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Back from some holiday, I was thinking about how to (automatically) manage user-generated content. On a website where users can add and change data, how does one make sure that it is entered correctly and that it will not be vandalized afterwards? Maybe I am paranoid, but I think if there is a possibility to ruin something online, it will be ruined.

Let us take a website where users can add events and their details as an example. What if an event is fake? Also, what about duplicates (different names for the same actual event)? Last.fm takes an interesting approach letting users vote for the right names of the artists. After some number and/or percent of positive votes, it would be possible to assume that event details are correct and lock it to prevent further editing.

But what if the event details actually need to be changed? Should only the creator be allowed to make changes, or everybody? In that case, how to make sure that a description carefully crafted by several users will not be wiped out by somebody? As far as I can see, it needs at least some version tracking to be able to roll back to the right version, as in Last.fm's description wiki and Wikipedia. But the implementation on a relational database does not seem trivial for me. Can anyone provide an example? I think it would be possible to build version tracking into existing ORMs such as Propel.