Benjamin Heitmann commented on GIRAPH-170:

Thanks guys for your comments!

Paolo: I will take a look at Jena RIOT for inferencing. 

Sebastian: I did not know that it is possible to assign one mapper to each core 
in Hadoop, I will try that for sure. Also, my algorithm does only use a part of 
the graph when it runs. So that might be the easiest explanation for the 
observed behavior. 

Claudio: Thanks for the suggestion, I will further investigate the issue, and 
provide an update when I know whats going on. 
> Workflow for loading RDF graph data into Giraph
> -----------------------------------------------
>                 Key: GIRAPH-170
>                 URL: https://issues.apache.org/jira/browse/GIRAPH-170
>             Project: Giraph
>          Issue Type: New Feature
>            Reporter: Dan Brickley
>            Priority: Minor
> W3C RDF provides a family of Web standards for exchanging graph-based data. 
> RDF uses sets of simple binary relationships, labeling nodes and links with 
> Web identifiers (URIs). Many public datasets are available as RDF, including 
> the "Linked Data" cloud (see http://richard.cyganiak.de/2007/10/lod/ ). Many 
> such datasets are listed at http://thedatahub.org/
> RDF has several standard exchange syntaxes. The oldest is RDF/XML. A simple 
> line-oriented format is N-Triples. A format aligned with RDF's SPARQL query 
> language is Turtle. Apache Jena and Any23 provide software to handle all 
> these; http://incubator.apache.org/jena/ http://incubator.apache.org/any23/
> This JIRA leaves open the strategy for loading RDF data into Giraph. There 
> are various possibilites, including exploitation of intermediate 
> Hadoop-friendly stores, or pre-processing with e.g. Pig-based tools into a 
> more Giraph-friendly form, or writing custom loaders. Even a HOWTO document 
> or implementor notes here would be an advance on the current state of the 
> art. The BluePrints Graph API (Gremlin etc.) has also been aligned with 
> various RDF datasources.
> Related topics: multigraphs https://issues.apache.org/jira/browse/GIRAPH-141 
> touches on the issue (since we can't currently easily represent fully general 
> RDF graphs since two nodes might be connected by more than one typed edge). 
> Even without multigraphs it ought to be possible to bring RDF-sourced data
> into Giraph, e.g. perhaps some app is only interested in say the Movies + 
> People subset of a big RDF collection.
> From Avery in email: "a helper VertexInputFormat (and maybe 
> VertexOutputFormat) would certainly [despite GIRAPH-141] still help"

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