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From Steve Loughran <ste...@apache.org>
Subject Re: Pregel
Date Tue, 08 Sep 2009 10:36:30 GMT
Ted Dunning wrote:
> You would be entirely welcome in Mahout.   Graph based algorithms are key
> for lots of kinds of interesting learning and would be a fabulous thing to
> have in a comprehensive substrate.
> I personally would also be very interested in learning more about about what
> sorts of things Pregel is doing.  It is relatively easy to build simple
> graph algorithms on top of Map-reduce, but these algorithms typically
> require a map-reduce iteration to propagate information.  Good algorithms
> for that architecture have exponential propagation so that you don't need a
> huge number of iterations.  It smelled like Pregel was doing something much
> more interesting.

Exactly, it is not pushing bits of the graph around. Instead it has 
partitioned the graph to different machines, and is pushing the work out 
to the relevant bits of the graph, a sort of GraphReduce. I believe, not 
having seen the code myself :)

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