pingcap/tidb

Investigate and propose Adaptive Join

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#14,408 opened on Jan 9, 2020

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help wantedsig/executionsig/plannertype/enhancement

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Description

Feature Request

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

Sometimes optimizer need defer the choise of Hash Join or Index Nested loops Join because it does not have a deterministic statistics.

Describe the feature you'd like:

We need someone who is familiar with planner and executor to drive and propose a plan, and see how we can be benefited with Adaptive Join.

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

Contributor guide

Research direction
Research adaptive join implementations in SQL databases (e.g., SQL Server, Oracle) and propose a plan for TiDB. Focus on planner and executor changes.
Tech stack
go
Domain
database
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GoDatabase internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20