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https://issues.apache.org/jira/browse/GIRAPH-170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13260512#comment-13260512
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Benjamin Heitmann commented on GIRAPH-170:
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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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