8ee2d4e0_kasper_s_source__What_
[How?] DataCleaner does support transformers that yield multiple (or even zero) output records. To archieve this, you can inject an OutputRowCollector instance into the Transformer: public class MyTransformer implements Transformer<...> { @Inject @Provided OutputRowCollector collector; public void transform(InputRow row) { // output two records, each with two new values collector.putValues("foo", "bar"); collector.putValues("hello", "world"); } } Side-note - Users of Hadoop might recognize the OutputRowCollector as similar to mappers in Map-Reduce. Transformers, like mappers, are in deed quite capable of executing in parallel. [What?] 
In a more advanced edition of the same transformer, I wanted to support multiple output records.
kasper's source
What?