DM: Get DB flavor from source instead of guessing it

[dveeden]

What problem does this PR solve?

Issue Number: close #12423

What is changed and how it works?

Check List

Tests

• Manual test (add detailed scripts or steps below)

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

The source database flavor detection has been improved to better handle MariaDB

[gemini-code-assist]

Summary of Changes

Hello @dveeden, 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 addresses an issue where the system was incorrectly guessing the database flavor, leading to potential problems with Global Transaction Identifier (GTID) parsing, especially for MariaDB. By explicitly connecting to the source database to determine its flavor, the changes ensure that GTIDs are parsed accurately, improving the robustness and compatibility of data migration processes.

Highlights

• Improved Database Flavor Detection: The system now actively queries the upstream database to determine its specific flavor (e.g., MySQL, MariaDB) instead of relying on assumptions.
• Enhanced GTID Parsing: The detected database flavor is now passed to the GTID parser, allowing for more accurate parsing of Global Transaction Identifiers, particularly beneficial for MariaDB's GTID format.
• Refactored Metadata Parsing: The dumpling.ParseMetaData and dumpling.ParseMetaDataByReader functions have been updated to accept the database flavor, ensuring that metadata files are interpreted correctly based on the source database type.

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[dveeden]

/check-issue-triage-complete

[dveeden]

/cc @lance6716 @GMHDBJD

[gemini-code-assist]

Code Review

This pull request aims to improve database flavor detection by actively querying the source database instead of guessing. This is a good improvement for robustness, especially for MariaDB.

However, I've found a couple of critical issues where the new logic could cause a panic due to a nil pointer dereference when a database connection cannot be established. I've provided suggestions to fix these.

Additionally, some code duplication has been introduced. My review includes suggestions to address this for better code quality and maintainability.

[dveeden]

/retest

[dveeden]

/cc @OliverS929

[lance6716]

Please run a manual test after last commit to double check it can work

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-11-30 11:28:56.68738255 +0000 UTC m=+176481.501160122: ☑️ agreed by lance6716.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lance6716

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• dm/OWNERS [lance6716]

Approvers can indicate their approval by writing /approve in a comment
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[dveeden]

Please run a manual test after last commit to double check it can work

Yes, I did.