So hang on, what exactly is a recommendation engine?<p>They give examples of LinkedIn (<i>people you may know</i>) and Amazon (presumably <i>other people who bought this</i>, <i>so-and-so's list of such-a-subject books</i>).<p>That makes sense, though the segment of businesses that may actually benefit seems limited. Social stuff, sure. Most of us? What's the minimum recommendable-entity/category-or-user threshold that this makes sense for? Is success with these sorts of engines merely a reflector of poor UI design in your normal UX? (Of the above examples, the first seems very unidimensional - in that it's basically a simple graph distance - and the latter also rather rudimentary and often irrelevant).<p>So what exactly is this thing providing? Graph analysis? I think not. It reads more like some kind of raw timestamped user behavioural event data processing to infer relationships between users or products they interact with. Reading through the docs it seems this is a layer on top of Apache Pig (<a href="https://pig.apache.org/" rel="nofollow">https://pig.apache.org/</a>) - <i>a high-level language for expressing data analysis programs, coupled with infrastructure for evaluating these programs</i>. I think clarity in explaining this thing could be improved, particularly selling clearly what a recommendation is and when its useful. Using phrases like "award winning" doesn't help.<p>PS. Why all the downvotes? Sheesh.