dm: fix validator handling for unsigned columns

[OliverS929]

What problem does this PR solve?

Issue Number: close #12178

What is changed and how it works?

DM validator now normalizes row images with adjustValueFromBinlogData before building RowChange, so UNSIGNED values follow the same conversion path as syncer.
This prevents high-bit UNSIGNED values from being treated as negative signed integers during row key generation and downstream validation.
A regression test is added for an int unsigned primary key case.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Questions

Will it cause performance regression or break compatibility?

No. This only reuses the existing binlog value normalization path in validator.

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

No.

Release note

Fixed false-positive DM validator errors on UNSIGNED columns by normalizing row values before validation.

[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 resolves a critical data validation issue within the DM validator where UNSIGNED integer values were being misinterpreted, causing erroneous validation failures. By integrating a consistent value normalization process, the system now correctly handles these data types, preventing false positives and ensuring data integrity during replication and validation.

Highlights

• Data Validation Fix: The DM validator now normalizes row images using adjustValueFromBinlogData before constructing RowChange objects. This ensures that UNSIGNED values are processed consistently, mirroring the syncer's conversion path.
• Prevention of Negative Integer Misinterpretation: This change specifically addresses an issue where high-bit UNSIGNED values were incorrectly treated as negative signed integers during row key generation and subsequent validation, leading to false positives.
• New Regression Test: A new regression test has been added to cover the scenario of an int unsigned primary key, ensuring the fix correctly handles such cases.

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Changelog

• dm/syncer/data_validator.go
  • Fixed false-positive DM validator errors on UNSIGNED columns by normalizing row values before validation.

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[gemini-code-assist]

Code Review

This pull request addresses an issue with the DM validator's handling of unsigned columns, which was causing false-positive errors. The fix involves normalizing row images using adjustValueFromBinlogData before validation, which aligns the validator's behavior with the syncer's. A regression test for an int unsigned primary key has been added to verify the fix.

The changes are logical and the new test case effectively validates the correction. I have one minor suggestion regarding a helper function to improve code clarity. Overall, this is a solid contribution.

[gemini-code-assist]

Code Review

This pull request correctly addresses an issue with UNSIGNED column handling in the DM validator by normalizing row values before validation, aligning it with the syncer's behavior. The addition of a regression test for an int unsigned primary key is a valuable addition. I have one suggestion to simplify the implementation by inlining a new helper function, which would slightly improve code clarity.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: GMHDBJD, kennytm

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Details

Needs approval from an approver in each of these files:

• dm/OWNERS [GMHDBJD]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-03-13 05:06:59.825463801 +0000 UTC m=+585851.337521472: ☑️ agreed by kennytm.
• 2026-03-13 05:40:58.487737939 +0000 UTC m=+587889.999795610: ☑️ agreed by GMHDBJD.

[OliverS929]

/cherry-pick release-8.5

[ti-chi-bot]

@OliverS929: new pull request created to branch release-8.5: #12555.

Details

In response to this:

/cherry-pick release-8.5

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #12557.