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https://issues.apache.org/jira/browse/MAPREDUCE-1449?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aaron Kimball resolved MAPREDUCE-1449.
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Resolution: Won't Fix
Sqoop has been removed from MapReduce; issue moved to
http://github.com/cloudera/sqoop/issues#issue/2
> Sqoop Documentation about --split-by column has to be unique key seems to be
> wrong
> ----------------------------------------------------------------------------------
>
> Key: MAPREDUCE-1449
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1449
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: contrib/sqoop
> Affects Versions: 0.20.1
> Reporter: mingran wang
>
> http://archive.cloudera.com/docs/sqoo...
> The document above shows that " To guarantee correctness of your input, you
> must select an ordering column for which each row has a unique value. If
> duplicate values appear in the ordering column, the results of the import are
> undefined, and Sqoop will not be able to detect the error."
> I read the source code for sqoop, it seems that the column to split by
> doesn't have to be a unique key. Plus, when the primary key is a composite
> key, the sqoop code only takes the first column of the composite key which in
> most cases is not unique key anyways.
> I also checked the output when non-unique key is used to split, there is
> nothing wrong with the result.
> I am wondering if the document is wrong, or there is some hidden trickiness
> that I am not aware of.
> I am using sqoop 20.1.
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