Since you need to use a graph database analytics engine, you might be interested in Faunus. This is their description:
Faunus is a Hadoop-based graph analytics engine for analyzing graphs represented across a multi-machine compute cluster.
I know of it because I keep and eye on their graph database, Titan, which integrates nicely with Tinkerpop, but I have not used it (Faunus).
So by using Faunus you can also have a graph backend which IMO goes hand in hand with what you want to do.