DM MariaDB and FK compatibility clarification by alastori · Pull Request #21769 · pingcap/docs

alastori · 2025-09-11T23:20:33Z

What is changed, added or deleted? (Required)

Updated dm-compatibility-catalog.md to reflect current reality for MariaDB:

Changed MariaDB > 10.5.10 to Not tested with a concise “Should work for most cases (bypass precheck)” remark and pointer to a new subsection.
Added a short, engine-agnostic note that Foreign Keys with CASCADE operations are not supported by DM (DM does not honor cascade effects by default).
Added a MariaDB notes subsection that documents the precheck failure users will see on MariaDB 10.5.11+ due to privilege name changes and how to bypass precheck via task config.
Minor fixes: wording and typos (e.g., “constraints”, “session”).

Rationale: minimize friction for MariaDB users (avoid false “incompatible” impression), set correct expectations on FK/CASCADE semantics, and provide one pointer to the official precheck doc for the required bypass.

Which TiDB version(s) do your changes apply to? (Required)

Tips for choosing the affected version(s):

By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.

For details, see tips for choosing the affected versions.

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

This PR is translated from:
Other reference link(s):
- DM precheck: /dm/dm-precheck.md
- foreign_key_checks variable: /system-variables.md#foreign_key_checks

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

…s, and clarification about current FK support.

gemini-code-assist

Summary of Changes

Hello @alastori, 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 TiDB Data Migration (DM) compatibility catalog documentation to provide more accurate and helpful information for users, particularly those working with MariaDB. The changes aim to clarify DM's behavior regarding MariaDB versions and foreign key cascade operations, offering solutions for common precheck issues and setting correct expectations for data migration.

Highlights

MariaDB Compatibility Update: The compatibility status for MariaDB versions greater than 10.5.10 has been updated from "Incompatible" to "Not tested," with guidance on bypassing prechecks.
Foreign Key CASCADE Clarification: Added a new section clarifying that DM does not honor ON DELETE/UPDATE CASCADE behavior for foreign keys by default.
MariaDB Precheck Guidance: A new subsection "MariaDB notes" has been added to explain precheck failures on MariaDB 10.5.11+ due to privilege name changes and provides instructions on how to bypass these checks.
Documentation Refinements: Minor wording adjustments and typo corrections were made throughout the document for improved clarity.

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gemini-code-assist

Code Review

This pull request effectively clarifies the compatibility of DM with recent MariaDB versions and foreign key cascade operations. The changes are clear and will help users avoid confusion. I've added a few minor suggestions to further improve wording, conciseness, and adherence to the documentation style guide, such as using active voice and ensuring consistent formatting.