عرض عملي: إيجاد span بطيء في ساغا

خطوة بخطوة

1. Start from the symptom: p95 of checkout rose.
2. Pick slow traces; compare with fast ones.
3. Find the widest span: a payment call with retries.
4. Planned mistake: blame the database because "it is usually the database"; the trace shows only 5 ms in SQL. Follow the evidence instead.
5. Confirm with the metric of payment retries and the log lines of the same trace.
6. Write a short diagnosis: symptom, evidence, cause, proposed fix.