Building a Real-Time Recommendation Engine

I tried Neo4j a while back for recommendations and calculating similarities between users but when running against our full dataset got too many OutOfMemory exceptions. Ended up with a Mahout / Spark solution. It's an awesome graph db though - can find many other uses for it.

Anybody tried OrientDB for recommendation engine?

What a ridiculous title. Compare: &quot;building a hardwood coffee table with woodworking&quot;<p>Gotta get those keywords in for clicks