From 445741dbdae5d0f4cfe34956ec296c3178654205 Mon Sep 17 00:00:00 2001 From: CbcWestwolf <1004626265@qq.com> Date: Tue, 26 Nov 2024 16:42:08 +0800 Subject: [PATCH] tidb: add description for var `tidb_ddl_reorg_max_write_speed` (#19445) --- system-variables.md | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/system-variables.md b/system-variables.md index 4f35068052397..b77cae99d1a5a 100644 --- a/system-variables.md +++ b/system-variables.md @@ -1695,6 +1695,17 @@ mysql> SELECT job_info FROM mysql.analyze_jobs ORDER BY end_time DESC LIMIT 1; - This variable is used to set the priority of executing the `ADD INDEX` operation in the `re-organize` phase. - You can set the value of this variable to `PRIORITY_LOW`, `PRIORITY_NORMAL` or `PRIORITY_HIGH`. +### tidb_ddl_reorg_max_write_speed New in v8.5.0 + +- Scope: GLOBAL +- Persists to cluster: Yes +- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No +- Type: Integer +- Default value: `0` +- Range: `[0, 1125899906842624]` (the maximum value that can be set is 1 PiB) +- This variable limits the write bandwidth for each TiKV node and only takes effect when index creation acceleration is enabled (controlled by the [`tidb_ddl_enable_fast_reorg`](#tidb_ddl_enable_fast_reorg-new-in-v630) variable). When the data size in your cluster is quite large (such as billions of rows), limiting the write bandwidth for index creation can effectively reduce the impact on application workloads. +- The default value `0` means no write bandwidth limit. The default unit is bytes per second. You can also set the value in formats such as `'1GiB'` or `'256MiB'`. + ### tidb_ddl_reorg_worker_cnt > **Note:**