*: small refactor ddl event

[lidezhu]

What problem does this PR solve?

Change Prev** to Extra** and Current** to **.

Issue Number: close #xxx

What is changed and how it works?

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Tests

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This pull-request has been approved by: hongyunyan

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-02-11 08:14:42.168193555 +0000 UTC m=+344324.564415617: ☑️ agreed by hongyunyan.

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