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From Claudio Martella <>
Subject Re: the slides for my talk @ FOSDEM
Date Tue, 07 Feb 2012 21:21:05 GMT
Hi Sebastian,

thanks for your feedback on the slides.

As a matter of fact I'm aware of the pegasus matrix-based optimization
as of the shimmy technique by Jimmy Lin. I thought that this kind of
technique is general enough for all iterative graph algorithms, not
just PR, and mostly using the naive algorithm would just help me out
explaining the presentation. Messaging the adjacent vertices from the
Mapper by iterating over them and emitting (otherVertex, myPartialPR)
maps easily to our messaging paradigm. I'll maybe make it more clear
in the next presentation.


On Mon, Feb 6, 2012 at 2:54 PM, Sebastian Schelter <> wrote:
> Hi Claudio,
> nice job with the slides! I have only one small point to criticize:
> When PageRank is implemented with MapReduce, it's not necessary to have
> the graph passed through in each iteration. Mahout for example uses
> power iterations where the adjacency matrix is multiplied by the
> pagerank vector and only that vector has to be sent over the network.
> Pegasus uses a similar approach.
> /s
> On 06.02.2012 12:24, Claudio Martella wrote:
>> Hello guys,
>> for those interested, here are the "slides" for my talk at FOSDEM.
>> The event was very nice, a tight community and a great interest in
>> Giraph. Isabel Drost, one of the organizers of Berlin Buzzwords,
>> invited the talk there. Jakob, are you still planning to talk there?
>> Maybe we can split Kafka/Giraph talks?
>> Best,
>> Claudio

   Claudio Martella

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