pingcap/tidb

enhance `explain analyze` to show more runtime statistics about each operator

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#8,213 建立於 2018年11月7日

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help wantedsig/executiontype/enhancement

描述

With this enhancement, we can identify:

  • the true selectivity for each operator
  • how long it takes to gain the first output record for each operator.

With the help of this kind of information, we can know whether the execution plan is wrong, and how the incorrect or inefficient plan was generated.

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。
3-5 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。
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
GoQuery execution conceptsTiDB architecture
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。
30
研究方向
Examine the current implementation of 'explain analyze' in TiDB's executor package. Review how operators report statistics and identify where to add selectivity and first output time measurements. Look for existing runtime stats structures (e.g., in executor/executor.go) and propose modifications to store and display the new metrics.
enhance `explain analyze` to show more runtime statistics about each operator · pingcap/tidb#8213 | Good First Issue