非super user管理会话

傷城~ 2022-03-30 11:26 260阅读 0赞

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。假设无法拥有超级用户将无法运行该类操作。  
  
首先我们创建两个用户t1、t2，而且使用t1登录到数据库。

[gpadmin@wx60 ~]$ psql gtlions
    psql (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 ROLE
    gtlions=# create user t2;
    NOTICE:  resource queue required -- using default resource queue "pg_default"
    CREATE ROLE
    gtlions=# \c gtlions t1
    You 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。

会发现非超级用户无法运行取消或者中断其它用户的会话操作。  
  
解决的方法是自己定义一个函数，并授权给t2用户运行权限。这样就能够实现上述操作了。

create or replace function session_mgr(procpid integer, opertype character)
    	returns boolean
    	as
    $BODY$
    declare
    	ret boolean;
    begin
    	if opertype = 'c' then
    		ret := (select pg_catalog.pg_cancel_backend(procpid));
    	elsif opertype = 'k' then
    		ret := (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;
    GRANT
    gtlions=# \c gtlions t1
    You are now connected to database "gtlions" as user "t1".
    gtlions=>

接着使用用户t2进行相关操作。

??? | 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 command
    server 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.

\-EOF-