parser: modify parser to support partial index

[YangKeao]

What problem does this PR solve?

Issue Number: close #63447

-> #63448
#62759
#62762

Problem Summary:

What changed and how does it work?

Modify the parser to support partial index grammar

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.

None

[codecov]

Codecov Report

❌ Patch coverage is 40.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.6173%. Comparing base (bd7b6f8) to head (66ba465).
⚠️ Report is 17 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #63448        +/-   ##
================================================
+ Coverage   72.7843%   73.6173%   +0.8330%     
================================================
  Files          1835       1839         +4     
  Lines        496868     503252      +6384     
================================================
+ Hits         361642     370481      +8839     
+ Misses       113275     110899      -2376     
+ Partials      21951      21872        -79     

Flag	Coverage Δ
integration	42.8936% <ø> (?)
unit	72.7407% <40.0000%> (+0.4265%)	⬆️

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

Components	Coverage Δ
dumpling	52.8700% <ø> (+0.1132%)	⬆️
parser	∅ <ø> (∅)
br	46.5193% <ø> (+0.0203%)	⬆️

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[YangKeao]

/retest

[bb7133]

LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-09-10 11:18:20.788369206 +0000 UTC m=+446567.348250703: ☑️ agreed by wjhuang2016.
• 2025-09-12 00:54:50.7243239 +0000 UTC m=+581957.284205397: ☑️ agreed by bb7133.

[YangKeao]

I just realized that it needs sig-critical-approvers-parser to approve.

/cc @yudongusa

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bb7133, wjhuang2016, yudongusa

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• pkg/parser/OWNERS [bb7133,yudongusa]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[hawkingrei]

/retest

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #68830.
But this PR has conflicts, please resolve them!