re this: https://dagster.slack.com/archives/C01U954MEER/p1686073627696329 context: source data for the partition is only ready 3 days after the partition is "closed". I shifted the schedule to materialize it 3 days later, but during this time the partition shows up as missing in the UI (even though materializing it will result in an error) now I have an unpartitioned asset that depends on it, but using LastPartitionMapping points to the missing partition for the first 3 days until it is materialized.

Hm this is definitely an interesting use case, and it does potentially point to a missing concept in the dagster framework, where currently we assume that any partition is ready to be materialized as soon as it pops into existence. Another workaround (which isn't necessarily any better) would be to just set up the weekly_asset to be a

TimeWindowPartitionsDefinition(
    start_date=...,
    schedule_type=ScheduleType.WEEKLY,
    day_offset=3,
    fmt="%Y-%m-%d",
)

This would let you have your weekly partitions be shifted by 3 days, so they'd only pop into existence when they actually existed. The downside of this is that your partitions will be mislabeled (as they'll represent the time they came into existence rather than the data they actually contain)

hmmm I don't think this works as I expected. I just tried it, shifted my date back to july 12th, and the 2023-07-05 partition is still there, which would include this range:

TimeWindow(start=DateTime(2023, 7, 5, 0, 0, 0, tzinfo=Timezone('UTC')), end=DateTime(2023, 7, 12, 0, 0, 0, tzinfo=Timezone('UTC')))