Hm, I haven't. This suggests that Mahout might not work well for datasets on the scale we're dealing with (working toward 1 billion membership rows): http://lu

Hm, I haven't. This suggests that Mahout might not work well for datasets on the scale we're dealing with (working toward 1 billion membership rows): http://lucene.472066.n3.nabble.com/Mahout-not-giving-recommendations-with-large-data-sets-td641249.html http://lucene.472066.n3.nabble.com/Mahout-not-giving-recomme... But that's also an older article, and things might be better. Mahout might be worth checking out.