Explain 'Stateless' vs 'Stateful' Stream Processing.

Explain 'Stateless' vs 'Stateful' Stream Processing.

Approach: Compare operations that need memory of past events.

Stateless processing treats each record independently (e.g., filtering). Stateful processing requires memory of previous records (e.g., calculating a running sum or joining streams).

Follow-up: Which one is harder to scale?

Key concepts: aggregations, filtering, checkpoints.