SESSION:Find current active users in my app???

[eluser]mindprojects[/eluser]
[quote author="BrianDHall" date="1255387897"]Setup your CI sessions to use a database, then be sure to record the important info in Session variables.

Then you should be able to test out some logins and such to populate your session info, and then look through the ci sessions table in your database to get an idea how you can do it.

Once you do that it should be pretty straightforward.[/quote]

1)Setup your CI sessions to use a database
Done

2)to record the important info in Session variables
Now i can getession_id,ip_address,last_activity,user_agent

3)Then you should be able to test out some logins:
The problem is that the SESSION ID is regenerated every x seconds,isn't it?
So,what do you mean? Should I hack the session library and create a session field where to update(for every session refresh) the user_id of the user logged in?
Second point how can i get the live sessions?Getting the last activity record ,less the refresh time?
I mean:

SELECT *,user_id,last_activity as last FROM ci_sessions WHERE last <= (SELECT last_activity from ci_sessions WHERE last_activity >= (NOW() - expiration_time) ORDER BY last_activity ASC LIMIT 0,1)

Could it be the right way?
Thanks