Based on what I've seen for some internal things, that's one claim I'd like to see support for. m/r on Riak has been an unmitigated disaster here for anything beyond incredibly trivial working sets.

I see you're irrationally proselytizing again.

We just saw you over in the programming languages thread, now you're here, refusing to confront the reality of how broken M/R is in Riak.

What monkey crawls around on your back to make you so confrontational and irrational?

I've never seen a Riak MR job over more than 3 million keys complete, on a 6-node SSD cluster. It might be possible, but you'd have to throw a lot more HW at it than the comparable Hadoop setup.