Session with URL Var or DB which is better

Timelimit control

[HeadBut]

Which is most popular/convenient/safest for timelimit control, a URL timestamp or a table with last visit timestamp. I'm thinking to use the database solution to give me the option of users online reporting? Is the database solution too slow is it safest?

thanks

[ergophobe]

Database solution shouldn't be slow.

The problem with the URL solution, is it's going to mess up any bookmarks or, worse, if someone sends the URL to a friend who visits within the time allotment, they'll be right in on the same session unless you're checking IPs or something.

[HeadBut]

So, at least for URL's the time stamp should be verified after the session is verified and should still deliver the user to the correct page after they sign-in. This could get complicated. Would need a way to save the URL in a session var and then re-parse it and figure out the original desired location.
This may be a reason to stick with a database solution.