planner: collect at most NDV-1 TopN | tidb-test=pr/2420

[terry1purcell]

What problem does this PR solve?

Issue Number: close #47400

Problem Summary:

What changed and how does it work?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• 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.

None

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[tiprow]

Hi @terry1purcell. Thanks for your PR.

PRs from untrusted users cannot be marked as trusted with /ok-to-test in this repo meaning untrusted PR authors can never trigger tests themselves. Collaborators can still trigger tests on the PR using /test all.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Project coverage is 55.4639%. Comparing base (ed9a909) to head (6b47e0a).
Report is 148 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #56820         +/-   ##
=================================================
- Coverage   73.2825%   55.4639%   -17.8186%     
=================================================
  Files          1636       1780        +144     
  Lines        453340     635809     +182469     
=================================================
+ Hits         332219     352645      +20426     
- Misses       100768     259577     +158809     
- Partials      20353      23587       +3234     

Flag	Coverage Δ
integration	19.9650% <0.0000%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	52.9478% <ø> (ø)
parser	∅ <ø> (∅)
br	46.3511% <ø> (+0.3599%)	⬆️

[ti-chi-bot]

@terry1purcell: 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
idc-jenkins-ci-tidb/check_dev_2	6b47e0a	link	true	/test check-dev2
idc-jenkins-ci-tidb/mysql-test	6b47e0a	link	true	/test mysql-test
idc-jenkins-ci-tidb/unit-test	6b47e0a	link	true	/test unit-test
idc-jenkins-ci-tidb/check_dev	6b47e0a	link	true	/test check-dev

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[terry1purcell]

Too many testcase changes