MapReduce Output

The MapReduce Output step defines the key/value pairs for Hadoop output.

The output of this step becomes the Hadoop output. How Hadoop uses that output depends on how you configured the transformation.

• If this step is used in a Mapper transformation type and a combiner and/or reducer is configured, the output becomes the input pairs for the combiner and/or reducer.

• If this step is used in a Mapper transformation type and no combiner or reducer is configured, the output is passed using the submitting Hadoop job’s format.

• If this step is used in a Combiner transformation type and a reducer is configured, the output becomes the input pairs for the reducer.

• If this step is used in a Combiner transformation type and no reducer is configured, the output is passed using the submitting Hadoop job’s format.

• If this step is used in a Reducer transformation type, the output is passed using the submitting Hadoop job’s format.

The data type for keys and values must be defined before this step.

Options

Option	Description
Step name	Specifies the unique name of the step on the canvas. You can place the step on the canvas multiple times; however, it represents the same step each time.
Key field	The Hadoop output field that represents the MapReduce key.
Value field	The Hadoop output field that represents the MapReduce value.

Metadata injection support

All fields of this step support metadata injection. You can use it with ETL metadata injection to pass metadata to your transformation at runtime.