Rollback
========

The delivery framework contains rollback functionality to rollback the state of a table to a previous point. Also, the framework can be used to rollback a **group** of the tables to a previous point in time. This *group* is defined by all the child ``%delivery_load`` statements in for a single a ``parent.py`` run.

The framework checks the ``\layer\name\metadata\run.delta`` table to determine whether the latest run has been executed successfully. If this is not the case, the user can either manually rollback all the tables, or use the framework to rollback all tables to their previous state.

You can enable checking whether the previous job run has finished successfully by setting the ``check_previous_run_successful`` to True in the ``@delivery_load`` yaml. When this is set to True, the framework will check whether the previous run has been executed successfully. If this is not the case, the framework will raise an exception by default. Also, with ``check_previous_run_successful`` set to True, you can also set ``restore_automatically`` to True in ``@delivery_load``. This will automatically rollback all tables to their previous state when the previous run has not been executed successfully. This is useful when you want to make sure that the previous run has been executed successfully before starting a new run.

The rollback functionality can be configured via the ``@delivery_load`` yaml, However, the Python functions can also be called manually:
The function :py:func:`~adp.delivery.rollback.rollback_table` can be used to rollback a table to a previous point in time. The function :py:func:`~adp.delivery.rollback.rollback_job` can be used to rollback a group of tables to a previous point in time.