tidb: add GB18030 doc

[hfxsd]

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• This PR is translated from:tidb: add GB18030 doc docs-cn#18662
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[gemini-code-assist]

Summary of Changes

Hello @hfxsd, 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 significantly enhances the documentation around character set support in TiDB by introducing comprehensive details for the GB18030 character set. It provides a new dedicated guide for GB18030, integrates its information into existing character set and collation overviews, and clarifies compatibility considerations for various TiDB tools and components. The changes aim to provide users with a clearer understanding of GB18030's behavior and limitations within the TiDB ecosystem.

Highlights

• GB18030 Character Set Documentation: Introduced a new dedicated document (character-set-gb18030.md) detailing TiDB's support for the GB18030-2022 character set, including its compatibility with MySQL and various TiDB components.
• Updated Character Set Overviews: Modified character-set-and-collation.md to include GB18030 in the list of supported character sets and collations, and updated information-schema-character-sets.md and migrate-from-mariadb.md with GB18030 details.
• Compatibility Clarifications: Added specific compatibility notes for GB18030 in backup/restore (br/backup-and-restore-overview.md), data migration (dm/dm-overview.md), and general MySQL compatibility (mysql-compatibility.md).
• GBK Documentation Refinement: Updated character-set-gbk.md to clarify the default collation behavior and examples when the new collation framework is enabled.

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[gemini-code-assist]

Code Review

This pull request adds documentation for the GB18030 character set. The changes are mostly good, but I've provided several suggestions to improve clarity, consistency, and correctness across the new and updated documentation files. Key suggestions include making summaries more concise, fixing typos, clarifying misleading descriptions, and restructuring a confusing section in one of the documents.

[ti-chi-bot]

@Frank945946: adding LGTM is restricted to approvers and reviewers in OWNERS files.

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[fzzf678]

Rest LGTM

[fzzf678]

This should be removed according https://github.com/pingcap/docs-cn/pull/18662/files#diff-d814c7fc5fe39bf56a3839975e44bdeba3e92e16e8f6a01afa5c1cc7f685def1L27-L29, or remove the Chinese version modification, anyway, they should be unified

[ti-chi-bot]

@fzzf678: adding LGTM is restricted to approvers and reviewers in OWNERS files.

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Rest LGTM

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[lilin90]

/lgtm

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-11-18 07:56:52.993782766 +0000 UTC m=+1380062.436812635: ☑️ agreed by lilin90.

[hfxsd]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hfxsd

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[lilin90]

/hold

[lilin90]

/unhold