What is the result of attempting to add CHECK constraints to an existing Delta Lake table that has invalid records?

When adding CHECK constraints to an existing Delta Lake table that contains invalid records, the operation will fail due to existing violations of those constraints. Delta Lake enforces data integrity, and when you introduce constraints like CHECK, it verifies that all existing data meets these new conditions. If any records in the table violate these constraints, the system will not allow the operation to proceed, thus preventing any further issues related to data integrity.

This behavior is intentional as it ensures that the integrity of data is maintained, and users are made aware of any violations before they can enforce stricter rules on the data. Therefore, the user is prompted to resolve these violations before applying the constraints, safeguarding the quality and reliability of the dataset. In contrast, other options suggest scenarios where the operation might succeed or bypass checking, which would undermine Delta Lake's principles of data governance and integrity management.