Use case of dummy operator

Question

I was learning apache airflow and found that there is an operator called DummyOperator. I googled about its use case, but couldn't find anything that I can understand. Can anyone here please discuss its use case?

Answer 1

Operator that does literally nothing. It can be used to group tasks in a DAG.

https://airflow.apache.org/_api/airflow/operators/dummy_operator/index.html

as far as I know, at least to two case:

• test purpose. in dags, the dummy operation just between upstream and downstream, later, you can replace the true operator.
• Workflow purpose: BranchPythonOperator work with DummyOperator. If you want to skip some tasks, keep in mind that you can’t have an empty path, if so make a dummy task. https://airflow.apache.org/concepts.html#workflows

Answer 2

dummy_operator is used in BranchPythonOperator where we decide next task based on some condition.

For example:

                  -> task C->task D

 task A -> task B                      -> task F
                   ->  task E(Dummy)

So let's suppose we have some condition in task B which decides whether to follow [task C->task D] or task E(Dummy) to reach task F.

Since we cannot leave else condition empty we have to put dummy operator which does nothing just skip or bypass.