executor: Fix compact for VARCHAR PK

[breezewish]

What problem does this PR solve?

Issue Number: Fix #51810

Problem Summary:

What changed and how does it work?

When returning the Start key and End key to TiDB, TiFlash does not encode them in a memory comparable way, so that we cannot simply compare these keys.

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 `ALTER TABLE ... COMPACT` may not work for tables with a VARCHAR primary key

[JaySon-Huang]

LGTM

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[JaySon-Huang]

TiFlash does not encode them in a memory comparable way

TiFlash encodes the rowkey with

• a bool to indicate whether it is a common handle
• a varchar to indicate the length of rowkey
• the rowkey

Code: https://github.com/pingcap/tiflash/blob/0d13f398b566c7b06303747b117c3d3af0e5c779/dbms/src/Storages/DeltaMerge/RowKeyRange.h#L238-L242

[codecov]

Codecov Report

Merging #51812 (c400020) into master (1bac1d4) will increase coverage by 3.5474%.
Report is 1 commits behind head on master.
The diff coverage is 0.0000%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #51812        +/-   ##
================================================
+ Coverage   69.2410%   72.7884%   +3.5474%     
================================================
  Files          1476       1476                
  Lines        418158     438083     +19925     
================================================
+ Hits         289537     318874     +29337     
+ Misses       109142      99127     -10015     
- Partials      19479      20082       +603     

Flag	Coverage Δ
integration	48.8212% <0.0000%> (?)
unit	70.4749% <0.0000%> (+1.4711%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9957% <ø> (-2.3014%)	⬇️
parser	∅ <ø> (∅)
br	51.4834% <ø> (+5.0781%)	⬆️

[windtalker]

LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-03-15 06:16:50.332096786 +0000 UTC m=+1011837.354343175: ☑️ agreed by crazycs520.
• 2024-03-15 06:23:40.974120812 +0000 UTC m=+1012247.996367197: ☑️ agreed by windtalker.

[breezewish]

/merge

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[breezewish]

/test unit-test

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/test unit-test

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[breezewish]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: breezewish, crazycs520, JaySon-Huang, windtalker

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[breezewish]

/merge

[ti-chi-bot]

@breezewish: We have migrated to builtin LGTM and approve plugins for reviewing.

Please use /approve when you want approve this pull request.

The changes announcement: LGTM plugin changes

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[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #51817.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #51818.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #51819.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #51820.