Top 4 Event time Interview Questions
Browse 4 real-world technical and behavioral interview questions about Event time. Review scenarios, edge cases, and architectural best practices.
Events for a daily revenue table arrive up to three days late. How do you design the pipeline and the backfill?
Land raw events unchanged by arrival date, then rebuild each revenue day from that raw layer by event date. Each run overwrites only the days its new arrivals touched, a day is provisional until the three-day window closes, and the backfill is the same job run over a date range, never a separate script.
How would you design a data pipeline you can safely re-run?
Design a safely rerunnable data pipeline by making each output partition a deterministic result of its input partition, overwriting instead of appending, and writing into idempotent sinks that tolerate retries and late events.
Usage records arrive duplicated, late and out of order, and the tariff changed in the middle of the month. How does mediation and rating cope?
Mediation normalises and deduplicates records against a persisted key window sized to the worst observed lateness, then rating prices each record by its event time against an effective-dated tariff version. Prepaid is not merely faster postpaid; it reserves quota against a live balance.
An event for 23:58 yesterday arrives at 00:20 today, after you have already published yesterday's totals. What should your pipeline do?
Decide it deliberately, because there is no correct default: you can hold the window open longer, accept the record and restate the figure, or drop it and report how much you dropped. What you must not do is let arrival order silently decide, which is what a pipeline keyed on ingestion time does.