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planner, stats: overflow estimation may lead to wrong join reorder (#56752) #56766

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merged 3 commits into from
Oct 23, 2024
Merged

planner, stats: overflow estimation may lead to wrong join reorder (#56752) #56766

merged 3 commits into from
Oct 23, 2024

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This is an automated cherry-pick of #56752

What problem does this PR solve?

Issue Number: close #56704

Problem Summary:

What changed and how does it work?

When the width of the histogram is tooooo large, it's possible that right bound - left bound exceeds MaxFloat64. Then the width becomes inf, and the later calculation is likely to create NaN.

Join reorder uses MaxFloat64 to do the cost comparison, which leads to the wrong order in the above extreme case.

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.

Fix the case that the cost estimation may get INF/NaN in some extreme situations. And fix the wrong join reorder caused by this issue.
修复当代价估算在某些极端情况下估算出 INF/NaN 非法值的问题，以及该问题发生时 join reorder 可能结果出错的问题。

@ti-chi-bot ti-chi-bot added release-note Denotes a PR that will be considered when it comes time to generate release notes. sig/planner SIG: Planner size/L Denotes a PR that changes 100-499 lines, ignoring generated files. type/cherry-pick-for-release-8.4 labels Oct 22, 2024
@ti-chi-bot ti-chi-bot mentioned this pull request Oct 22, 2024
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codecov bot commented Oct 22, 2024 •
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Codecov Report

Attention: Patch coverage is 70.58824% with 5 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-8.4@e7c5e3d). Learn more about missing BASE report.

Additional details and impacted files 
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Flag Coverage Δ
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Flags with carried forward coverage won't be shown. Click here to find out more.

Components Coverage Δ
dumpling 52.9478% <0.0000%> (?)
parser ∅ <0.0000%> (?)
br 52.4488% <0.0000%> (?)

@ti-chi-bot ti-chi-bot bot added approved needs-1-more-lgtm Indicates a PR needs 1 more LGTM. labels Oct 22, 2024
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ti-chi-bot bot commented Oct 22, 2024

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, hawkingrei

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@ti-chi-bot ti-chi-bot bot added lgtm and removed needs-1-more-lgtm Indicates a PR needs 1 more LGTM. labels Oct 22, 2024
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ti-chi-bot bot commented Oct 22, 2024

[LGTM Timeline notifier]

Timeline:

  • 2024-10-22 08:41:48.962902384 +0000 UTC m=+340509.659692991: ☑️ agreed by hawkingrei.
  • 2024-10-22 08:53:21.33863776 +0000 UTC m=+341202.035428390: ☑️ agreed by AilinKid.

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winoros commented Oct 22, 2024

/retest

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@jebter
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jebter commented Oct 22, 2024

/retest

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/retest

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jebter commented Oct 22, 2024

/retest

@ti-chi-bot ti-chi-bot bot merged commit 52b0b58 into pingcap:release-8.4 Oct 23, 2024
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@AilinKid AilinKid AilinKid approved these changes

@hawkingrei hawkingrei hawkingrei approved these changes

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approved cherry-pick-approved Cherry pick PR approved by release team. lgtm release-note Denotes a PR that will be considered when it comes time to generate release notes. sig/planner SIG: Planner size/L Denotes a PR that changes 100-499 lines, ignoring generated files. type/cherry-pick-for-release-8.4
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