# dagster-feedback

Tobias Pankrath

03/22/2023, 1:36 PM
Is there a way to notify dagster that an asset materialization is missing, e.g. I am writing it to s3 into a bucket that is set to delete everything older than x weeks -> dagster somehow recognizes that it has to rematerialize the asset.

Adam Bloom

03/22/2023, 1:40 PM
You can check the existence of the output with an asset reconciliation sensor


03/23/2023, 7:40 PM
hey @Tobias Pankrath we dont have anything built in that would allow for checking this. However, you could look into adding freshness policies to your assets. since your know the contents of the bucket gets deleted each week, adding a freshness policy would ensure that the asset gets run each week to regenerate the asset

Tobias Pankrath

03/24/2023, 8:21 AM
hi, thanks for the answer, but it's not really a solution. I wasn't thinking about regenerating it once it get's deleted, but once a downstream asset requires it for it's materialization. It's not really a problem I have now, I was just curious. Thanks!