Failpoint debug fix handle alter add default current timestamp

[haiboumich]

What problem does this PR solve?

Issue Number: close #xxx

What is changed and how it works?

Check List

Tests

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

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[ti-chi-bot]

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[gemini-code-assist]

Summary of Changes

Hello @haiboumich, 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 data consistency problem where columns defined with DEFAULT CURRENT_TIMESTAMP in DDLs were not replicating their timestamps accurately. The solution involves meticulously managing the database session's timestamp during DDL execution, ensuring that the CURRENT_TIMESTAMP function evaluates to the precise time it was executed on the source system. This enhancement significantly improves the reliability of DDL replication for time-sensitive column definitions.

Highlights

• Correct DDL Replication for CURRENT_TIMESTAMP: Implemented a fix to ensure that DDL statements involving DEFAULT CURRENT_TIMESTAMP columns are replicated with the original timestamp from the source, rather than the downstream execution time. This addresses a critical data consistency issue for such column types.
• Session Timestamp Management: Introduced robust session timestamp management within the MySQL DDL sink. The session timestamp is now explicitly reset before and after DDL execution to prevent unintended timestamp leakage between operations. For DDLs with DEFAULT CURRENT_TIMESTAMP, the session timestamp is temporarily set to the original DDL event's timestamp.
• New Helper Module for DDL Parsing: Added a new helper.go file containing functions to parse DDL queries, identify columns with CURRENT_TIMESTAMP defaults, and extract their original default values (timestamps) for accurate replication.
• Enhanced Test Coverage: Added dedicated unit tests (mysql_ddl_timestamp_test.go) and a new integration test (ddl_default_current_timestamp) to thoroughly validate the correct handling of CURRENT_TIMESTAMP in DDLs, including scenarios using failpoints to simulate and test specific behaviors.
• Failpoint Integration for Debugging: Integrated several failpoints (MySQLSinkForceSingleConnection, MySQLSinkSkipSetSessionTimestamp, MySQLSinkSkipResetSessionTimestampAfterDDL) to aid in debugging and testing the new timestamp management logic under various conditions.

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[gemini-code-assist]

Code Review

This pull request introduces a fix to correctly handle ALTER TABLE ... ADD COLUMN ... DEFAULT CURRENT_TIMESTAMP DDL statements in the MySQL sink. It achieves this by setting the session TIMESTAMP variable based on the OriginDefaultValue from the DDL's metadata. The implementation includes new helper functions for parsing DDLs and managing timestamps, and the core DDL execution logic is updated to reset, set, and then reset the session timestamp around the DDL query. The changes are well-supported by new unit and integration tests, including failpoint testing for robustness. I've found one minor logging issue that could be improved.

[ti-chi-bot]

[FORMAT CHECKER NOTIFICATION]

Notice: To remove the do-not-merge/needs-linked-issue label, please provide the linked issue number on one line in the PR body, for example: Issue Number: close #123 or Issue Number: ref #456.

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[ti-chi-bot]

@haiboumich: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-error-log-review	6f42244	link	true	/test pull-error-log-review
pull-dm-integration-test	6f42244	link	true	/test pull-dm-integration-test
pull-cdc-integration-pulsar-test	6f42244	link	true	/test pull-cdc-integration-pulsar-test
pull-cdc-integration-mysql-test	6f42244	link	true	/test pull-cdc-integration-mysql-test
pull-cdc-integration-storage-test	6f42244	link	true	/test pull-cdc-integration-storage-test
pull-cdc-integration-kafka-test	6f42244	link	true	/test pull-cdc-integration-kafka-test

Full PR test history. Your PR dashboard.

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