PHP forums - how to cope with unread discussions / topics / posts

Question

I know this question has been asked here a couple of times, but none of the answers had pleased me. This is because almost all of them involve a huge read / write process re

Answer 1

Almost any forum I know of will use some sort of reference timestamp to determine whether or not a thread/message should be regarded as "unread" or not. This timestamp usually is the date/time of the last action you performed on your previous visit to the forum.

So you keep ie. a previous_last_action & last_action timestamp in your user table, last_action is updated on every user action, the previous_last_action column is set once to last_action when logging in (or upon creation of a new session - if you have "remember me" functionality). To determine if a thread/message is unread you would compare that thread/message creation (or update) timestamp with the value in previous_last_action for the user currently logged in.