Rolling upgrade paranoia: what if you are updating from one version of Riak to another that has the same feature, but the re module compiles to a slightly different format? (say, changes between Erlang releases) Then you would send that to a node and it would probably crash over there. Since it's opaque, I tried to make no assumptions.  It kind of sucks. If you have a good argument to switch to a single re compilation, I'm all ears. It would be nice to do it only once.