How to depend on all partitions to date of an asset?

[elliottlawrence]

I have an asset that's partitioned by day, let's call it events. I also have an asset that computes certain summary metrics based on events, let's call it aggregated_metrics.

I also want to partition aggregated_metrics by day, but I want each partition to depend on all previous partitions of events up to and including that day.

I'm not quite sure how to accomplish this in Dagster. TimeWindowPartitionsMapping seems to only allow start and end date offsets, not a fixed start date, and AllPartitionMapping will include partitions after the date that I want. Is there a straightforward way to do this?

[OwenKephart]

Hi @elliottlawrence! While there's not a first-class way to do this, it is possible to set the start_offset of your TimeWindowPartitionMapping to a large enough value such that it will cover all previous partitions. i.e. if you are using DailyPartitionsDefinition, you could set the partition mapping to be TimeWindowPartitionMapping(start_offset=-365*20) to capture the previous 20 years of partitions. Bounding that (presumably) too-large range to the real start date will happen automatically.