[jira] [Commented] (CASSANDRA-4886) Remote ColumnFamilyInputFormat

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-4886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13488107#comment-13488107 ] 

Jonathan Ellis commented on CASSANDRA-4886:
-------------------------------------------

I'm skeptical that we need a separate InputFormat to handle this.  (See discussion on CASSANDRA-2388.)
                
> Remote ColumnFamilyInputFormat
> ------------------------------
>
>                 Key: CASSANDRA-4886
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4886
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Hadoop
>    Affects Versions: 1.1.6
>            Reporter: Scott Fines
>             Fix For: 1.1.6
>
>         Attachments: CASSANDRA-4886.patch
>
>
> As written, the ColumnFamilyInputFormat does not have a great deal of fault tolerance. 
> It only attempts to perform a read from a single replica, with an infinite timeout. If that replica is not available, then the Task fails, and must be retried on a different node.
> This is fine if the TaskTrackers are colocated with Cassandra nodes, but is very fragile when this is not possible. When the Tasktrackers are remote to cassandra, the same rules about clients should apply--there should be a strict (configurable) timeout, and the ability to retry requests on a different replica if at single request fails. 
> It seems obvious that we'd want to support both types of architecture; to do that, we should probably have a configuration which allows the user to specify his architecture choices explicitely.

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