# Sql Query Time-Out Case Study Summary


![left](./student-guide/diagram/03-15-1.png)

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- There is latency jitter on multiple TiDB instance on the monitor, indicating that the problem is not from the TiDB server itself or changes in business traffic (QPS is relatively stable on monitoring), and may be affected by TiKV or PD

- PD Client confirms that there are no exceptions in the TSO request

- KV Errors has no exception backoff retries, and KV Request clearly sees latency jitter in store-25935. The request type is BatchGet, which matches the characteristics of the check.

- In summary, we have located that the query time-out source is the delay jitter of store-25935, and the reason for the store jitter of TiKV needs to be further analyzed

```
Grafana TiDB --> Query Summary --> Duration
Grafana TiDB --> Query Summary --> QPS
Grafana TiDB --> Query Summary - 999/99/95/80 Duration
Grafana TiDB --> Query Detail - Duration 999/99/95/80 by Instance
Grafana TiDB --> PD Client - PD TSO Wait/RPC Duration
Grafana TiDB --> KV Errors - KV Backoff Duration/OPS
Grafana TiDB --> KV Request - KV Request Duration 99 by store/type
Grafana TiDB --> Executor - Parse/Compile Duration
```