pingcap/tidb

Non-transactional DML should not use the default scan concurrency

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#67,329 创建于 2026年3月26日

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 (0 评论) (0 反应) (0 负责人)Go (40,090 star) (6,186 fork)batch import
good first issuetype/enhancement

描述

Enhancement

According to https://github.com/pingcap/tidb/blob/fd7c13a9340470233bf0c52c60eb8c04095d394c/pkg/distsql/request_builder.go#L94, when max_distsql_concurrency is the default setting, the first SELECT in non-transactional DML may only use max_distsql_concurrency=2, which affects its performance.

贡献者指南

技术栈
gosql
领域
databaseperformance
议题类型
feature
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
1-2 days
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
fresh
清晰度议题是否清楚说明期望改动、验收标准和下一步。
mostly clear
前置要求
Go programmingTiDB internalsdistsql package
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
50
研究方向
The issue points to `pkg/distsql/request builder.go` line 94 where the default `max distsql concurrency` is used. Investigate why non transactional DML uses this default and how to bypass it to improve performance. Check if a similar pattern exists for transactional queries and whether a different concurrency value should be passed. Review the surrounding code and any related configuration options.