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Date: Wed, 19 Sep 2012 15:04:45 +0800
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Subject: Re: pagerank NullPointerException
From: Sandy Ding <sandy.dingxin@gmail.com>
To: user@hama.apache.org
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So I have to recompile the pagerank example?
Can I pass it as a parameter to the existing jar?

2012/9/19 Thomas Jungblut <thomas.jungblut@gmail.com>

> Hey,
>
> if you read closely:
>
> http://wiki.apache.org/hama/WriteHamaGraphFile#Google_Web_dataset_.28local_mode.2C_pseudo_distributed_cluser.29
>
> You find that there is a property called "hama.graph.repair":
>
>     // hama takes care that the graph is complete
>     pageJob.set("hama.graph.repair", "true");
>
> This basically sends messages along the known edges and adds vertices
> if there aren't any on the "other side".
>
> If this isn't to scalable for you, then a preprocessing mapreduce job
> is fine, where you emit the vertex id as key along with the complete
> edge list as value, also the edge keys with an empty value.
> In the reducer you should get either multiple complete lines or empty
> values.
> In the case you get only an empty value, you know that this vertex
> wasn't included in the dataset and you can repair by emitting it in
> the reducer as single line.
>
>
> 2012/9/19 Sandy Ding <sandy.dingxin@gmail.com>:
> > Hi, guys,
> >
> > The web-google dataset seems to miss some key sites, for example, there
> is
> > no entry starting with 111067.
> > This leads to weird NullPointerException. How do you fix this?
> >
> > Cheers,
> > Sandy
>

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