pingcap/tidb

Non-transactional DML should not use the default scan concurrency

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#67,329 建立於 2026年3月26日

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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.

貢獻者指南

技術棧
gosql
領域
databaseperformance
議題類型
feature
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
1-2 days
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
fresh
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
mostly clear
前置要求
Go programmingTiDB internalsdistsql package
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
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.