(DNM) expression: remove ctx from ParamMarker

[YangKeao]

What problem does this PR solve?

Issue Number: close #53485

Problem Summary:

As every execution will set the correct Constant.Value, there is no need to read the value from session context again.

What changed and how does it work?

Remove the ctx field from ParamMarker. Remove the GetUserVar function, and use Constant.Value as a replacement.

Check List

TODO

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.

None

[ti-chi-bot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[ti-chi-bot]

[FORMAT CHECKER NOTIFICATION]

Notice: To remove the do-not-merge/needs-tests-checked label, please finished the tests then check the finished items in description.

For example:

Tests

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

_{📖 For more info, you can check the "Contribute Code" section in the development guide.}

[tiprow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[YangKeao]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 73.9423%. Comparing base (6928519) to head (5babb90).
Report is 1 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #53487        +/-   ##
================================================
+ Coverage   72.5278%   73.9423%   +1.4144%     
================================================
  Files          1505       1505                
  Lines        429901     429889        -12     
================================================
+ Hits         311798     317870      +6072     
+ Misses        98809      92082      -6727     
- Partials      19294      19937       +643     

Flag	Coverage Δ
integration	23.3806% <0.0000%> (?)

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

Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	50.4028% <ø> (+8.9988%)	⬆️

[tiprow]

@YangKeao: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
fast_test_tiprow	5babb90	link	true	/test fast_test_tiprow

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.

[YangKeao]

When the statement is using plan cache, the Value is not set. Therefore, this PR is not correct. It's only an experiment to see what will happen if I removed it.

[ti-chi-bot]

@YangKeao: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-mysql-client-test	5babb90	link	true	/test pull-mysql-client-test
idc-jenkins-ci-tidb/unit-test	5babb90	link	true	/test unit-test
idc-jenkins-ci-tidb/mysql-test	5babb90	link	true	/test mysql-test
idc-jenkins-ci-tidb/check_dev_2	5babb90	link	true	/test check-dev2
idc-jenkins-ci-tidb/check_dev	5babb90	link	true	/test check-dev

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.