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| # 性能追踪工具 |
| |
| > 注意：0.13及以上版本中将不再支持0.12中的 `TRACING ON/OFF` 。 |
| |
| IoTDB 支持使用 `TRACING` 关键词对查询语句进行性能追踪。用户可以分析查询语句执行中存在的潜在性能问题。 |
| |
| 性能追踪的结果包括： |
| 1. 执行过程中各个阶段的累积耗时。 |
| 2. 与性能分析相关的统计信息。对于查询语句，包括查询的时间序列数、涉及访问的 Tsfile 文件数、需要扫描的 chunk 总数以及平均每个 chunk 包含的数据点个数、读取的 Page 总数以及其中乱序 Page 的个数。 |
| |
| **示例：** |
| |
| 例如执行 `tracing select * from root.**`，输出结果如下： |
| |
| ``` |
| Tracing Activties: |
| +---------------------------------------------------------+------------+ |
| | Activity|Elapsed Time| |
| +---------------------------------------------------------+------------+ |
| |Start to execute statement: tracing select * from root.**| 0| |
| | Parse SQL to physical plan| 4| |
| | Create and cache dataset| 16| |
| | * Num of series paths: 3| | |
| | * Num of sequence files read: 2| | |
| | * Num of unsequence files read: 1| | |
| | * Num of sequence chunks: 6, avg points: 100.0| | |
| | * Num of unsequence chunks: 3, avg points: 100.0| | |
| | * Num of Pages: 9, overlapped pages: 0 (0.0%)| | |
| | Request complete| 20| |
| +---------------------------------------------------------+------------+ |
| ``` |
