Terminating Sessions On a Specific Cluster Instance
You can use the ALTER SYSTEM KILL SESSION statement to terminate a session on a specific instance. When a session is terminated, any active transactions of the session are rolled back, and resources held by the session (such as locks and memory areas) are immediately released and available to other sessions.
Using this statement enables you to maintain strict application service-level agreements in Oracle RAC environments. Often, the goal of a service-level agreement is to execute a transaction in a specified time limit. In an Oracle RAC environment, this may require terminating a transaction on an instance and retrying the transaction on another instance within a specified time frame.
To terminate sessions, follow these steps:
-
Query the value of the
INST_IDcolumn in theGV$SESSIONdynamic performance view to identify which session to terminate -
Run the
ALTER SYSTEM KILL SESSIONand specify the session index number (SID) and serial number of a session that you identified with theGV$SESSIONdynamic performance view.KILL SESSION 'integer1, integer2[, @integer3]'
-
For
integer1, specify the value of the SID column. -
For
integer2, specify the value of the SERIAL# column. -
For the optional
integer3, specify the ID of the instance where the session to be killed exists. You can find the instance ID by querying theGV$tables.
To use this statement, your instance must have the database open, and your session and the session to be terminated must be on the same instance unless you specify
integer3. -
If the session is performing some activity that must be completed, such as waiting for a reply from a remote database or rolling back a transaction, then Oracle Database waits for this activity to complete, marks the session as terminated, and then returns control to you. If the waiting lasts a minute, then Oracle Database marks the session to be terminated and returns control to you with a message that the session is marked to be terminated. The PMON background process then marks the session as terminated when the activity is complete.
The following examples provide a three scenarios in which a user identifies and terminates a specific session.
In this example, assume that the executing session is SYSDBA on the instance INST_ID=1. The SYSDBA first queries the GV$SESSION view for theSCOTT user's session to identify the session to terminate, and then runs the ALTER SYSTEM KILL SESSION statement to terminate the session on the instance INST_ID=2. The ORA-00031 message is returned because some activity must be completed before the session can be terminated.
SQL> SELECT SID, SERIAL#, INST_ID FROM GV$SESSION WHERE USERNAME='SCOTT';
SID SERIAL# INST_ID
---------- ---------- ----------
80 4 2
SQL> ALTER SYSTEM KILL SESSION '80, 4, @2';
alter system kill session '80, 4, @2'
*
ERROR at line 1:
ORA-00031: session marked for kill
SQL>
In this example, assume that the executing session is SYSDBA on the instance INST_ID=1. The session on instance INST_ID=2 is terminated immediately when Oracle Database executes the statement within 60 seconds.
SQL> SELECT SID, SERIAL#, INST_ID FROM GV$SESSION WHERE USERNAME='SCOTT';
SID SERIAL# INST_ID
---------- ---------- ----------
80 6 2
SQL> ALTER SYSTEM KILL SESSION '80, 6, @2';
System altered.
SQL>
The following example include the optional IMMEDIATE clause to immediately terminate the session without waiting for outstanding activity to complete.
SQL> SELECT SID, SERIAL#, INST_ID FROM GV$SESSION WHERE USERNAME='SCOTT';
SID SERIAL# INST_ID
---------- ---------- ----------
80 8 2
SQL> ALTER SYSTEM KILL SESSION '80, 8, @2' IMMEDIATE;
System altered.
SQL>
See Also:
Oracle Database Administrator's Guide for more information about terminating sessions