Update for DM related docs

[dveeden]

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What is changed, added or deleted? (Required)

• Weaken the stance that we don't support foreign keys
• Mention binlog transaction compression in a few more places

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[gemini-code-assist]

Summary of Changes

Hello, 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 refines the Data Migration (DM) documentation by updating details on foreign key compatibility and integrating explicit requirements for MySQL's binlog_transaction_compression setting. These changes aim to enhance the accuracy and completeness of the documentation, guiding users more effectively through the DM configuration process.

Highlights

• Foreign Key Documentation Clarification: The documentation's stance on foreign key support in TiDB DM has been softened from 'not supported' to 'not fully supported', providing a more accurate description of compatibility.
• Binlog Transaction Compression Requirement: Explicit requirements for binlog_transaction_compression=OFF have been added to the DM documentation, including precheck items and configuration examples, to ensure compatibility during data migration.

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Changelog

• dm/dm-compatibility-catalog.md
  • Updated table formatting for data sources.
• dm/dm-precheck.md
  • Clarified foreign key support from "not supported" to "not fully supported" in precheck descriptions.
  • Added a precheck item for binlog_transaction_compression=OFF.
  • Adjusted table formatting for precheck items.
• tidb-cloud/migrate-from-mysql-using-data-migration.md
  • Updated table formatting for data sources.
  • Added binlog_transaction_compression = OFF as a required binary log configuration.
  • Included binlog_transaction_compression in the SHOW VARIABLES command example.
  • Added binlog_transaction_compression = OFF to the example MySQL configuration.

Activity

• No additional activity (comments, reviews, or progress updates) has been recorded on this pull request since its creation.

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[gemini-code-assist]

Code Review

This pull request updates documentation related to TiDB Data Migration (DM), primarily to clarify foreign key support and add information about binlog transaction compression. The changes correctly reflect that foreign keys are 'not fully supported' rather than 'not supported', and consistently add the binlog_transaction_compression=OFF requirement across relevant documents. The changes are well-aligned with the stated goals. I have one minor suggestion for stylistic consistency.

_{Note: Security Review has been skipped due to the limited scope of the PR.}

[alastori]

Thanks for the binlog transaction compression additions — those are solid and well-placed across precheck + Cloud migration guide.

Two suggestions on the FK wording and a consistency nit. Context: TiDB fully supports foreign keys (GA since v8.5.0). The limitation is DM's replication behavior, not TiDB's FK support. There's an open issue tiflow#12129 specifically about the misleading DM warning message, and active engineering work on DM FK support this week (tiflow#12552, tiflow#12541, tiflow#12414). The compatibility catalog already correctly frames this as a DM limitation, not a TiDB limitation.

[dveeden]

/retest

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-04-15 02:27:55.447161345 +0000 UTC m=+1528080.652521412: ☑️ agreed by qiancai.

[hfxsd]

/approve

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #22757.