Mahout : Recommender System

https://mahout.apache.org/users/algorithms/recommender-overview.html

But to get the best out of our more modern aproach we'll need to think of the Recommender as a "model creation" component—supplied by Mahout's new spark-itemsimilarity job, and a "serving" component—supplied by a modern scalable search engine, like Solr.

1. Collect (user-id, item-id)
2. Mahout create (item-id, list-of-similar-items)
3. Query user history to get indicator collection (list-of-similar-items...)