pingcap/tidb

Accelerate FindColumn when table has huge number of columns

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#11,151 opened on Jul 9, 2019

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Description

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

Contributor guide

Research direction
Investigate the FindCols and FindColumn functions in the codebase. They use linear search over a slice of columns. Consider replacing linear search with a map from column name to index, or sorting columns and using binary search. Evaluate the trade off between build time and lookup time, especially when the number of columns is large (e.g., >200).
Tech stack
go
Domain
databasebackend
Issue type
Performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
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
Go
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65