sink(ticdc): retry later when meet unexpected DDL state

[wk989898]

What problem does this PR solve?

Issue Number: close #12482

What is changed and how it works?

When meeting the unexpected DDL state, instead of immediately failing, CDC now attempts to retry the DDL. This change aims to avoid CDC restart.

Check List

Tests

• Unit test
• Integration test

Questions

Will it cause performance regression or break compatibility?

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

Release note

Avoid CDC restart when meeting lots of slow DDL.

[gemini-code-assist]

Summary of Changes

Hello @wk989898, 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 enhances the robustness of the TiCDC DDL sink by modifying its error handling for unexpected DDL states. Instead of immediately failing, the system will now attempt to retry the operation, treating such states as transient issues. This change aims to prevent potential data inconsistencies or interruptions in DDL replication.

Highlights

• DDL State Handling: Modified the DDL sink to retry operations when an unexpected DDL state is encountered, preventing immediate failure and improving robustness.
• Error Wrapping: Wrapped the ErrDDLStateNotFound with mysql.ErrInvalidConn to signal that this condition should trigger a retry mechanism in the DDL sink.

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[gemini-code-assist]

Code Review

This pull request modifies the DDL sink logic to retry when an unexpected DDL state is encountered. Specifically, when a DDL job is not found in the downstream TiDB after a connection error, instead of failing immediately, it now triggers a retry of the DDL execution. This is achieved by wrapping the ErrDDLStateNotFound with mysql.ErrInvalidConn to make it retryable. While this works, I've suggested a cleaner implementation for better long-term maintainability by making ErrDDLStateNotFound inherently retryable, which would make the code's intent clearer.

[gemini-code-assist]

While wrapping the error with mysql.ErrInvalidConn does make it retryable by the outer retry.Do loop, this approach is a bit misleading as the underlying issue is not a connection error. This could make debugging more difficult in the future.

A cleaner approach would be to make errors.ErrDDLStateNotFound itself retryable. This could be achieved by modifying errorutil.IsRetryableDDLError to recognize errors.ErrDDLStateNotFound.

For example, in pkg/errorutil/util.go:

func IsRetryableDDLError(err error) bool {
	if errors.Is(err, cerror.ErrDDLStateNotFound) {
		return true
	}
	// ... existing code
}

This would make the intent clearer and avoid misrepresenting the error. If changing errorutil is out of scope for this PR, the current change is acceptable as a workaround, but consider refactoring this in the future.

[wk989898]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: asddongmen, hongyunyan

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

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Details

Needs approval from an approver in each of these files:

• OWNERS [asddongmen,hongyunyan]

Approvers can indicate their approval by writing /approve in a comment
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-01-20 08:05:06.376863775 +0000 UTC m=+481133.990820631: ☑️ agreed by asddongmen.
• 2026-02-02 06:22:20.531951896 +0000 UTC m=+75211.633350608: ☑️ agreed by hongyunyan.

[wk989898]

/retest

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #12515.
But this PR has conflicts, please resolve them!