planner: out of range for sampling | tidb-test=pr/2381

[terry1purcell]

What problem does this PR solve?

Issue Number: close #55199

Problem Summary:

What changed and how does it work?

Sampling can result in values being missed for TopN and histogram bucket determination. While TopN may not be affected significantly, histogram bucket ranges will miss values if the aren't seen. This PR improves range estimation for searches that are at the lower or upper extreme of the valid ranges.

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

[tiprow]

Hi @terry1purcell. Thanks for your PR.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 30 lines in your changes missing coverage. Please review.

Project coverage is 56.1602%. Comparing base (83c4a0f) to head (b38d44b).

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #55512         +/-   ##
=================================================
- Coverage   73.3976%   56.1602%   -17.2374%     
=================================================
  Files          1629       1778        +149     
  Lines        450073     636879     +186806     
=================================================
+ Hits         330343     357673      +27330     
- Misses        99467     254609     +155142     
- Partials      20263      24597       +4334     

Flag	Coverage Δ
integration	24.2945% <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	52.3614% <ø> (+6.8146%)	⬆️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[ti-chi-bot]

PR needs rebase.

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[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/mysql-test	b38d44b	link	true	/test mysql-test
idc-jenkins-ci-tidb/check_dev	b38d44b	link	true	/test check-dev
idc-jenkins-ci-tidb/unit-test	b38d44b	link	true	/test unit-test
idc-jenkins-ci-tidb/check_dev_2	b38d44b	link	true	/test check-dev2

Full PR test history. Your PR dashboard.

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