Pagerank is a like a markov chain - you iterate the same dataset over and over until you're happy with the result. If 20 is good enough, its good enough. Good

Pagerank is a like a markov chain - you iterate the same dataset over and over until you're happy with the result. If 20 is good enough, its good enough. Good explanation here: http://www.iterativemapreduce.org/samples.html#Pagerank http://www.iterativemapreduce.org/samples.html#Pagerank Whereas if you include signals from multiple sources, the joins are each one MR job, never mind the calculations.