jeffolsi commented on issue #8649:
URL: https://github.com/apache/airflow/issues/8649#issuecomment-622065472
> An immediate solution to your last sentence is to use timedelta. This is
also supported: `schedule_interval=timedelta(weeks=2)`.
It's not the same. When specifying cron exp you guaranty that tasks will be
fired when the time comes. If you use `timedelta(weeks=2)` you are risking that
a delay in running of one task will cause further delay in others as it always
look for 2 weeks difference than the last task
to explain lets use daily for simplicity:
2020-04-28 0 0 * * * - this will run every day:
2020-04-29 00:00:00
2020-05-01 00:00:00
Now lets say that airflow was down and the run of 2020-04-29 00:00:00
started to run on 2020-04-29 04:00:00, the next run will still be on 2020-05-01
00:00:00
On the other hand with:
2020-04-28 timedelta(days=1)
if the run of 2020-04-29 00:00:00 started to run on 2020-04-29 04:00:00, the
next run will still be on **2020-05-01 04:00:00** The whole schedule is shifted
because of the delay!
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