What Happens to the Current Transaction If the Session Is Killed? - Oracle DBA FAQ - Understanding SQL Transaction Management

If a session is killed by the DBA, the current transaction in that session will be rolled back and ended. All the database changes made in the current transaction will be removed. This is called an implicit rollback when session is killed. The following tutorial exercise shows you that the DBA KILL SESSION command forces the current transaction to be rolled back with all the changes uncommitted.

SQL> connect HR/fyicenter

SQL> SELECT * FROM fyi_links;
     ID URL              NOTES          COUNTS CREATED
------- ---------------- ---------- ---------- ---------
    101 FYICENTER.COM                          07-MAY-06
    110 CENTERFYI.COM                          07-MAY-06
    112 oracle.com                             07-MAY-06
    113 sql.com                                07-MAY-06

SQL> DELETE FROM fyi_links where id = 112;
1 row deleted.

SQL> DELETE FROM fyi_links where id = 113;
1 row deleted.

SQL> SELECT * FROM fyi_links;
     ID URL              NOTES          COUNTS CREATED
------- ---------------- ---------- ---------- ---------
    101 FYICENTER.COM                          07-MAY-06
    110 CENTERFYI.COM                          07-MAY-06

Keep the "HR" SQL*Plus window as is, and open another window to run another instance of SQL*Plus.

>cd (OracleXE home directory)
>.\bin\sqlplus /nolog

SQL> connect SYSTEM/password
Connected.

SQL> SELECT sid, serial#, username, status, type
  2  FROM V$SESSION WHERE username = 'HR';
       SID    SERIAL# USERNAME           STATUS   TYPE
---------- ---------- ------------------ -------- -----
        39        141 HR                 INACTIVE USER

SQL> ALTER SYSTEM KILL SESSION '39,141';
System altered.

Go back to the "HR" SQL*Plus window.

SQL> SELECT * FROM fyi_links;
ORA-00028: your session has been killed

SQL> connect HR/fyicenter

SQL> SELECT * FROM fyi_links;
     ID URL              NOTES          COUNTS CREATED
------- ---------------- ---------- ---------- ---------
    101 FYICENTER.COM                          07-MAY-06
    110 CENTERFYI.COM                          07-MAY-06
    112 oracle.com                             07-MAY-06
    113 sql.com                                07-MAY-06

As you can see, two records were rolled back as the session got killed by another session.