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planner: fix a panic during column pruning (#47883) #48812

Merged
merged 6 commits into from
Nov 26, 2023
Merged

planner: fix a panic during column pruning (#47883) #48812

merged 6 commits into from
Nov 26, 2023

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This is an automated cherry-pick of #47883

What problem does this PR solve?

Issue Number: close #47331

Problem Summary:

What is changed and how it works?

Through my investigation, I identified several key points:

  1. The panic occurs during DeriveStats: p.StatsInfo().ColNDVs[selfSchema.Columns[i].UniqueID] = childProfile.RowCount.
  2. There's a discrepancy in the number of expressions and schema columns: the plan has 8 expressions but only 7 columns in the schema.
  3. The logic plan causing the panic is a projection (ID 25), generated by the joinReOrderSolver.
  4. Post-debugging, I noted that the schema undergoes changes after the LogicalProjection.PruneColumns process.
  5. On further debugging the PruneColumns function individually, I discovered that the schema of projection#25 is affected even before it's reached in the process.
  6. This led me to suspect a memory issue. Notably, projection#18 and projection#25 appear to share the same schema memory address (0x14006b557c0).
  7. Consequently, when a column is pruned from projection#18, projection#25 becomes corrupted, leading to a mismatch between expressions and columns.

So I cloned that schema and made sure we didn't have this kind of problem anymore.

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 a panic issue during column pruning

@Rustin170506 @ti-chi-bot
planner: add test for issue 47331
05d4ace 
Signed-off-by: hi-rustin <rustin.liu@gmail.com>
@Rustin170506 @ti-chi-bot
Clone the originalSchema
2f3ec60 
Signed-off-by: hi-rustin <rustin.liu@gmail.com>
@Rustin170506 @ti-chi-bot
Better comment
6fb5f70 
Signed-off-by: hi-rustin <rustin.liu@gmail.com>
@ti-chi-bot ti-chi-bot added release-note Denotes a PR that will be considered when it comes time to generate release notes. size/M Denotes a PR that changes 30-99 lines, ignoring generated files. type/cherry-pick-for-release-6.5 This PR is cherry-picked to release-6.5 from a source PR. labels Nov 22, 2023
@ti-chi-bot ti-chi-bot mentioned this pull request Nov 22, 2023
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@ti-chi-bot ti-chi-bot added the cherry-pick-approved Cherry pick PR approved by release team. label Nov 23, 2023
@ti-chi-bot ti-chi-bot bot added needs-1-more-lgtm Indicates a PR needs 1 more LGTM. approved labels Nov 24, 2023
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/retest

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ti-chi-bot bot commented Nov 24, 2023

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hi-rustin, qw4990

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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 Nov 24, 2023
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ti-chi-bot bot commented Nov 24, 2023

[LGTM Timeline notifier]

Timeline:

  • 2023-11-24 06:12:03.506126345 +0000 UTC m=+557552.171352543: ☑️ agreed by hi-rustin.
  • 2023-11-24 06:17:06.823128062 +0000 UTC m=+557855.488354256: ☑️ agreed by qw4990.

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/retest

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/retest

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/retest

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/retest

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/retest

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/retest

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/retest

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winoros commented Nov 24, 2023

/retest

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/retest

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/retest

Oh man

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winoros commented Nov 25, 2023

/retest

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/retest

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Add new line
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/retest

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Sleep a while
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/hold

Testing

@ti-chi-bot ti-chi-bot bot added the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Nov 26, 2023
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/retest

@hawkingrei
update
9be51ea 
Signed-off-by: Weizhen Wang <wangweizhen@pingcap.com>
@ti-chi-bot ti-chi-bot bot added size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. and removed size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Nov 26, 2023
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Codecov Report

❗ No coverage uploaded for pull request base (release-6.5@4d64ba0). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files 
@@               Coverage Diff                @@
##             release-6.5     #48812   +/-   ##
================================================
  Coverage               ?   73.6353%           
================================================
  Files                  ?       1087           
  Lines                  ?     349373           
  Branches               ?          0           
================================================
  Hits                   ?     257262           
  Misses                 ?      75596           
  Partials               ?      16515

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@hi-rustin Can you remove the hold?

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/unhold

@ti-chi-bot ti-chi-bot bot removed the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Nov 26, 2023
@ti-chi-bot ti-chi-bot bot merged commit 5396730 into pingcap:release-6.5 Nov 26, 2023
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