Update system-variables tidb_ddl_reorg_batch_size and tidb_ddl_reorg_…

[Frank945946]

…worker_cnt

First-time contributors' checklist

• I've signed the Contributor License Agreement, which is required for the repository owners to accept my contribution.

Update system-variables tidb_ddl_reorg_batch_size and tidb_ddl_reorg_worker_cnt

Which TiDB version(s) do your changes apply to? (Required)

Tips for choosing the affected version(s):

By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions.

• master (the latest development version)
• v9.0 (TiDB 9.0 versions)
• v8.5 (TiDB 8.5 versions)
• v8.1 (TiDB 8.1 versions)
• v7.5 (TiDB 7.5 versions)
• v7.1 (TiDB 7.1 versions)
• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)

What is the related PR or file link(s)?

• This PR is translated from:Update system-variables tidb_ddl_reorg_batch_size and tidb_ddl_reorg_… docs-cn#20941
• Other reference link(s):

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

[gemini-code-assist]

Summary of Changes

Hello @Frank945946, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the documentation for two critical system variables, tidb_ddl_reorg_batch_size and tidb_ddl_reorg_worker_cnt. The updates clarify that these parameters can now be dynamically adjusted during DDL operations using the ADMIN ALTER DDL JOBS command, a feature introduced in TiDB version 8.5.0. This change provides users with greater control and flexibility over DDL execution without requiring session restarts.

Highlights

• Documentation Update for tidb_ddl_reorg_batch_size: The documentation for tidb_ddl_reorg_batch_size has been updated to reflect that it can be modified using the ADMIN ALTER DDL JOBS command starting from TiDB v8.5.0.
• Documentation Update for tidb_ddl_reorg_worker_cnt: The documentation for tidb_ddl_reorg_worker_cnt has been updated to reflect that it can be modified using the ADMIN ALTER DDL JOBS command starting from TiDB v8.5.0.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request updates the documentation for the tidb_ddl_reorg_batch_size and tidb_ddl_reorg_worker_cnt system variables to include information about modifying them for running DDL jobs. The changes are accurate, but I've suggested some minor improvements for clarity and to align with the style guide, such as using backticks for code and commands and adopting the second-person point of view.

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-09-22 14:04:40.463331714 +0000 UTC m=+279090.533825418: ☑️ agreed by tangenta.
• 2025-09-24 06:44:08.752671543 +0000 UTC m=+425458.823165254: ☑️ agreed by hfxsd.

[hfxsd]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hfxsd

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [hfxsd]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #21829.