stream-processing

name	stream-processing
description	Process streams correctly: aggregate on event-time with watermarks (not processing-time), window deliberately (tumbling/sliding/session), handle late data explicitly, checkpoint and TTL-bound state, join with aligned time, and design for backpressure.

Stream Processing

Event-time + watermarks

Aggregate on the event's timestamp; a watermark closes windows correctly. Processing-time breaks on late/out-of-order events.

Windows

Tumbling (fixed) / sliding (overlapping) / session (activity gap) — the window IS the question.

Late data

Allowed lateness + side output, or accept the drop — never silently lose late events.

State & backpressure

Checkpoint stateful operators; TTL-bound state (unbounded = OOM). Joins align event-time + hold state. Handle backpressure; monitor consumer lag -> observability-sre.