Blog On Map-Reduce

http://blog.matthewrathbone.com/2013/02/20/real-world-hadoop---implementing-a-left-outer-join-in-hive.html

http://www.thecloudavenue.com/2014/05/user-recomdations-with-big-data-1.html

http://www.bidn.com/blogs/cprice1979/ssas/4283/mapreduce-ninja-moves-combiners-shuffle-amp-doing-a-sort