- All Implemented Interfaces:
- org.apache.hadoop.io.Writable
public abstract class TaggedMapOutput
extends java.lang.Object
implements org.apache.hadoop.io.Writable
This abstract class serves as the base class for the values that
flow from the mappers to the reducers in a data join job.
Typically, in such a job, the mappers will compute the source
tag of an input record based on its attributes or based on the
file name of the input file. This tag will be used by the reducers
to re-group the values of a given key according to their source tags.