How do duplicate events bias COUNT(*) and daily login reports?
Tests idempotency in streaming analytics. COUNT(*) overcounts; fix with unique event ID dedup via idempotent writes or COUNT(DISTINCT id), plus daily partition reconciliation. Red flag: SELECT DISTINCT * without a stable key or no reporting safeguard.
WHAT IT TESTS: This evaluates your understanding of exactly-once semantics and idempotent aggregations in streaming pipelines. ANSWER OUTLINE: COUNT(*) overcounts because duplicates inflate totals; propose deduplication via a unique event ID using idempotent writes or COUNT(DISTINCT event_id), plus daily partition reconciliation and watermarking for deterministic reruns. RED FLAG: Recommending SELECT DISTINCT * without a stable unique key, or assuming upstream pipeline fixes alone remove the need for defensive reporting logic.
Read the original → cloud.google.com
- #analytics
- #streaming
- #idempotency
- #data-warehousing
- #deduplication
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