Killing Oracle sessions

See here for recent notes on alter system kill session.

Methods of Murder by Mike Ault

Other than the aforementioned abort option for the SHUTDOWN command, which after all is rather rude, what are the methods of killing these recalcitrant sessions? Essentially, you can issue an ALTER SYSTEM KILL SESSION or you can issue a manual process kill command such as the UNIX: kill -9 pid from the operating system side. You should do one or the other of these types of kill operations, but not both. If you kill both the Oracle process and the operating system process, it can result in database hang situations, which will force you to perform a shutdown abort. 

Killing from the Oracle Side

The DBA can either issue a series of ALTER SYSTEM commands manually or develop a dynamic SQL script to perform the operation. Source 2.3 shows a PL/SQL procedure to perform a kill of a process using the dynamic SQL package of procedures: DBMS_SQL. In Oracle8i, a new option is available for the ALTER SYSTEM that allows disconnection of the user process after a transaction completes. The commented-out section in Source 2.3 shows this alternative to a straight kill.      

Using the procedure from Source 2.3 the DBA can then create a quick SQL procedure to remove the nonrequired Oracle sessions from the Oracle side. An example of this procedure is shown in Source 2.4. An example of the output from ora_kill.sql (kill_all.sql) is shown in Listing 2.4.

See Code Depot

Important Oracle 11g changes to alter session kill session

Oracle author Mladen Gogala notes that an @ sign is now required to kill a session when using the inst_id column:

SQL> select inst_id,sid,serial# from gv$session where username='SCOTT';

   INST_ID        SID    SERIAL#
---------- ---------- ----------
         1        130        620

SQL>  alter system kill session '130,620,1';
 alter system kill session '130,620,1'
*
ERROR at line 1:
ORA-00026: missing or invalid session ID

Now, it works:

SQL>  alter system kill session '130,620,@1';

System altered.

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