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https://issues.apache.org/jira/browse/MAPREDUCE-6854?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gil Vernik updated MAPREDUCE-6854:
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Summary: Each map task should create a unique temporary name that includes
an object name (was: Each map task should create a unique temporary name that
includes object name)
> Each map task should create a unique temporary name that includes an object
> name
> --------------------------------------------------------------------------------
>
> Key: MAPREDUCE-6854
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6854
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: distcp
> Reporter: Gil Vernik
>
> Consider an example: a local file "/data/a.txt" need to be copied into
> swift://container.service/data/a.txt
> The way distcp works is that first it will upload "/data/a.txt" into
> swift://container.mil01/data/.distcp.tmp.attempt_local2036034928_0001_m_000000_0
> Upon completion distcp will move
> swift://container.mil01/data/.distcp.tmp.attempt_local2036034928_0001_m_000000_0
> into swift://container.mil01/data/a.txt
> The temporary file naming convention assumes that each map task will
> sequentially create objects as swift://container.mil01/.distcp.tmp.attempt_ID
> and then rename them to the final names. Such flow is problematic in the
> object stores, where it usually advised not to create, delete and create
> object under the same name.
> This JIRA propose to add a configuration key indicating that temporary
> objects will also include object name as part of their temporary file name,
> For example
> "/data/a.txt" will be uploaded into
> "swift://container.mil01/data/.distcp.tmp.attempt_local2036034928_0001_m_000000_0/a.txt"
> or
> "swift://container.mil01/data/a.txt/.distcp.tmp.attempt_local2036034928_0001_m_000000_0"
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