Hi all,
I`m a beginner in building recommendation system. I have a very simple question, when we use mahout to do a CF recommendation, for example we use the basic user-based recommendation, is the similarity between 2 users(or the neighbourhood of one user) pre-computed or computed when the specific recommendation is performed? I found when I run the examples in mahout, the recommendation seems to be performed in the latter way which makes it quite ineffective. Since I`m doing a CF recommendation project, in which millions of users is involved so I hope I can make the CF recommendation in a more effective way.
