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# 慢查询管理

IoTDB 会将慢查询输出到单独的日志文件 log_datanode_slow_sql.log 中，并记录其执行耗时。

## 配置慢查询的阈值

IoTDB 在 `iotdb-common.properties` 提供了 `slow_query_threshold` 配置项，单位是毫秒，默认是30秒，超过此参数指定的阈值，便会被判断为慢查询，待其查询执行结束后，将其记录在 log_datanode_slow_sql.log 中。

## 慢查询日志示例

```
2023-07-31 20:15:00,533 [pool-27-IoTDB-ClientRPC-Processor-1$20230731_121500_00003_1] INFO  o.a.i.d.q.p.Coordinator:225 - Cost: 42593 ms, sql is select * from root.db.** 
```