How to limit concurrent executions of a task during a backfill?

[Lance N.]

This is a DAG during a backfill run. Scheduling is random, which is almost find. I would like to limit each task (row) to only run one day at a time. Otherwise random scheduling is great. I'm already using the Pool feature for groups of tasks (each task reads from a table on one of several MySQL instances, so each instance gets one Pool).

These are the concurrency settings:

    max_active_runs=1,
    concurrency=3

Is there a specific limit to the number of concurrent executions of a particular task? Here you can see that two days of the same task are running simultaneously:

Thanks,

Lance Norskog