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https://issues.apache.org/jira/browse/PIG-162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12586508#action_12586508
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Shravan Matthur Narayanamurthy commented on PIG-162:
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Another issue that I mentioned in the call is that we don't have a
DoubleWritable, the writable counterpart for the java.lang.Double that can be
used as a key when we have a group statement. For ex.,
group A by $0;
If $0 is an Integer, while collecting this as the key, it would be efficient if
we converted $0 into IntWritable than wrap in a tuple and strip the tuple off
in the reduce side.
However, for some strange reason, Hadoop has the Writable versions for all the
scalar types that we are supporting except Double. It even has a MapWritable
for using Maps but it doesn't implement the Comparable interface.
Also Map presents another problem. As it is a nested structure and we need to
do a deep copy or clone in order to ensure correctness. Is there a better way
to handle maps as keys?
> Rework mapreduce submission and monitoring
> ------------------------------------------
>
> Key: PIG-162
> URL: https://issues.apache.org/jira/browse/PIG-162
> Project: Pig
> Issue Type: Sub-task
> Environment: This bug tracks works to rework the submission and
> monitoring interface to map reduce as described in
> http://wiki.apache.org/pig/PigTypesFunctionalSpec
> Reporter: Alan Gates
> Assignee: Alan Gates
> Attachments: split.png
>
>
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