That's only a challenge for a url shortener if it's going to need to scale to an enormous number of users. I think that's a good example of one of those "leave

That's only a challenge for a url shortener if it's going to need to scale to an enormous number of users. I think that's a good example of one of those "leave it for when you can't just make your one-machine more powerful or optimise your code more" situations.