I need to calculate the peak number of users we have on our web application on a given day.
i can calculate the total number of users on a given day no problem with a MySQL DISTINCT clause, but not sure how to work out peak concurrent users for a given day.
There is a session log which is updated as users login and logout of the system (with an auto logoff).
*note all sessions are automatically terminated at 10pm for overnight processing so no sessions run from one day to the next.
The key fields in the MySQL session log table are.
sessionId - unsigned int - auto increment
userId - unsigned int
loginTime - timestamp
logoutTime - timestamp