[eluser]jedd[/eluser]
[quote author="andrewtheandroid" date="1257469573"]
Lets say we are only really interested in the last (say 30) topics.
[/quote]
As soon as you set arbitrary limits for things like this, you strike a whole raft of new problems I think.
I'm not sure from your code sample and subsequent explanation was an adjustment of my idea, or an extrapolation of your original .. but apart from the problems with arbitrary figures (which you hint at yourself) there's the fact that time fields are more complex than integers, especially when you bring in timezones (of course, you tend to keep all database dates and times as local, but still ...).
In any case, I can't see any advantage to tracking via time rather than message number.
What I decided in the end was pretty much what I described in that thread. And you're right - it's much easier if you sort out the design up front - I started a few different approaches in code before I just put it off and let the back bit of my brain dwell on it for a while. There's probably a few things that will be hard for me to implement later, but I think I got most of the interesting functionality sorted (or at least sortable).
