Session IDs Growing Very Large Randomly

We have a table and logging mechan开发者_如何学JAVAism that logs customers that log in with a Session ID. However, one thing we notice is that sometimes the Session ID information tends to grow quite large growing beyond a 255 character ID. How can we stop it from doing this?

This page seems to discuss the subject http://forums.asp.net/p/1264093/2370866.aspx

It seems you need to make your own session manager