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https://issues.apache.org/jira/browse/TEZ-3215?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15494569#comment-15494569
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Zhiyuan Yang commented on TEZ-3215:
-----------------------------------
Should we disallow user to use write(key, value) method in
KeyValueWriterWithBasePath? Using this method requires user to know what's the
current value of 'mapreduce.output.basename' which may be hard to track,
especially when we have parallel changes of it. Careless usage of this method
can cause data written to wrong places.
> Support for MultipleOutputs
> ---------------------------
>
> Key: TEZ-3215
> URL: https://issues.apache.org/jira/browse/TEZ-3215
> Project: Apache Tez
> Issue Type: Improvement
> Reporter: Ming Ma
> Assignee: Ming Ma
> Attachments: TEZ-3215-2.patch, TEZ-3215-3.patch, TEZ-3215.patch
>
>
> Here is the use case. A reducer might write its output to more than one file.
> The file name will be based on the mapper key. We don't know all possible
> keys ahead of time. In MR, MultipleOutputs provides such support. I couldn't
> find anything readily available in Tez.
> * Set up one DataSink per file ahead of time won't work as we don't know all
> possible keys.
> * Use MR MultipleOutputs directly from the Tez application processor. It
> isn't clear how to pass TaskInputOutputContext to MultipleOutputs.
> * Tez MROutput can create a DataSink based on the specified outputFormat. But
> it can't take MR MultipleOutputs.
> I end up modifying Tez MROutput with HashMap {{recordWriters}} to achieve
> this. If this is a solved problem, can anyone explain how to do it?
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