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Date: Fri, 3 Feb 2012 10:44:47 +0100
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Subject: multi-graph support in giraph
From: =?UTF-8?B?QW5kcsOpIEtlbHBl?= <efeshundertelf@googlemail.com>
To: giraph-user@incubator.apache.org
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Hi list,

in my current usage of giraph I ran into the limitation that the API is cen=
tered
around simple graphs but in many applications you are actually dealing with
multi-graphs. One simple example is a road network, where there can be n ed=
ges
between 2 vertices. For my current program I could work around the "limitat=
ion"
by using an ArrayWritable as the edge value, which contains all edges that =
are
connectors to a neighbour vertex. That is however not the cleanest of all
approaches.

The pregel paper describes an API, where you work with iterators to all you=
r
outgoing edges and you then can access the vertex on the other end with a m=
ethod
call (see the impl of Shortest Path in the paper). That kind of API would
totally allow having multiple edges connecting the same two vertices direct=
ly
while the current API with getEdgeValue(vertexId) does not. What is the cur=
rent
view on this, is that a feature, that would be welcome? Should I open a JIR=
A
for the discussion? Am I overlooking something?

Thanks!

Andr=C3=A9