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sys var: clarify the description of tidb_ddl_reorg_max_write_speed (#20042) #20053

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ti-chi-bot merged 4 commits into from
Mar 17, 2025
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sys var: clarify the description of tidb_ddl_reorg_max_write_speed (#20042) #20053

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This is an automated cherry-pick of #20042
CbcWestwolf Mar 17, 2025
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Update system-variables.md
hfxsd Mar 17, 2025
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hfxsd Mar 17, 2025
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hfxsd Mar 17, 2025
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9 changes: 6 additions & 3 deletions system-variables.md
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Expand Up @@ -1011,11 +1011,14 @@ MPP 是 TiFlash 引擎提供的分布式计算框架，允许节点之间的数

- 作用域：GLOBAL
- 是否持久化到集群：是
- 类型：整数型
- 类型：字符串
- 默认值：`0`
- 范围：`[0, 1125899906842624]`（即最大可设置为 1 PiB）
- 范围：`[0, 1PiB]`
- 这个变量用于限制每个 TiKV 节点写入的带宽，仅在开启添加索引加速功能时生效（由变量 [`tidb_ddl_enable_fast_reorg`](#tidb_ddl_enable_fast_reorg-从-v630-版本开始引入) 控制）。在数据量特别大的情况下（如数十亿行数据），降低加索引时写入 TiKV 节点的带宽可以有效减少对业务负载的影响。
- 默认值 `0` 表示不限制写入带宽。默认单位为字节每秒，也可以通过 `'1GiB'`、`'256MiB'` 等格式设置该变量。
- 默认值 `0` 表示不限制写入带宽。
- 该变量可设置为带单位的格式或不带单位的格式。
- 当该变量值不带单位时，默认单位为字节每秒。例如 `67108864` 表示 `64MiB` 每秒。
- 当该变量值带单位时，支持的单位包括 KiB、MiB、GiB、TiB。例如，`'1GiB'` 表示 1 GiB 每秒， `'256MiB'` 表示 256 MiB 每秒。

### `tidb_ddl_reorg_worker_cnt`

Expand Down