Update system-variables tidb_ddl_reorg_batch_size and tidb_ddl_reorg_… (#21819)

[ti-chi-bot]

This is an automated cherry-pick of #21819

…worker_cnt

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Update system-variables tidb_ddl_reorg_batch_size and tidb_ddl_reorg_worker_cnt

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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 @ti-chi-bot, 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 updates the documentation for two critical system variables, tidb_ddl_reorg_batch_size and tidb_ddl_reorg_worker_cnt. The primary purpose of these updates is to inform users about the newly introduced capability in TiDB v8.5.0 to dynamically alter these parameters for DDL jobs that are already in progress. This enhancement provides database administrators with more flexibility to manage and optimize the performance of DDL operations without needing to restart or cancel ongoing tasks.

Highlights

• Dynamic DDL Reorganization Batch Size: Documentation has been updated to reflect that, starting from TiDB v8.5.0, the tidb_ddl_reorg_batch_size system variable can be dynamically modified for a running DDL job using the ADMIN ALTER DDL JOBS command. This provides greater control over DDL performance during execution.
• Dynamic DDL Reorganization Worker Count: The documentation for tidb_ddl_reorg_worker_cnt has been updated to indicate that, as of TiDB v8.5.0, this parameter can also be adjusted for active DDL jobs via the ADMIN ALTER DDL JOBS command, allowing for on-the-fly tuning of DDL concurrency.

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[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. The changes add information about the new capability in v8.5.0 to modify these parameters for running DDL jobs using the ADMIN ALTER DDL JOBS statement. My review provides minor suggestions to improve the clarity and conciseness of the new content, aligning with the style guide's principle of avoiding unnecessary words.

[hfxsd]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hfxsd

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