pingcap/tidb

push avg & distinct functions across join when tidb_opt_agg_push_down is set

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#16,355 建立於 2020年4月14日

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feature/acceptedhelp wantedsig/plannertype/feature-request

描述

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

When tidb_opt_agg_push_down is on, currently it does not support pushing avg function and distinct functions across Join.

After https://github.com/pingcap/tidb/pull/16344, it supports pushing those across Union, we should make it happen w/ Join, too.

2. What did you expect to see?

3. What did you see instead?

4. What version of TiDB are you using? (tidb-server -V or run select tidb_version(); on TiDB)

e90aac271

貢獻者指南

技術棧
go
領域
databaseperformance
議題類型
bug
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。
4
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
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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
GoTiDB query optimizeraggregate push down concepts
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。
25
研究方向
Study the referenced PR #16344 to understand how aggregate push down was implemented for Union. Then examine the join push down logic in the TiDB optimizer, focusing on files like `planner/core/rule aggregation push down.go`. The goal is to extend support for avg and distinct functions across Join when `tidb opt agg push down` is enabled.
push avg & distinct functions across join when tidb_opt_agg_push_down is set · pingcap/tidb#16355 | Good First Issue