比较依赖性 p95 延迟

SELECT
  dependency_name,
  operation,
  COUNT(*) AS calls,
  approx_percentile_cont(latency_ms, 0.50) AS p50_ms,
  approx_percentile_cont(latency_ms, 0.95) AS p95_ms,
  100.0 * SUM(CASE WHEN status <> 'success' THEN 1 ELSE 0 END)
    / NULLIF(COUNT(*), 0) AS failure_rate_pct
FROM dependency_calls
WHERE timestamp_utc >= now() - INTERVAL '24 hours'
GROUP BY dependency_name, operation
HAVING COUNT(*) >= 50
ORDER BY p95_ms DESC
LIMIT 20;