check the root blocker and kill it

Today On OTN this question has been asked how to check the root killer and kill it, While searching and browsing i found nice article i would love to share written by Moid I would thank him for his sharing and amazing topics

Step #1 : 
Create a view called root_blocker, and Grant read only permission to  public

Create or replace view root_blocker
as
    (select
       to_char(a.logon_time, ‘MM/DD/YY HH:MI:SS’) as Logon_Time,
       a.inst_id,
       b.username||’@’||a.machine as blocker,
       a.sql_id,
       c.sql_text,
       ‘(‘||a.sid||’,’||a.serial#||’)’ as root_blockers_sid_n_serial#,
       ‘ALTER SYSTEM KILL SESSION ”’|||a.sid||’,’||a.serial#||”’ IMMEDIATE;’ as “10g Command to kill session”,
       ‘ALTER SYSTEM KILL SESSION ”’||a.sid||’,’||a.serial#||’@’||a.inst_id||”’ IMMEDIATE;’ as “11g Command to kill session”
    from
       gv$session a,
       dba_users b,
       gv$sqltext c
    where
       b.username=a.username
       and a.sql_id=c.sql_id
       and logon_time=(select
                       max(logon_time)
                   from
                       V$session
                   where blocking_session_status=’VALID’)
    );

 Step #2:
Now, using the help of plan_table, let’s display the values vertically so that it is easier for us to read the output.

set linesize 300
SET SERVEROUTPUT ON FORMAT WRAPPED
exec print_table( ‘select * from sys.root_blocker’ );

SQL> exec print_table(‘select * from sys.root_blocker’);
LOGON_TIME                    : 09/25/10 01:17:37
INST_ID                       : 1
USERNAME                      : SCOTT
SQL_ID                        : 4t5dk4yfn6gx8
SQL_TEXT                      :  update t11 set sal=2001 where empno=7521
ROOT_BLOCKERS_SID_N_SERIAL#   : (73,22025)

 and you could kill it like the below screen shot :

Step #3:
To check the complete list of locked_session/blockers, use the following query.

select
    to_char(a.logon_time, ‘MM/DD/YY HH:MI:SS’) as Logon_Time,
    a.inst_id,
    b.username||’@’||a.machine as blocker,
    a.sql_id,
    c.sql_text,
    ‘(‘||a.sid||’,’||a.serial#||’)’ as root_blockers_sid_n_serial#,
    ‘ALTER SYSTEM KILL SESSION ‘||a.sid||’,’||a.serial#||”’ IMMEDIATE;’ as “10g Command to kill session”,
    ‘ALTER SYSTEM KILL SESSION ”’||a.sid||’,’||a.serial#||’@’||a.inst_id||”’ IMMEDIATE;’ as “11g Command to kill session”
from
    gv$session a,
    dba_users b,
    gv$sqltext c
where
    b.username=a.username
    and a.sql_id=c.sql_id
    and a.blocking_session_status=’VALID’

order by logon_time desc;

Original Post Here

Thank you