I want to store large number of data ppints for user actions, like likes, tags etc (I have plans for both e-commerce and document management).
With the data points, I want to support functions such as
By production-ready, real-time; I mean that I can enter data points and make queries at the same time, the server will take care of answering queries and updating scores by itself.
I searched around the interwebs and the solutions that come up are either of:
For recommenders, Mahout has a non-distributed recommender implementation that does not use Hadoop. In fact, this is the only part that is real-time; the Hadoop-based parts are not.
I think there is little learning curve to it; see here and here for a pretty complete writeup.
Mahout in Action chapters 2-5 cover this quite well too.