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executor: reset all state when table reader executor close (#33219) #33227

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merged 4 commits into from
Apr 27, 2022

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@ti-srebot ti-srebot commented Mar 18, 2022

cherry-pick #33219 to release-5.4
You can switch your code base to this Pull Request by using git-extras:

# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/33227

After apply modifications, you can push your change to this PR via:

git push [email protected]:ti-srebot/tidb.git pr/33227:release-5.4-64b057dea2e9

What problem does this PR solve?

Issue Number: close #33214

Problem Summary:

What is changed and how it works?

When there is a Apply executor, it may Open/Close its children executor several times.

mysql> explain select col from t t1 where (select count(*) from t t2 where t2.col = t1.col or t2.col =  'sdf') > 1;
+------------------------------------+---------+-----------+---------------+-------------------------------------------------------+
| id                                 | estRows | task      | access object | operator info                                         |
+------------------------------------+---------+-----------+---------------+-------------------------------------------------------+
| Projection_13                      | 5.00    | root      |               | test.t.col                                            |
| └─Apply_15                         | 5.00    | root      |               | CARTESIAN inner join                                  |
|   ├─UnionScan_16(Build)            | 5.00    | root      |               |                                                       |
|   │ └─TableReader_18               | 5.00    | root      |               | data:TableFullScan_17                                 |
|   │   └─TableFullScan_17           | 5.00    | cop[tikv] | table:t1      | keep order:false, stats:pseudo                        |
|   └─Selection_19(Probe)            | 0.80    | root      |               | gt(Column#5, 1)                                       |
|     └─StreamAgg_21                 | 1.00    | root      |               | funcs:count(1)->Column#5                              |
|       └─UnionScan_22               | 0.01    | root      |               | or(eq(test.t.col, test.t.col), eq(test.t.col, "sdf")) |
|         └─TableReader_25           | 0.01    | root      |               | data:Selection_24                                     |
|           └─Selection_24           | 0.01    | cop[tikv] |               | or(eq(test.t.col, test.t.col), eq(test.t.col, "sdf")) |
|             └─TableFullScan_23     | 5.00    | cop[tikv] | table:t2      | keep order:false, stats:pseudo                        |
+------------------------------------+---------+-----------+---------------+-------------------------------------------------------+
11 rows in set (0.00 sec)

So it's important that after Open/Close, the executor can be reused.
However, the table reader doen't reset its keyRange and when UnionScan Open/Close it will get repeated keyRange.
And finally return wrong result to its parent executor.

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

None

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ti-chi-bot commented Mar 18, 2022

[REVIEW NOTIFICATION]

This pull request has been approved by:

  • ichn-hu
  • lcwangchao

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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/run-all-tests

@ti-chi-bot ti-chi-bot added do-not-merge/release-note-label-needed Indicates that a PR should not merge because it's missing one of the release note labels. release-note-none Denotes a PR that doesn't merit a release note. and removed do-not-merge/release-note-label-needed Indicates that a PR should not merge because it's missing one of the release note labels. labels Mar 18, 2022
@ti-srebot ti-srebot added size/M Denotes a PR that changes 30-99 lines, ignoring generated files. type/5.4-cherry-pick labels Mar 18, 2022
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@tiancaiamao you're already a collaborator in bot's repo.

@ti-chi-bot ti-chi-bot added size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. and removed size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Mar 18, 2022
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@tiancaiamao please resolve conflicts

@ti-chi-bot ti-chi-bot added size/M Denotes a PR that changes 30-99 lines, ignoring generated files. and removed size/XXL Denotes a PR that changes 1000+ lines, ignoring generated files. labels Mar 22, 2022
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Done @ichn-hu

@ti-chi-bot ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label Mar 22, 2022
@ti-chi-bot ti-chi-bot added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Mar 23, 2022
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/merge

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This pull request has been accepted and is ready to merge.

Commit hash: bf320e4

@ti-chi-bot ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Mar 23, 2022
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sre-bot commented Mar 23, 2022

@VelocityLight VelocityLight added cherry-pick-approved Cherry pick PR approved by release team. and removed do-not-merge/cherry-pick-not-approved labels Apr 27, 2022
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/merge

@ti-chi-bot ti-chi-bot merged commit 14e3f6b into pingcap:release-5.4 Apr 27, 2022
@purelind purelind added this to the v5.4.1 milestone Apr 29, 2022
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