What does 'scale' mean :) ? Solving graph problems are best done in-memory with a big machine (RAM!), otherwise you are an order of magnitude slower (at least)

What does 'scale' mean :) ? Solving graph problems are best done in-memory with a big machine (RAM!), otherwise you are an order of magnitude slower (at least) if you try to distribute. But if you really have no choice I would have a look if some of the graph databases has a good distributed model. My gut feeling tells me that even a bad approach there is faster than spark ...