The following table describes the options for defining a reducer transformation:
| Option | Definition |
|---|---|
| Transformation |
Specify the transformation that will perform the reducer functions for this job by entering its path or clicking Browse. You can use any internal variable to specify the path. For example, if you select a transformation that is located in the same folder as the current transformation, you can use the ${Internal.Entry.Current.Directory} internal variable to define the path. If you are working with a repository, specify the name of the transformation in your repository. If you are not working with a repository, specify the XML file name of the transformation on your system. Note: Transformations previously specified by reference are automatically converted
to be specified by name within the Pentaho Repository.
|
| Input step name | Specify the name of the step that receives reducing data from Hadoop. It must be a MapReduce Input step. |
| Output step name | Specify the name of the step that passes reducing output back to Hadoop. It must be a MapReduce Output step. |
| Use single threaded transformation engine | Select to indicate the Single Threaded transformation execution engine should be used to execute the reducer transformation. If not selected, the normal multi-threaded transformation engine will be used. The Single Threaded transformation execution engine reduces overhead when processing many small groups of output. |