pingcap/tidb

support "help" statement

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#16,575 opened on Apr 18, 2020

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feature/acceptedhelp wantedtype/feature-request

Description

Feature Request

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

In some scenarios, people can not access user documents through web browsers to get help.

Describe the feature you'd like:

Support the help statement as MySQL does. See the document for details: 13.8.3 HELP Statement

HELP 'search_string' The HELP statement returns online information from the MySQL Reference Manual. Its proper operation requires that the help tables in the mysql database be initialized with help topic information (see Section 5.1.14, “Server-Side Help Support”).

The HELP statement searches the help tables for the given search string and displays the result of the search. The search string is not case-sensitive.

The search string can contain the wildcard characters % and _. These have the same meaning as for pattern-matching operations performed with the LIKE operator. For example, HELP 'rep%' returns a list of topics that begin with rep.

Describe alternatives you've considered:

Searching from a string maybe is not easy to use. We can combine help command with some sub commands. Such as help error [search_string], help function [search_string], help statements [search_string].

Teachability, Documentation, Adoption, Migration Strategy:

N/A

Contributor guide

Tech stack
gosql
Domain
databasebackend
Issue type
feature
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.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Familiarity with TiDB SQL parserUnderstanding of MySQL HELP system
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
First, review MySQL's HELP statement implementation and MySQL help tables structure. Then, examine TiDB's SQL parser code in the 'parser' directory to see how statements are parsed. Check if there are any existing help related files or comments. Finally, implement a new AST node for HELP, add parsing logic, and create corresponding executor that queries help tables.