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planner: when pushing topN down below proj, check whether topN.ByItems contains a column(with ID=0) generated by proj (#40593) #41178

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This is an automated cherry-pick of #40593

What problem does this PR solve?

Issue Number: close #40535

Problem Summary:

The minimal reproduce step can be simplified to:

CREATE TABLE `t1` (
  `c1` bigint(20) NOT NULL DEFAULT '-2312745469307452950',
  `c2` datetime DEFAULT '5316-02-03 06:54:49',
  `c3` tinyblob DEFAULT NULL,
  PRIMARY KEY (`c1`) /*T![clustered_index] CLUSTERED */
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

CREATE TABLE `t2` (
  `c1` set('kn8pu','7et','vekx6','v3','liwrh','q14','1met','nnd5i','5o0','8cz','l') DEFAULT '7et,vekx6,liwrh,q14,1met',
  `c2` float DEFAULT '1.683167',
  KEY `k1` (`c2`,`c1`),
  KEY `k2` (`c2`)
) ENGINE=InnoDB DEFAULT CHARSET=gbk COLLATE=gbk_chinese_ci;

( select   /*+ agg_to_cop()  */  locate( `t1`.`c3` , `t1`.`c3` ) as r0 , `t1`.`c3` as r1 from `t1` where not( IsNull( `t1`.`c1` ) )   order by r0,r1  ) union all ( select     concat_ws(',', `t2`.`c2` , `t2`.`c1` ) as r0 , `t2`.`c1` as r1 from `t2`    order by r0,r1  ) order by 1 limit 273;

logical plan before logicalOptimize:

*core.LogicalLimit
  *core.LogicalSort
    *core.LogicalUnionAll
      *core.LogicalProjection
        *core.LogicalSort
          *core.LogicalProjection
            *core.DataSource
      *core.LogicalProjection
        *core.LogicalSort
          *core.LogicalProjection
            *core.DataSource   

logical plan after logicalOptimize:

*core.LogicalTopN
  *core.LogicalUnionAll
    *core.LogicalProjection
      *core.LogicalProjection
        *core.LogicalTopN
          *core.DataSource
    *core.LogicalProjection
      *core.LogicalProjection
        *core.LogicalTopN <-
          *core.DataSource

In planner/core/task.go:*PhysicalTopN.attach2TaskTopN.ByItems contains a column that cannot be obtained from copTask.indexPlan, so the optimizer chooses to use copTask.tablePlan, but copTask.tablePlan is nil, this results in "null pointer dereference".

What is changed and how it works?

There is a column in topN.ByItems is generated by proj, when topN is pushed down below proj, topN cannot obtain the column from datasource, to fix this, we can check whether topN.ByItems contains a column(with ID=0) generated by proj, if so, proj will prevent the optimizer from pushing topN down.

  1. A column with ID=0 indicates that the column cannot be resolved by data source.
  2. To determine whether a column is generated by projection, we can check whether the child of proj contains the column.

Check List

Tests

  • Unit test
  • Integration test
  • Manual test (add detailed scripts or steps below)
  • No code

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

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[REVIEW NOTIFICATION]

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@ti-chi-bot ti-chi-bot added do-not-merge/cherry-pick-not-approved release-note-none Denotes a PR that doesn't merit a release note. ok-to-test Indicates a PR is ready to be tested. size/S Denotes a PR that changes 10-29 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 Feb 8, 2023
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/hold high priority for trunk branch

@ti-chi-bot ti-chi-bot added the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Feb 10, 2023
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/unhold

@ti-chi-bot ti-chi-bot removed the do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. label Feb 10, 2023
@ti-chi-bot ti-chi-bot added the cherry-pick-approved Cherry pick PR approved by release team. label Aug 17, 2023
@ti-chi-bot ti-chi-bot bot deleted a comment from ti-chi-bot Aug 17, 2023
@ti-chi-bot ti-chi-bot bot added needs-1-more-lgtm Indicates a PR needs 1 more LGTM. approved labels Aug 17, 2023
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qw4990 commented Aug 17, 2023

/test unit-test

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tiprow bot commented Aug 17, 2023

@qw4990: No presubmit jobs available for pingcap/tidb@release-6.5

In response to this:

/test unit-test

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ti-chi-bot bot commented Aug 17, 2023

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, 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 Aug 17, 2023
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ti-chi-bot bot commented Aug 17, 2023

[LGTM Timeline notifier]

Timeline:

  • 2023-08-17 06:54:47.850222073 +0000 UTC m=+786852.399238055: ☑️ agreed by qw4990.
  • 2023-08-17 06:55:27.78250246 +0000 UTC m=+786892.331518444: ☑️ agreed by hawkingrei.

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codecov bot commented Aug 17, 2023

Codecov Report

❗ No coverage uploaded for pull request base (release-6.5@ce4601b). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files
@@               Coverage Diff                @@
##             release-6.5     #41178   +/-   ##
================================================
  Coverage               ?   77.1157%           
================================================
  Files                  ?       1083           
  Lines                  ?     375896           
  Branches               ?          0           
================================================
  Hits                   ?     289875           
  Misses                 ?      70258           
  Partials               ?      15763           

@ti-chi-bot ti-chi-bot bot merged commit 3dd5949 into pingcap:release-6.5 Aug 17, 2023
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