Deleting a document or a collection leads to dead links in documents that refer to the deleted document/collection.
They need to be cleaned up manually.
Instead of cleaning up manually, having an option in Fauna that cleans up referencing fields automatically if the referencing field is optional(schema enforcement).
A special case is mandatory referencing fields. They can’t be simply cleaned up because in that case they violate the mandatory constraint. In that case, it could be helpful to offer a way to attach clean-up functions to fields that store the logic to deal with mandatory referencing fields.
Disclaimer: Cascading deletes were discussed already at different places. Creating a feature request for this for tracking purposes.