We know that prior to Mapper phase the files are split and the RecordReader starts working to emit a input to the Mapper. My question is whether the reducer uses a RecordReader class to read the data emitted by the mapper?
because reducer takes input too!! Please Explain!!!
Overview of the mapreduce steps is as follows
1) InputFormat :
- Validates the Input.
- Splits the input files.
- Gives Record Reader Implementation to give input to Mapper.
2)Mapper Phase
3)Shuffle and Sort Phase
4)Reducer Phase
5) OutputFormat
- Validates the Output Specification.
- Provides Record Writer Implementation used to write the output files.
Reducer does not use record reader...