Don't use isinstance for latest runs statement in dag processing

[dstandish]

Body

in _RunInfo.calculate, we use isinstance cron partition timetable to figure out how to calculate latest run

this is not ideal. find a better solution. maybe add an attribtue to the timetable, or to the model, or come up with something else.

Committer

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[sanchalitorpe-source]

I took a look at _RunInfo.calculate and see how the logic currently branches based on timetable type.

Would the intended direction be for timetables themselves to expose something like a “latest run calculation strategy” (e.g. via a method or attribute), so _RunInfo doesn’t need to know about concrete timetable classes?

I’m trying to understand whether this responsibility should live on the timetable side vs the DAG/model side before digging deeper.

[Lee-W]

Hey, thank you for looking into it. It's actually part of #59115 and not yet part of airflow. @dstandish and I discussed a bit offline, and I'll take care of this one since we've been discussing the details of it. Thanks!

[sanchalitorpe-source]

Thanks for the clarification! Makes sense that this is tied to #59115. Appreciate the context.