Once you have created the Mapper transformation, you are ready to include it in a Pentaho MapReduce job entry and build a MapReduce job.
Open a PDI job and drag the specifically-designed Pentaho MapReduce job entry onto the canvas. In addition to ordinary transformation work, this entry is designed to execute mapper/reducer functions within PDI. Again, no need to provide a Java class to achieve this.
Configure the Pentaho MapReduce entry to use the transformation as a mapper. Drag and drop a Start job entry, other job entries as needed, and result job entries to handle the output onto the canvas. Add hops to sequence the entries into a job that you execute in PDI.
The workflow for the job should look something like this.
The Pentaho MapReduce dialog box enables you to configure the Pentaho MapReduce entry.