statistic: fix panic when building topN (#47928)

[ti-chi-bot]

This is an automated cherry-pick of #47928

Signed-off-by: hi-rustin [email protected]

What problem does this PR solve?

Issue Number: close #35948

Problem Summary:

What is changed and how it works?

The issue arises when a value appears twice in the topN list, triggering a panic. The solution involves breaking out of the loop as soon as we find the duplicate value. This bug seems to occur only when the column is of JSON type. Since we haven't been able to reproduce the issue, we've added a warning log to print all topN values, helping us identify the duplicated value.

Check List

Tests

• Unit test
• Integration test
• We will test it on users env.
• No need to test

  • I checked and no code files have been changed.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

Fixed a bug that caused a panic while generating the topN statistics

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-6.5@de507fc). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, hi-rustin

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-10-31 05:38:55.603904572 +0000 UTC m=+2931533.191014732: ☑️ agreed by hi-rustin.
• 2023-10-31 09:14:03.63985083 +0000 UTC m=+2944441.226960978: ☑️ agreed by hawkingrei.