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https://issues.apache.org/jira/browse/GIRAPH-11?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13101710#comment-13101710
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Avery Ching commented on GIRAPH-11:
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Regarding the difference in hash based and hash rang based, it refers to how
the hash code is assigned to a partition. The application dev will implement
hashCode() for their vertex id and then the assignment of the hashCode() to a
partition can be hashed (i.e. hashCode() % # partitions) or range based
([0-a),[a-b)...etc). Hope that's more clear. Code will help. It's coming
soon, by mid next week I hope.
> Improve the graph distribution of Giraph
> ----------------------------------------
>
> Key: GIRAPH-11
> URL: https://issues.apache.org/jira/browse/GIRAPH-11
> Project: Giraph
> Issue Type: Improvement
> Reporter: Avery Ching
> Assignee: Avery Ching
>
> Currently, Giraph assumes that the data from the VertexInputFormat is sorted.
> If the user data is not sorted by the vertex id, they must first run a
> MapReduce or Pig job to generate a sorted dataset. This is often a bit
> inconvenient.
> Giraph graph partitioning is currently range based and there are some
> advantages and disadvantages of this approach. The proposal of this JIRA
> would be to allow for both range and hash based partitioning and provide more
> flexibility to the user.
> Design goals for the graph distribution:
> * Allow vertices to be unordered or unordered
> * Ability to repartition
> * Select the partitioning scheme based on user needs (i.e. hash or range
> based)
> * Ability to provide user-specific hints about partitions
> Hash-based partitioning
> * Good vertex balancing across ranges for random data
> * Bad at vertex id locality
> Range-based partitioning
> * Good at vertex id locality
> * Ability to split ranges easily
> * Can cause hotspots for hot ranges
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