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! > > >
