How long?

I have observed that there are many user sessions which are inactive .The logon time shows that they have been connected for a few days now. How can I find out for how long the session has been inactive?

And also what is the difference between the status values of V$SESSION - Inactive and Snipe.

The time session has been idle can be determined from V$SESSION.LAST_CALL_ET. It shows the time (in seconds) since the session has isued its last call to the database.

Thanks.

When I saw the above columns data, it shows that the background processes never accessed the database from the startup.

????

Well, it is obvious that Oracle does not record background process's actions in this column. And why should it? It would be pure useless overhead. I belive recording of last calls of "normal" sessions in V$SESSION.LAST_CALL_ET was implemented primarily to support limiting session's idle times in profiles. And since background processes do not belong to any profile there is no need to record the time of their last calls.