[MAPREDUCE-4507] IdentityMapper is being triggered when the type of the Input Key at class level and method level has a conflict

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.0.3
• Component/s: mrv1

Environment

linux ubuntu

• Assignee: Unassigned
• Reporter: Bejoy KS
• Created: 02/Aug/12 22:39
• Updated: 03/Aug/12 11:07

Description

If we use the default InputFormat (TextInputFormat) but specify the Key type in mapper as IntWritable instead of Long Writable. The framework is supposed throw a class cast exception.Such an exception is thrown only if the key types at class level and method level are the same (IntWritable). But if we provide the Input key type as IntWritable on the class level but LongWritable on the method level (map method), instead of throwing a compile time error, the code compliles fine . In addition to it on execution the framework triggers Identity Mapper instead of the custom mapper provided with the configuration. In this case the 'mapreduce.map.class' in job.xml shows mapper as Custom Mapper itself , it should show IdentityMapper in cases where IdentityMapper is triggered to avoid confusion and easy debugging.