How do you ensure accurate counts with duplicate analytics events?
Tests your grasp of data integrity under at-least-once delivery. Explain why COUNT(*) is inflated, then propose deduplication using a unique event ID. Mention trade-offs of stateful processing. A red flag is ignoring the cost or the need for a unique ID.
This tests your understanding of data integrity under at-least-once delivery. A great answer first explains that COUNT(*) overcounts logins due to duplicates. Then, it proposes adding a unique event_id at creation and using COUNT(DISTINCT event_id) for accurate reporting. Discussing the performance trade-offs of this versus stateful stream processing demonstrates seniority. A red flag is suggesting COUNT(DISTINCT user_id), which answers a different question, or ignoring the cost of deduplication.
Read the original → cloud.google.com
- #data pipelines
- #analytics
- #system design
- #sql
- #idempotency
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