tidb: add the refresh stats statement

[0xPoe]

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What is changed, added or deleted? (Required)

ref pingcap/tidb#61273

Added the documentation for the refresh stats statement.

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

• This PR is translated from:
• Other reference link(s): Tracking issue: Refresh Stats Command tidb#61273

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[gemini-code-assist]

Summary of Changes

Hello @0xPoe, 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 focuses on documenting the REFRESH STATS SQL statement for TiDB. This new documentation provides users with detailed information on how to reload optimizer statistics into memory, which is essential for maintaining optimal query performance, especially after data restorations or when manual reconciliation of in-memory statistics is required. The changes include adding the statement to relevant navigation and overview pages, alongside a dedicated, in-depth guide covering its syntax, options, and practical examples.

Highlights

• New SQL Statement Documentation: This pull request introduces comprehensive documentation for the REFRESH STATS SQL statement, detailing its purpose, syntax, options, and usage examples within TiDB.
• Table of Contents Integration: The REFRESH STATS statement has been added to the main Table of Contents (TOC.md) under the SQL statements section, ensuring discoverability for users.
• SQL Statement Overview Update: An entry for REFRESH STATS has been included in the sql-statement-overview.md, providing a brief description of its function: "Reloads persisted statistics into memory for specific tables or the entire cluster."
• Statistics Documentation Enhancement: The statistics.md file has been updated with a new section explaining how to refresh in-memory statistics using the REFRESH STATS statement, including details on targeting and initialization modes.

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[gemini-code-assist]

Code Review

This pull request adds documentation for the new REFRESH STATS statement. The changes include adding the new statement to the table of contents and SQL overview, creating a new page for REFRESH STATS, and updating the statistics documentation. The new documentation is well-written and comprehensive. I've provided a couple of minor suggestions to improve wording and consistency with the style guide. Overall, great work!

[gemini-code-assist]

Summary of Changes

Hello @0xPoe, 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 focuses on enhancing the TiDB documentation by adding a dedicated page for the REFRESH STATS SQL statement. This new statement allows users to explicitly reload persisted optimizer statistics into memory, which is particularly useful after external statistics restoration or when in-memory statistics need to be synchronized without a full ANALYZE operation. The changes ensure that users have clear guidance on how to manage and refresh statistics effectively within TiDB.

Highlights

• New Documentation for REFRESH STATS: This pull request introduces comprehensive documentation for the REFRESH STATS SQL statement, detailing its purpose, syntax, and usage.
• Integration into Documentation Structure: The new REFRESH STATS documentation has been integrated into the main Table of Contents (TOC.md) and the SQL statement overview (sql-statement-overview.md), ensuring discoverability.
• Detailed Usage and Options: The documentation provides in-depth explanations of REFRESH STATS options, including target specification (individual tables, databases, or cluster-wide), refresh modes (FULL/LITE), and the CLUSTER keyword for broadcasting requests across TiDB nodes.

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
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
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[gemini-code-assist]

Code Review

This pull request adds documentation for the new REFRESH STATS SQL statement. The changes are well-structured and introduce the new feature clearly by adding it to the table of contents, the SQL statements overview, and its own dedicated page. A brief mention is also added to the main statistics documentation. The new content is comprehensive and follows the documentation style guide. I have a few minor suggestions to enhance consistency and readability, which are detailed in the comments.

[0xPoe]

I think this is a false positive feedback: https://github.com/pingcap/docs/actions/runs/18338863546/job/52229172406?pr=21873

[time-and-fate]

Others LGTM.

[time-and-fate]

If I understand it correctly, the user doesn't need to run this statement even in the BR workflow.
I think the current wording may lead readers to mistakenly think that they need to run this statement if they are using BR. I think it's better to explicitly say that it's used by BR internally.

[ti-chi-bot]

@time-and-fate: adding LGTM is restricted to approvers and reviewers in OWNERS files.

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Others LGTM.

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