Deleting dag version record deletes task instance record

[dstandish]

Body

This is due to foreign key on delete cascade.

Probably better to set null?

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.

[uranusjr]

Or maybe we don’t actually delete the version? Like dags, we can do soft deletion instead.

[jedcunningham]

@dstandish can you expand on why this is a problem? Seems reasonable to me that we want to keep the dagversion/serdag for tis we have in the system... And while we can soft delete, just not sure its worth the complexity.

[sunank200]

@dstandish can you expand on why this is a problem? Seems reasonable to me that we want to keep the dagversion/serdag for tis we have in the system... And while we can soft delete, just not sure its worth the complexity.

I think Task instances are your single source of truth for what actually ran, when and with what result for a DAG. If you delete the DAG (or its version), you wipe out every TaskInstance that pointed at it. That means no more execution history for those runs. Is this the right behaviour for the user?