Thanks for pointing out triggers!

So, ...a journal. (I hoped for a solution without it.) Actually, in one implementation, it's what I already use. Seems to be the easier method of computing things like a per-user "activity log".

My challenge with such a journal so far has been: what's the best (actually working/usable) way to interlock eav-table and journal-table? (Suggestions welcome) As one usually has to track who did what, which attributes (attr id) are involved, what was attr name (in case attr name is user changeable), what was value, what are the new values. So rollbacks actually work. But I'm babbling... Probably that's why, apart from perfomance, many people hate EAV: for versioning, the traditional design offers the fuzzy feeling of having a rigid backlog of old version snapshots, ready to be unearthed at any time, diff'ed against any version... The table model is tempting. But then, there's the natural goodness of freely attributing stuff... I guess that's the ongoing struggle of NoSQL or things like BigTable where you can tweak and extend the column schema to the max. Arg! After babbling, now I'm even going into musing... anyway.

Thank you, Corion!