測量事件攝取新鮮度

SELECT
  source,
  MAX(timestamp_utc) AS latest_event_at,
  MAX(received_at) AS latest_received_at,
  date_part('second', now() - MAX(received_at)) / 60.0
    AS minutes_since_receive,
  AVG(date_part('second', received_at - timestamp_utc)) / 60.0
    AS average_delivery_delay_minutes
FROM telemetry_events
WHERE received_at >= now() - INTERVAL '24 hours'
  AND environment = 'production'
GROUP BY source
ORDER BY minutes_since_receive DESC;