필수 필드 Null 비율 측정

SELECT
  event_name,
  producer_version,
  COUNT(*) AS events,
  SUM(CASE
    WHEN account_id IS NULL OR trim(account_id) = '' THEN 1
    ELSE 0
  END) AS missing_account_id,
  100.0 * SUM(CASE
    WHEN account_id IS NULL OR trim(account_id) = '' THEN 1
    ELSE 0
  END) / NULLIF(COUNT(*), 0) AS missing_rate_pct
FROM product_events
WHERE timestamp_utc >= now() - INTERVAL '24 hours'
GROUP BY event_name, producer_version
HAVING COUNT(*) >= 20
ORDER BY missing_rate_pct DESC, events DESC;