br: sys collation check

[Leavrth]

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• This PR is translated from:br: sys collation check docs-cn#21306
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[gemini-code-assist]

Summary of Changes

Hello @Leavrth, 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 TiDB's Backup & Restore (BR) feature. It provides crucial information regarding a new parameter designed to enhance the handling of system table data with differing case-sensitivity and collation settings during the restoration process, particularly for scenarios involving older cluster versions.

Highlights

• New BR Parameter for Collation Check: Introduced documentation for the --sys-check-collation parameter in BR, available from version 8.5.5.
• System Table Case-Sensitivity Handling: This parameter allows BR to check for case-sensitivity conflicts in system table data (e.g., test.t1 and test.T1) during restoration.
• Cross-Collation Compatibility: It enables compatibility checks for data across different collations, facilitating successful restoration of older backups if compatible, or returning an error otherwise.

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[gemini-code-assist]

Code Review

This pull request adds a note about the new --sys-check-collation parameter in BR. My review focuses on improving the clarity, grammar, and style of the new documentation content to align with the repository's style guide. I've suggested a revision to make the text easier to understand and more consistent with the documentation's writing principles, such as using active voice, present tense, and proper formatting for parameters.

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-02-13 01:17:12.586137651 +0000 UTC m=+153985.666128346: ☑️ agreed by hfxsd.

[ti-chi-bot]

@hfxsd: Your lgtm message is repeated, so it is ignored.

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[hfxsd]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hfxsd

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #22462.