What characterizes automatic watermarks?

• A. Automatic watermarks are handled manually by a developer
• B. Automatic watermarks require explicit saving, retrieving, and comparing
• C. Automatic watermarks are defined per manual process
• D. Automatic watermarks saved, retrieved, and compared automatically through an object store

Answer: (D)

Automatic watermarks are markers that the runtime manages to track how far processing has advanced, using a shared store to persist this progress. In this approach, the system automatically saves the watermark value, retrieves it when needed (such as after a restart or across multiple nodes), and compares it with new data to decide what to process next. This eliminates the need for manual persistence or comparison logic—the object store handles all of that behind the scenes, coordinating across instances and ensuring consistent progress.

This is why the option describing automatic saving, retrieval, and comparison through an object store fits best. The other descriptions imply developers must manually handle persistence or define the process themselves, which is not how automatic watermarks operate.