_catalog.pg_cancel_backend(procpid));elsif opertype = 'k' thenret := (select pg_catalog.pg_terminate_backend(procpid));end if;return ret;end;$BODY$  LANGUAGE plpgsql security definer;  gtlions=# grant execute on function session_mgr(integer, character) to t2;GRANTgtlions=# \c gtlions t1You are now connected to database "gtlions" as user "t1".gtlions=>

接着使用用户t2进行相关操作。

[gpadmin@wx60 ~]$ psql -U t2 gtlionspsql (8.2.15)Type "help" for help. gtlions=> select * from pg_stat_activity ; datid | datname | procpid | sess_id | usesysid | usename |          current_query           | waiting |          query_start          |         backend_start         | client_addr | client_port |      application_name      |          xact_start           -------+---------+---------+---------+----------+---------+----------------------------------+---------+-------------------------------+-------------------------------+-------------+-------------+----------------------------+------------------------------- 16992 | gtlions |    4034 |      19 |    25881 | t2      | select * from pg_stat_activity ; | f       | 2014-10-11 09:48:53.767859+08 | 2014-10-11 09:48:51.285594+08 |             |          -1 | psql                       | 2014-10-11 09:48:53.767859+08 16992 | gtlions |    3678 |      15 |       10 | gpadmin | <insufficient privilege>         |         |                               |                               |             |             | pgAdmin III - ?????????    |  16992 | gtlions |    3704 |      16 |       10 | gpadmin | <insufficient privilege>         |         |                               |                               |             |             | pgAdmin III - ???????????? |  16992 | gtlions |    4023 |      18 |    25880 | t1      | <insufficient privilege>         |         |                               |                               |             |             | psql                       | (4 rows)gtlions=> select session_mgr(4023,'c'); session_mgr ------------- t(1 row) gtlions=> select * from pg_stat_activity ; datid | datname | procpid | sess_id | usesysid | usename |          current_query           | waiting |          query_start          |         backend_start         | client_addr | client_port |      application_name      |          xact_start           -------+---------+---------+---------+----------+---------+----------------------------------+---------+-------------------------------+-------------------------------+-------------+-------------+----------------------------+------------------------------- 16992 | gtlions |    4034 |      19 |    25881 | t2      | select * from pg_stat_activity ; | f       | 2014-10-11 09:52:03.279186+08 | 2014-10-11 09:48:51.285594+08 |             |          -1 | psql                       | 2014-10-11 09:52:03.279186+08 16992 | gtlions |    4065 |      20 |       10 | gpadmin | <insufficient privilege>         |         |                               |                               |             |             | pgAdmin III - ???????????? |  16992 | gtlions |    3678 |      15 |       10 | gpadmin | <insufficient privilege>         |         |                               |                               |             |             | pgAdmin III - ?????????    |  16992 | gtlions |    3704 |      16 |       10 | gpadmin | <insufficient privilege>         |         |                               |                               |             |             | pgAdmin III - ???????????? |  16992 | gtlions |    4023 |      18 |    25880 | t1      | <insufficient privilege>         |         |                               |                               |             |             | psql                       | (5 rows) gtlions=> select session_mgr(4023,'k'); session_mgr ------------- t(1 row) gtlions=> select * from pg_stat_activity ; datid | datname | procpid | sess_id | usesysid | usename |          current_query           | waiting |          query_start          |         backend_start         | client_addr | client_port |      application_name      |          xact_start           -------+---------+---------+---------+----------+---------+----------------------------------+---------+-------------------------------+-------------------------------+-------------+-------------+----------------------------+------------------------------- 16992 | gtlions |    4034 |      19 |    25881 | t2      | select * from pg_stat_activity ; | f       | 2014-10-11 09:52:28.473137+08 | 2014-10-11 09:48:51.285594+08 |             |          -1 | psql                       | 2014-10-11 09:52:28.473137+08 16992 | gtlions |    4065 |      20 |       10 | gpadmin | <insufficient privilege>         |         |                               |                               |             |             | pgAdmin III - ???????????? |  16992 | gtlions |    3678 |      15 |       10 | gpadmin | <insufficient privilege>         |         |                               |                               |             |             | pgAdmin III - ?????????    |  16992 | gtlions |    3704 |      16 |       10 | gpadmin | <insufficient privilege>         |         |                               |                               |             |             | pgAdmin III - ???????????? |  16992 | gtlions |    4189 |      21 |    25880 | t1      | <insufficient privilege>         |         |                               |                               |             |             | psql                       | (5 rows) gtlions=>

最后检查下t1当前进程。

gtlions=> select version();FATAL:  terminating connection due to administrator commandserver closed the connection unexpectedly        This probably means the server terminated abnormally        before or while processing the request.The connection to the server was lost. Attempting reset: Succeeded.

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