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tidb: enable global memory arbitration in priority mode by default #21827

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tidb: enable global memory arbitration in priority mode by default #21827

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Update system-variables.md
solotzg Jul 22, 2026
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solotzg Jul 22, 2026
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Update system-variables.md with memory management details
solotzg Jul 22, 2026
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4 changes: 2 additions & 2 deletions system-variables.md
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Expand Up @@ -3506,10 +3506,10 @@ v5.0 后，用户仍可以单独修改以上系统变量（会有废弃警告）
- 是否持久化到集群：是
- 是否受 Hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value) 控制：否
- 类型：枚举型
- 默认值：`disable`
- 默认值：`priority`

@qiancai qiancai Jul 25, 2026

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改了默认值后，相当于这个功能在所有环境都默认开启了，那前面的 “该变量控制的功能为实验特性，不建议在生产环境中使用” 还需要保留吗，有些矛盾

- 可选值：`disable`、`standard`、`priority`
- 该变量用于设置 TiDB 实例的内存管理模式，详见 [TiDB 内存控制](/configure-memory-usage.md#内存仲裁模式)。有以下取值：
- `disable`（默认值）：表示禁用内存仲裁模式，保持内存资源[先使用后上报](/system-variables.md#tidb_server_memory_limit-从-v640-版本开始引入)的机制。
- `disable`：表示禁用内存仲裁模式，保持内存资源[先使用后上报](/system-variables.md#tidb_server_memory_limit-从-v640-版本开始引入)的机制。
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- `standard`：表示启用标准内存仲裁模式。SQL 需要使用内存资源时，先向内存仲裁者进行订阅，订阅成功后再分配内存资源。如果订阅失败，SQL 终止执行。
- `priority`：表示启用基于优先级的内存仲裁模式。SQL 需要使用内存资源时，先向内存仲裁者进行订阅，订阅成功后再分配内存资源。TiDB 根据 SQL 的[资源组优先级](/information-schema/information-schema-resource-groups.md)处理内存资源订阅请求。

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