[ http://issues.apache.org/jira/browse/HADOOP-115?page=all ]
Runping Qi updated HADOOP-115:
------------------------------
Attachment: patch_115.txt.2006_05_16
My patch is attached.
Change highlights:
JobConf.java:
Added set/getMapOutputKey/ValueClass methods
Modified getOutputKeyComparatorClass
MapTask.java:
call getMapOutputKey/ValueClass instead of getOutputKey/ValueClass
MapReduce.java:
call getMapOutputKey/ValueClass instead of getOutputKey/ValueClass
MapOutputFile.java:
call getMapOutputKey/ValueClass instead of getOutputKey/ValueClass
I've run a job with a combiner, with UTF8 as the map output value class, and
CrawledDoc as the output value class.
The job completed successfully.
> Hadoop should allow the user to use SequentialFileOutputformat as the output
> format and to choose key/value classes that are different from those for map
> output.
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-115
> URL: http://issues.apache.org/jira/browse/HADOOP-115
> Project: Hadoop
> Type: Improvement
> Components: mapred
> Reporter: Runping Qi
> Assignee: Runping Qi
> Attachments: hadoop-115_ReduceTask.patch, hadoop-115_tk.patch,
> patch_115.txt.2006_05_16
>
> When map tasks write intermediate data out, they always use SequencialFile
> RecordWriter with key/value classes from the job object.
> When the reducers write the final results out, its output format is obtained
> from the job object. By default, it is TextOutputFormat, and no conflicts.
> However, if one wants to use SequencialFileFormat for the final results, then
> the key/value classes are also obtained from the job object, the same as the
> map tasks' output. Now we have a problem. It is impossible for the map
> outputs and reducer outputs use different key/value classes, if one wants the
> reducers generate outputs in SequentialFileFormat.
> A simple fix would be to add another two attributes to JobConf class:
> mapOutputLeyClass and mapOutputValueClass. That allows the user to have
> different key/value classes for the intermediate and final outputs.
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