Sorry ignore my explanation. It's wrong. https://github.com/apache/airflow/issues/8649 explains why `schedule_interval=timedelta(days=14), start_date=...`. is not the exactly the same as bi-weekly for an exact specified time. It also provide an example for daily.
On Wed, Jan 20, 2021 at 9:19 PM Elad Kalif <elad...@gmail.com> wrote: > > `schedule_interval=timedelta(days=14), start_date=...`. > > ash from what I've seen It doesn't give the same exact functionality > This is what I observed: > cron = schedule exactly on regardless of what happened with previous run > (mostly) > timedelta() = schedule after delta passed. However it's from end_date not > from start_date. > so schedule_interval=timedelta(days=14) means It will be scheduled 14 days > from end_date or the previous run. If we consider for example that the dag > takes 2 days to complete then the next one will be scheduled after 14 days > from end_date (= 16 days from start_date). > > This exact case is actually explained really well in the first issue > listed https://github.com/apache/airflow/issues/8649 using daily example > > On Wed, Jan 20, 2021 at 9:17 PM Kaxil Naik <kaxiln...@gmail.com> wrote: > >> >> `schedule_interval=timedelta(days=14), start_date=...`. >> >> >> That won't support every second Thursday for example >> >> On Wed, Jan 20, 2021 at 6:54 PM Ash Berlin-Taylor <a...@apache.org> wrote: >> >>> Running exactly every two weeks can be done by setting >>> `schedule_interval=timedelta(days=14), start_date=...`. >>> >>> Does this do what you need Elad? >>> >>> On 20 January 2021 18:12:36 GMT, Elad Kalif <elad...@gmail.com> wrote: >>>> >>>> >> In the example of a twice-a-month dag (not sure if it you have this >>>> use case too?) what do you expect the "data interval" (i.e. execution_date) >>>> to be? >>>> Yes we have this use case too. The execution date does matter because I >>>> want it to be bi-weekly for starting specific day and time >>>> so with the current implementation I expect to provide >>>> start_date=datetime(2021,1,19,20,5) & schedule_interval='2 weeks' >>>> >>>> Currently Airflow has 'hourly', 'daily' , 'weekly' - which doesn't >>>> allow us to set it. >>>> So a possible solution for this specific use case could be defining: >>>> repeat_every - integer that represents the frequency (1,2,3,... n) >>>> unit - str that provide the "gaps" (minutes, hours, days, weeks, >>>> months, years) >>>> Example: bi-weekly / twice a month can be: repeat_every = 2, unit = >>>> 'weeks' >>>> To get the 'hourly', 'daily' , 'weekly' functionality it >>>> just needs to set unit=1. >>>> >>>> By the way this is exactly what google calendar allows to set if you >>>> click on custom scheduling for a meeting. >>>> >>>> I'm still in favor of the python function approach as it should cover >>>> all cases and provide full control for the users. >>>> >>>> On Wed, Jan 20, 2021 at 7:20 PM Deng Xiaodong <xd.den...@gmail.com> >>>> wrote: >>>> >>>>> A quick thought (*maybe not making sense*): if *schedule_interval* accepts >>>>> a list of values, we may support much higher complexity. >>>>> >>>>> For example, I may want to schedule my jobs at every days' 04:05 AND >>>>> 02:31 , which cannot be expressed by single Cron pattern. Then I may want >>>>> to have *schedule_interval = ["5 4 * * *", "31 2 * * *"]*. >>>>> >>>>> Maybe I missed something or the idea doesn't make sense. Please let me >>>>> know. >>>>> >>>>> >>>>> XD >>>>> >>>>> On Wed, Jan 20, 2021 at 6:09 PM Ash Berlin-Taylor <a...@apache.org> >>>>> wrote: >>>>> >>>>>> Yes, we quite possibly could do this -- I'm trying to work out what >>>>>> the needs are here. >>>>>> >>>>>> In the example of a twice-a-month dag (not sure if it you have this >>>>>> use case too?) what do you expect the "data interval" (i.e. >>>>>> execution_date) >>>>>> to be? >>>>>> >>>>>> Or for this case does it not matter? >>>>>> >>>>>> -ash >>>>>> >>>>>> >>>>>> On Wed, 20 Jan, 2021 at 19:06, Elad Kalif <elad...