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https://issues.apache.org/jira/browse/CASSANDRA-6268?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Piotr Kołaczkowski updated CASSANDRA-6268:
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    Attachment: 0001-DSP-2572-Adds-ability-to-set-target-DCs-where-a-Hado.patch

> Poor performance of Hadoop if any DC is using VNodes
> ----------------------------------------------------
>
>                 Key: CASSANDRA-6268
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6268
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Hadoop
>            Reporter: Piotr Kołaczkowski
>            Assignee: Piotr Kołaczkowski
>         Attachments: 
> 0001-DSP-2572-Adds-ability-to-set-target-DCs-where-a-Hado.patch
>
>
> Some customers are complaining about huge number of splits in Hadoop caused 
> by VNodes. Disabling vnodes only in Hadoop DC does not fix it, because splits 
> are generated from the results of describe_ring, which returns a huge number 
> of ranges. 
> The proposed fix:
> - allows for specifying the DCs the Hadoop job should be run
> - merges the consecutive ranges before generating Hadoop splits, so we don't 
> have artificial range splitting caused by vnodes in the other DCs



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