Yes! It does work with Depends_on_past=True. -s On Thu, Oct 13, 2016 at 10:28 AM, Boris Tyukin <[email protected]> wrote:
> thanks so much, Sid! just a follow up question on "Only_Run_Latest" - will > it work with depend_on_past = True? or it will assume that DAG is used > False? > > On Thu, Oct 13, 2016 at 1:11 PM, siddharth anand <[email protected]> > wrote: > > > Boris, > > > > *Question 1* > > Only_Run_Latest is in master - > > https://github.com/apache/incubator-airflow/commit/ > > edf033be65b575f44aa221d5d0ec9ecb6b32c67a. > > That will solve your problem. > > > > Releases come out one a quarter sometimes once every 2 quarters, so I > would > > recommend that you run off master or off your own fork. > > > > You could also achieve this yourself with the following code snippet. It > > uses a ShortCircuitOperator that will skip downstream tasks if the DagRun > > being executed is not the current one. It will work for any schedule. The > > code below has essentially been implemented in the LatestOnlyOperator > above > > for convenience. > > > > def skip_to_current_job(ds, **kwargs): > > > > now = datetime.now() > > > > left_window = kwargs['dag'].following_schedule(kwargs['execution_ > > date']) > > > > right_window = kwargs['dag'].following_schedule(left_window) > > > > logging.info(('Left Window {}, Now {}, Right Window {}' > > ).format(left_window,now,right_window)) > > > > if not now <= right_window: > > > > logging.info('Not latest execution, skipping downstream.') > > > > return False > > > > return True > > > > > > t0 = ShortCircuitOperator( > > > > task_id = 'short_circuit_if_not_current, > > > > provide_context = True, > > > > python_callable = skip_to_current_job, > > > > dag = dag > > > > ) > > > > > > -s > > > > > > On Thu, Oct 13, 2016 at 7:46 AM, Boris Tyukin <[email protected]> > > wrote: > > > > > Hello all and thanks for such an amazing project! I have been > evaluating > > > Airflow and spent a few days reading about it and playing with it and I > > > have a few questions that I struggle to understand. > > > > > > Let's say I have a simple DAG that runs once a day and it is doing a > full > > > reload of tables from the source database so the process is not > > > incremental. > > > > > > Let's consider this scenario: > > > > > > Day 1 - OK > > > > > > Day 2 - airflow scheduler or server with airflow is down for some > reason > > > ((or > > > DAG is paused) > > > > > > Day 3 - still down(or DAG is paused) > > > > > > Day 4 - server is up and now needs to run missing jobs. > > > > > > > > > How can I make airflow to run only Day 4 job and not backfill Day 2 and > > 3? > > > > > > > > > I tried to do depend_on_past = True but it does not seem to do this > > trick. > > > > > > > > > I also found in a roadmap doc this but seems it is not made to the > > release > > > yet: > > > > > > > > > Only Run Latest - Champion : Sid > > > > > > • For cases where we need to only run the latest in a series of task > > > instance runs and mark the others as skipped. For example, we may have > > job > > > to execute a DB snapshot every day. If the DAG is paused for 5 days and > > > then unpaused, we don’t want to run all 5, just the latest. With this > > > feature, we will provide “cron” functionality for task scheduling that > is > > > not related to ETL > > > > > > > > > My second question, what if I have another DAG that does incremental > > loads > > > from a source table: > > > > > > > > > Day 1 - OK, loaded new/changed data for previous day > > > > > > Day 2 - source system is down (or DAG is paused), Airflow DagRun failed > > > > > > Day 3 - source system is down (or DAG is paused), Airflow DagRun failed > > > > > > Day 4 - source system is up, Airflow Dagrun succeeded > > > > > > > > > My problem (unless I am missing something), Airflow on Day 4 would use > > > execution time from Day 3, so the interval for incremental load would > be > > > since the last run (which was Failed). My hope it would use the last > > > _successful_ run so on Day 4 it would go back to Day 1. Is it possible > to > > > achieve this? > > > > > > I am aware of a manual backfill command via CLI but I am not sure I > want > > to > > > use due to all the issues and inconsistencies I've read about it. > > > > > > Thanks! > > > > > >
