[exekias]

Yes, this is the case as of today. It's important to get the up/down functions right.

The good thing is that this will probably be detected during the start phase, as data would fail to be backfilled.

We are thinking of ideas to improve this in the longer term, for example: * Having a dry-run mode where you check that the data present in the DB will stay valid after applying the up function * Optionally allow for this to happen, but "quarantine" the affected rows so they are no longer available in the new schema.