docs: fix sync-diff-inspector limitations in migration tools

[doc-claw-bot]

What is changed, added or deleted? (Required)

This PR updates the sync-diff-inspector row in migration-tools.md on release-8.5 to match the detailed stable documentation.

• Remove the incorrect statement that JSON, BIT, BINARY, and BLOB data are unsupported.
• Clarify that JSON, BLOB/VARBINARY, and BIT are supported.
• Point readers to the detailed restrictions page for FLOAT/DOUBLE and collation-related considerations.

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• master (the latest development version)
• v8.5 (TiDB 8.5 versions)
• v8.4 (TiDB 8.4 versions)
• v8.3 (TiDB 8.3 versions)
• v8.2 (TiDB 8.2 versions)
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• v6.5 (TiDB 6.5 versions)
• v6.1 (TiDB 6.1 versions)
• v5.4 (TiDB 5.4 versions)
• v5.3 (TiDB 5.3 versions)

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

• This PR is translated from:
• Other reference link(s):
  • sync-diff-inspector: clarify data type support and improve collation guidance #22165
  • https://docs.pingcap.com/tidb/stable/sync-diff-inspector/sync-diff-inspector-overview/
  • https://docs.pingcap.com/tidb/stable/migration-tools/

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

Summary by CodeRabbit

• Documentation
  • Updated sync-diff-inspector data type guidance.
  • Clarified support for JSON, BLOB/VARBINARY, and BIT types.
  • Directed users to the restrictions documentation for FLOAT/DOUBLE and collation considerations.

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[coderabbitai]

📝 Walkthrough

Walkthrough

The sync-diff-inspector documentation now lists JSON, BLOB/VARBINARY, and BIT as supported. It also directs readers to the restrictions documentation for FLOAT/DOUBLE and collation considerations.

Changes

Sync-diff-inspector documentation

Layer / File(s)	Summary
Update data-type limitations migration-tools.md	The limitation statement now documents support for JSON, BLOB/VARBINARY, and BIT. It links FLOAT/DOUBLE and collation guidance to the restrictions page.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~2 minutes

Change: Other

Merge Risk: 🔵 Low · up to 4751f

Readers may rely on unsupported BIT widths or mistake JSON false positives for real differences. Clarify the limitations before merging.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the documentation fix for sync-diff-inspector limitations.
Description check	✅ Passed	The description explains the documentation changes, identifies the affected TiDB version, and provides relevant reference links. The omitted optional first-time contributor and AI involvement sections…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

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ℹ️ Review info

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Run ID: 0f92ea01-72db-4677-a80f-dbea32741298

📥 Commits

Reviewing files that changed from the base of the PR and between 6acba5d and 4751f97.

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• migration-tools.md

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[coderabbitai]

🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

🔎 Supported by static analysis

🏁 Script executed:

sed -n '72,95p' migration-tools.md
sed -n '45,70p' sync-diff-inspector/sync-diff-inspector-overview.md
sed -n '310,335p' sync-diff-inspector/sync-diff-inspector-overview.md

Repository: pingcap/docs

Length of output: 7736

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Document the restrictions for JSON and BIT.

The linked restrictions document qualifies the current support claim: JSON string comparisons can produce false positives when collations or character sets differ, and BIT is validated only for MySQL-to-TiDB comparisons with widths 1, 8, 16, and 64. The current summary does not expose these limits.

Suggested replacement

Suggested change

- Data type support varies by type. JSON, BLOB/VARBINARY, and BIT are supported. For FLOAT/DOUBLE and collation-related considerations, see [Restrictions of sync-diff-inspector](/sync-diff-inspector/sync-diff-inspector-overview.md).

- Data type support varies by type. JSON is supported, but collation and character set differences for JSON string values can cause false positives. BLOB/VARBINARY are supported and compared byte-for-byte. BIT is supported for MySQL to TiDB comparisons for widths 1, 8, 16, and 64. For FLOAT/DOUBLE and additional collation considerations, see [Restrictions of sync-diff-inspector](/sync-diff-inspector/sync-diff-inspector-overview.md).