An Auto Loader stream that feeds a Unity Catalog-governed Delta table failed in the middle of the night after processing part of the incoming file batch. In the morning, the on-call engineer restarts the stream from the same notebook, pointing at the same input directory, checkpoint location, and target table. What does Auto Loader guarantee after the restart?

1. A. It resumes where it left off: files already recorded in checkpoint state are not reprocessed, preserving exactly-once semantics ✓ A
2. B. It starts over and re-ingests every file in the input directory, so the on-call engineer must schedule a deduplication job after every recovery 💬 B
3. C. It skips the partially processed files and leaves a gap that must be backfilled manually before the next run 💬 C
4. D. It truncates the target Delta table and reloads all files so the table returns to a consistent state 💬 D

Reveal answer

Correct answer: It resumes where it left off: files already recorded in checkpoint state are not reprocessed, preserving exactly-once semantics

Reference: https://docs.databricks.com/aws/en/ingestion/cloud-object-storage/auto-loader/