Jerry Chen created MAPREDUCE-4868:
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Summary: 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
Currently, the Mapper class allows advanced users to override "public void
run(Context context)" method for more control over the map 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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