@gmail.com> wrote: >>>>>> >>>>>> Another case that is mentioned in one of the issues is the ability to >>>>>> schedule a bi-weekly job (equivalent of bi-weekly meeting that you can >>>>>> set >>>>>> in a calendar) which is very much needed. >>>>>> >>>>>> Maybe this is unrealistic but I think the game changer is if it would >>>>>> be possible to let the users define their own logic and airflow will use >>>>>> it >>>>>> to schedule DAGs. >>>>>> My thought here is - if I can define the logic in a python function >>>>>> (regardless of what this logic is). Can't Airflow utilize it? >>>>>> >>>>>> On Wed, Jan 20, 2021 at 5:39 PM Ash Berlin-Taylor <a...@apache.org> >>>>>> wrote: >>>>>> >>>>>>> Hi everyone, >>>>>>> >>>>>>> I'd like to (re)start the discussion about a new feature I'd like to >>>>>>> add for Airflow 2.1, that I am loosely calling "improving >>>>>>> schedule_interval" (catchy name I know!) >>>>>>> >>>>>>> I have two main high-level goals in mind here: >>>>>>> >>>>>>> 1. To reduce the confusion around execution_date (specifically the >>>>>>> naming of the parameter!) - the whole start vs end discussion. >>>>>>> 2. To support more complex schedules. >>>>>>> >>>>>>> Previous thread on this point 1 here: >>>>>>> https://lists.apache.org/thread.html/2b12ae265795ff2e655a5161c972f5c7bbe60722a12849a0e2c5c55f%40%3Cdev.airflow.apache.org%3E, >>>>>>> (but I'm taking a bit of a step back from that to think if there's a >>>>>>> bigger >>>>>>> change we could make that encompases this) >>>>>>> >>>>>>> >>>>>>> I don't yet have a concrete plan, nor implementation in mind, but >>>>>>> I'd like to start collecting peoples "wish list" when it comes to >>>>>>> scheduling DAGS: >>>>>>> >>>>>>> - What do you wish you could express natively in terms of scheduling >>>>>>> your DAGs? (I.e. without using "hacks" such as date sensor/skip tasks at >>>>>>> start) >>>>>>> - What schedules do you wish you could express now, that you just >>>>>>> can't? >>>>>>> - Do you have good example workflows that give a good example of >>>>>>> where you want schedule at start? Follow up question: do you also want >>>>>>> this >>>>>>> to be different for different DAGs in your Airflow install? >>>>>>> >>>>>>> >>>>>>> Existing issues: >>>>>>> https://github.com/apache/airflow/issues/8649 "Add support for more >>>>>>> than 1 cron exp per DAG" >>>>>>> https://github.com/apache/airflow/issues/10194 "Ability to better >>>>>>> support odd scheduling time" >>>>>>> https://github.com/apache/airflow/issues/10449 "Dynamic Schedule >>>>>>> Intervals" >>>>>>> https://github.com/apache/airflow/issues/10123 "Job Schedule >>>>>>> Interval on 2nd & 4th Tuesday" >>>>>>> >>>>>>> I'll start: >>>>>>> >>>>>>> Case1: >>>>>>> >>>>>>> One example that came up recently in slack was an actual astronomer >>>>>>> wanting a DAG to run with a schedule of "@sunset"! This also brings up >>>>>>> the >>>>>>> subject of "running dags at interval start or end" >>>>>>> >>>>>>> Case2: >>>>>>> >>>>>>> I'd like to be able to run a daily process at the end of each week >>>>>>> day. I.e. to process data for Monday..Friday. The naive way of >>>>>>> expressing >>>>>>> this would be "0 0 * * MON-FRI", but that means that the dags would run >>>>>>> Tuesday, Wednesday ,Thursday ,Friday, Monday -- meaning Friday's data >>>>>>> isn't processed until Monday! >>>>>>> >>>>>>> My thoughts on this is we need to separate schedule interval (when >>>>>>> to run a task) from the period duration (i.e look at one days worth of >>>>>>> data). >>>>>>> >>>>>>> Thanks, >>>>>>> Ash >>>>>>> >>>>>>> >>>>>>> >>>>>>>
