tipb: reserve Local MATCH scalar signature

[solotzg]

Summary

• Reserve ScalarFuncSig_LocalMatchAgainstBoolean = 5250 for row-wise Local MATCH Boolean evaluation.
• Keep this PR protocol-only: no query metadata messages, evaluator implementation, or index protocol are added.
• Regenerate the Go binding and update proto.lock for the reserved scalar signature.

The numeric ID is coordinated with the TiDB and TiFlash implementation branches. This reservation alone does not make older binaries execute Local MATCH.

Validation

• GOCACHE=/private/tmp/tipb-go-cache GOWORK=off go test ./go-tipb — passed (package compiles; no test files).
• protolock status -lockdir=scripts -protoroot=proto — passed.
• PR CI run 37879755411 — Go, C++, and Rust generation checks all passed; CLA check passed.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Organization UI
• Review profile: CHILL
• Plan: Advanced
• Run ID: 75bbdc55-5ce6-4f17-acdb-eb05424361ba

📥 Commits

Reviewing files that changed from the base of the PR and between b80b669 and 1f15523.

⛔ Files ignored due to path filters (2)

• go-tipb/expression.pb.go is excluded by !**/*.pb.go
• scripts/proto.lock is excluded by !**/*.lock

📒 Files selected for processing (1)

• proto/expression.proto

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The ScalarFuncSig enum adds LocalMatchAgainstBoolean with numeric ID 5250. Its comment describes row-wise local MATCH evaluation, not index access.

Changes

Local MATCH signature

Layer / File(s)	Summary
Add the signature proto/expression.proto	Adds LocalMatchAgainstBoolean with numeric ID 5250 and documents its row-wise evaluation role.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~3 minutes

Change: Feature

Merge Risk: ⚪ Minimal · up to 1f155

No actionable merge-blocking risk was identified in this protocol-only change.

Architecture Summary

Architecture risk: 🔵 Low · up to 1f155

The change affects 1 system.

Changed systems: proto

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — proto (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

• observed — Modified behavior in proto/expression.proto: ScalarFuncSig adds the LocalMatchAgainstBoolean value with numeric ID 5250 and a comment identifying it as row-wise local MATCH evaluation, not an index access method.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title is concise, specific, and accurately describes the main protocol change: reserving the Local MATCH scalar signature.
Description check		The description clearly states the change scope, implementation boundaries, coordination details, compatibility note, and validation results. It does not use the template headings or explicitly addres…

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_{A rabbit reads the MATCH enum line,
And finds a new signature, neat and fine.
Row by row, the values show,
Not through an index do they go.
The rabbit hops, content with the sign.}

_{Comment @coderabbitai help to get the list of available commands.}