schema_version: 1
id: intermittent-plan-regression-during-cpu-spike
title: Intermittent plan regression during CPU spike
status: draft
owner: codex
source: jira
environment:
  profile: stable-dedicated
  cluster_id: '1379661944636084123'
  cluster_type: dedicated
  tidb_version: v6.5.6
time_window:
  incident_at: '2026-06-04T13:00:00Z'
  allowed:
  - id: reported_incident_window
    start: '2026-06-04T12:30:00Z'
    end: '2026-06-04T13:30:00Z'
prompt:
  text: 请分析集群 1379661944636084123 在 2026-06-04T12:30:00Z 到 2026-06-04T13:30:00Z 的 SQL 延迟和 TiKV CPU 异常。同一条包含多表外连接的查询会随 ref_id 参数取值偶发选择明显更慢的执行计划，并把 TiKV CPU 拉高。请解释为什么计划会变化，判断根因并给出稳定计划的建议。
tags:
- sql
- latency
- cpu
case_tier: P0
cost_tier: medium
followup:
  scheduled_max_followups: 0
execution:
  acp_bash_timeout_s: 900