executor: do not acqurie pessimistic lock for non-unique index keys (#36229)

[ti-srebot]

cherry-pick #36229 to release-6.2
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# In tidb repo:
git pr https://github.com/pingcap/tidb/pull/36562

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git push git@github.com:ti-srebot/tidb.git pr/36562:release-6.2-87c5b5068ab8

---

Signed-off-by: ekexium eke@fastmail.com

What problem does this PR solve?

Issue Number: close #36235

Problem Summary:

Fix the condition of checking if the index KV is unique or not.

What is changed and how it works?

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.

bugfix: do not acquire pessimistic lock for non-unique index keys

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• cfzjywxk
• wjhuang2016

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[ti-srebot]

/run-all-tests

[ti-srebot]

@ekexium you're already a collaborator in bot's repo.

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/e3ac9dac88c4243398a155a4cf23c33350990eae

[cfzjywxk]

@tiancaiamao @wjhuang2016 @tangenta PTAL

[cfzjywxk]

/merge

[ti-chi-bot]

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

Commit hash: 2a4c11e

[ti-chi-bot]

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