evalengine: Fix JSON Path support for same-value ranges.

[arthurschreiber]

Description

The JSON Path implementation used by the eval engine did not properly support single index path ranges (like $[0 to 0]). It also did not support JSON Paths that included last at the end of the range when matched against non-array values.

This pull request attempts to fix both of these issues.

I think this should be backported? 🤔

Related Issue(s)

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

AI Disclosure

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

New flags

• Is this flag really necessary?
• Flag names must be clear and intuitive, use dashes (-), and have a clear help text.

If a workflow is added or modified:

• Each item in Jobs should be named in order to mark it as required.
• If the workflow needs to be marked as required, the maintainer team must be notified.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[arthurschreiber]

I had to add a new json path kind here. Previously offset0 and offset1 were used to distinguish between an array offset and an array range, but this does not work for things like $[0 to 0] or $[last to last]. So I figured adding a separate kind is simpler and cleaner.

[codecov]

Codecov Report

❌ Patch coverage is 70.96774% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.83%. Comparing base (9461e71) to head (ff62f88).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
go/mysql/json/json_path.go	70.96%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #19020      +/-   ##
==========================================
+ Coverage   69.81%   69.83%   +0.02%     
==========================================
  Files        1610     1610              
  Lines      215362   215390      +28     
==========================================
+ Hits       150358   150427      +69     
+ Misses      65004    64963      -41     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[promptless]

📝 Documentation updates detected!

New suggestion: Add changelog entry for JSON Path same-value range fix