Question

A retail analytics team runs a Dataflow streaming pipeline that reads clickstream events from Pub/Sub and aggregates purchase counts into 1-hour fixed windows. Business users complain that they must wait up to an hour to see any partial results on the live dashboard. The team wants to emit approximate running totals every minute while the window is still open, then emit a final corrected result when the window closes and watermark passes. Which Apache Beam configuration best achieves this?

Accepted Answer

Apply a fixed window of 1 hour with an early trigger firing at 1-minute processing-time intervals plus an on-time trigger at the watermark, using accumulating mode.

Answer

Reduce the fixed window size to 1 minute so results are emitted every minute, then re-aggregate downstream into hourly totals in BigQuery.

Answer

Use a global window with a processing-time trigger firing every minute in discarding mode, and rely on allowed lateness to correct results.

Answer

Apply a session window with a 1-minute gap duration so partial results are emitted whenever activity pauses for a minute.