Answer: none

The question asks which Auto Loader schema evolution mode **keeps the stream running** while **ignoring new columns**. **Correct Answer: D — `none`** **Why `none` is correct:** - In `none` mode, Auto Loader **does not evolve the schema**. - Any **new columns are ignored**, and the stream **does not fail**. - This is ideal when you want schema stability and don’t care about newly arriving fields. - This mode is commonly used when you **explicitly provide a schema**, which matches many production scenarios. **Why the other options are wrong:** - **A: dropNewColumns** – Not a valid Auto Loader mode. - **B: addNewColumns** – The default mode, but the stream **fails first** when new columns appear, even though they are added to the schema. - **C: ignoreNewColumns** – Not a supported mode. - **E: failOnNewColumns** – Immediately fails the stream and requires manual intervention. **Critical thinking tip:** If uninterrupted streaming is your priority and new fields are irrelevant to downstream consumers, `none` is the safest choice.

Author: LeetQuiz Editorial Team