pingcap/tidb

Accelerate FindColumn when table has huge number of columns

Open

#11,151 建立於 2019年7月9日

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 (3 留言) (0 反應) (0 負責人)Go (40,090 star) (6,186 fork)batch import
help wantedtype/enhancementtype/performance

描述

Feature Request

Is your feature request related to a problem? Please describe:

will be frequently called when build query plan or build insert value list.

now it uses linear search to find column info match target name....

when the table has limitation columns it works well...

but when table got many columns (e.g. 200+ columns), upper logic will find 200 columns to do linear search in 200 items.

image

Describe the feature you'd like:

maybe we should adaptively replace a linear search with another method when table has many columns

貢獻者指南

技術棧
go
領域
backenddatabaseperformance
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。
half day
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。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
clear
前置要求
Go programmingTiDB internalsalgorithm optimizationperformance profiling
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。
45
研究方向
The issue points to two functions: FindCols in table/column.go and FindColumn in expression/schema.go. Both currently use linear search to find column info by name. The goal is to replace linear search with a more efficient method (e.g., hash map) when the number of columns is large. Research should start by understanding the current implementation and the data structures used. Then, consider implementing an adaptive approach: keep linear search for small column counts and switch to a map or sorted slice with binary search for larger counts. Profile the performance impact on query planning and insert value building. Check the three comments for any additional insights or suggestions.