You might want to run a mapping from a workflow so that you can run multiple mappings sequentially, make a decision during the workflow, or send an email notifying users of the workflow status. Or, you can develop a workflow that runs commands to perform steps before and after the mapping runs.
When a Mapping task runs a mapping configured to run in a Hadoop environment, do not assign the Mapping task outputs to workflow variables. Mappings that run in a Hadoop environment do not provide the total number of target, source, and error rows. When a Mapping task includes a mapping that runs in a Hadoop environment, the task outputs contain a value of zero (0).