Is sessions stored somewhere? - oracle

Question

The V$SESSION view contains the list of users currently logged in, but are they stored somewhere in a log table or something?
I need to get a list of yesterday users that where logged in with pl/sql (for instance)

Answer 1

By default Oracle doesn't store such information. You have a couple of options:
Enable auditing of system events (longon\logoff in this case).
Write system event(after longon, before logoff) trigger to gather that information.
Here are examples:
SQL> show parameter audit_trail
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
audit_trail string DB, EXTENDED
SQL> select sessionid
2 , userid
3 , decode(action#, 100, 'logon', 101, 'logoff')
4 from sys.aud$
5 where action# in (100, 101);
no rows selected
SQL> audit connect;
Audit succeeded.
SQL> conn hr/hr
Connected.
SQL> select sessionid
2 , userid
3 , decode(action#, 100, 'logon', 101, 'logoff')
4 from sys.aud$
5 where action# in (100, 101);
SESSIONID USERID DECODE
---------- ------------------------------ ------
1000712 HR logon
SQL> conn hr/hr
Connected.
SQL> select sessionid
2 , userid
3 , decode(action#, 100, 'logon', 101, 'logoff')
4 from sys.aud$
5 where action# in (100, 101);
SESSIONID USERID DECODE
---------- ------------------------------ ------
1000712 HR logon
1000712 HR logoff
1000713 HR logon
And example with triggers:
SQL> create table Logon_history(
2 sessionid number,
3 userid varchar2(31),
4 logon_date timestamp,
5 logoff_date timestamp
6 )
7 ;
Table created
SQL> create or replace trigger TR_LOGON_STAT after logon
2 on database
3 begin
4 insert into Logon_history(Sessionid, Userid, Logon_Date, Logoff_Date)
5 values(sys_context('userenv', 'sessionid'), user, systimestamp, null);
6 end;
7 /
Trigger created
SQL> create or replace trigger TR_LOGOFF_STAT before logoff
2 on database
3 begin
4 insert into Logon_history(Sessionid, Userid, Logon_Date, Logoff_Date)
5 values(sys_context('userenv', 'sessionid'), user, null,systimestamp);
6 end;
7 /
Trigger created
SQL> select sessionid
2 , userid
3 , logon_date
4 , logoff_date
5 from Logon_history
6 ;
no rows selected
SQL> conn hr/hr
Connected.
SQL> select sessionid
2 , userid
3 , logon_date
4 , logoff_date
5 from Logon_history
6 ;
Sessionid Userid Logon_Date Logoff_Date
--------------------------------------------------------------------------------
2490674 HR 01-NOV-12 11.46.23.421000 PM
2490672 HR 01-NOV-12 11.46.23.343000 PM