[MAPREDUCE-1772] Hadoop streaming doc should not use IdentityMapper as an example

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.22.0
• Component/s: contrib/streaming, documentation
• Hadoop Flags: Reviewed
• Assignee: Amareshwari Sriramadasu
• Reporter: Marco Nicosia
• Created: 17/Oct/08 23:08
• Updated: 29/Oct/10 02:03
• Resolved: 19/Jul/10 10:31

Description

From the URL http://hadoop.apache.org/core/docs/current/streaming.html

This example doesn't work:

You can supply a Java class as the mapper and/or the reducer. The above example is equivalent to:

$HADOOP_HOME/bin/hadoop jar $HADOOP_HOME/hadoop-streaming.jar \
-input myInputDirs \
-output myOutputDir \
-mapper org.apache.hadoop.mapred.lib.IdentityMapper \
-reducer /bin/wc

This will produce the following exception:

java.io.IOException: Type mismatch in key from map: expected org.apache.hadoop.io.Text, recieved org.apache.hadoop.io.LongWritable