Given a directory of files with the following structure: line number, tab character, string:
Example:
1abialkjfjkaoasdfjksdlkjhqweroij
2kadfjhuwqounahagtnbvaswslmnbfgy
3kjfteiomndscxeqalkzhtopedkfsikj
You want to send each line as one record to your Mapper. Which InputFormat should you use to
complete the line: conf.setInputFormat (____.class) ; ?

A.
SequenceFileAsTextInputFormat

B.
SequenceFileInputFormat

C.
KeyValueFileInputFormat

D.
BDBInputFormat

Explanation:
Note:
The output format for your first MR job should be SequenceFileOutputFormat – this will store the
Key/Values output from the reducer in a binary format, that can then be read back in, in your
second MR job using SequenceFileInputFormat.

Reference: How to parse CustomWritable from text in Hadoop
http://stackoverflow.com/questions/9721754/how-to-parse-customwritable-from-text-in-hadoop
(see answer 1 and then see the comment #1 for it)