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MAPREDUCE-6583. Clarify confusing sentence in MapReduce tutorial document. Contributed by Kai Sasaki.

This commit is contained in:
Akira Ajisaka 2015-12-21 00:16:14 +09:00
parent 0f82b5d878
commit 7995a6ea4d
2 changed files with 6 additions and 3 deletions
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3
hadoop-mapreduce-project/CHANGES.txt
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@ -692,6 +692,9 @@ Release 2.7.3 - UNRELEASED
MAPREDUCE-6549. multibyte delimiters with LineRecordReader cause
duplicate records (wilfreds via rkanter)
MAPREDUCE-6583. Clarify confusing sentence in MapReduce tutorial document.
(Kai Sasaki via aajisaka)
Release 2.7.2 - UNRELEASED
INCOMPATIBLE CHANGES

6
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/site/markdown/MapReduceTutorial.md
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@ -311,7 +311,7 @@ public void reduce(Text key, Iterable<IntWritable> values,
}
```
The `Reducer` implementation, via the `reduce` method just sums up the values, which are the occurence counts for each key (i.e. words in this example).
The `Reducer` implementation, via the `reduce` method just sums up the values, which are the occurrence counts for each key (i.e. words in this example).
Thus the output of the job is:
@ -348,7 +348,7 @@ Maps are the individual tasks that transform input records into intermediate rec
The Hadoop MapReduce framework spawns one map task for each `InputSplit` generated by the `InputFormat` for the job.
Overall, `Mapper` implementations are passed the `Job` for the job via the [Job.setMapperClass(Class)](../../api/org/apache/hadoop/mapreduce/Job.html) method. The framework then calls [map(WritableComparable, Writable, Context)](../../api/org/apache/hadoop/mapreduce/Mapper.html) for each key/value pair in the `InputSplit` for that task. Applications can then override the `cleanup(Context)` method to perform any required cleanup.
Overall, mapper implementations are passed to the job via [Job.setMapperClass(Class)](../../api/org/apache/hadoop/mapreduce/Job.html) method. The framework then calls [map(WritableComparable, Writable, Context)](../../api/org/apache/hadoop/mapreduce/Mapper.html) for each key/value pair in the `InputSplit` for that task. Applications can then override the `cleanup(Context)` method to perform any required cleanup.
Output pairs do not need to be of the same types as input pairs. A given input pair may map to zero or many output pairs. Output pairs are collected with calls to context.write(WritableComparable, Writable).
@ -848,7 +848,7 @@ In the following sections we discuss how to submit a debug script with a job. Th
##### How to distribute the script file:
The user needs to use [DistributedCache](#DistributedCache) to *distribute* and *symlink* thescript file.
The user needs to use [DistributedCache](#DistributedCache) to *distribute* and *symlink* to the script file.
##### How to submit the script: