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https://issues.apache.org/jira/browse/MAPREDUCE-4868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13528664#comment-13528664
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Jerry Chen commented on MAPREDUCE-4868:
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It showed to me that Spring Batch is another batch processing infrastructure.
While we are seeking solve the problem under the context of MapReduce as well
as enpower the map reduce in a reasonable manner, other than simply hook
totally to another batch processing thing.
> Allow multiple iteration for map
> --------------------------------
>
> Key: MAPREDUCE-4868
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4868
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: mrv2
> Affects Versions: 3.0.0, 2.0.3-alpha
> Reporter: Jerry Chen
> Fix For: 3.0.0, 2.0.3-alpha
>
> Original Estimate: 168h
> Remaining Estimate: 168h
>
> Currently, the Mapper class allows advanced users to override "public void
> run(Context context)" method for more control over the execution of the
> mapper, while Context interface limit the operations over the data which is
> the foundation of "more control".
> One of use cases is that when I am considering a hive optimziation problem, I
> want to go two passes over the input data instead of using a another job or
> task ( which may slower the whole process). Each pass do the same thing but
> with a different parameters.
> This is a new paradigm of Map Reduce usage and can be archived easily by
> extend Context interface a little with the more control over the data such as
> reset the input.
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