[ChangRui-Ryan]

What problem does this PR solve?

Issue Number: close #xxx

Problem Summary:

What is changed and how it works?

Proposal: xxx

What's Changed:

How it Works:

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch

Summary by CodeRabbit

• New Features
  • Hash-join statistics now include the number of row pairs matched on join keys before other conditions are applied. This metric may be unavailable for hash aggregation and may count only the first match in some semi/anti joins.

[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: c4c44497-1e83-4336-bb88-c2b2c018d991

📥 Commits

Reviewing files that changed from the base of the PR and between 59b6783 and c85a02a.

⛔ Files ignored due to path filters (2)

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

📒 Files selected for processing (1)

• proto/executor.proto

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📝 Walkthrough

The TiFlashHashTableStats message adds the optional joined_rows field, with documentation defining its count and reporting scope.

Changes: Hash Join Statistics

Layer / File(s)	Summary
Add joined-row statistics field proto/executor.proto	Adds optional field joined_rows with field number 4. Its comment defines the count, notes possible first-match counting for some semi/anti joins, and states that hash aggregation does not report it.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Feature

Suggested reviewers: windtalker

Merge Risk: ⚪ Minimal · up to c85a0

The optional statistics field preserves existing metrics, and absent values read as zero. No concrete compatibility or behavior regression is established, so the change appears mergeable after normal checks.

### Architecture Summary

Architecture risk: 🔵 Low · up to c85a0

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/executor.proto: TiFlashHashTableStats adds optional joined_rows field 4. Its comments define the count as equi-key-matched probe/build row pairs before other conditions, note the first-match behavior possible for semi/anti joins without other conditions, and limit reporting to hash joins rather than hash aggregation.

Pre-merge checks · 4 · 1

Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check		The description only repeats the repository template. It provides no problem summary, issue information, change details, implementation details, or related-change decisions.	Complete the required sections. Describe the problem, explain the addition of joined_rows and its semantics, provide implementation details, and state whether related documentation updates or release-branch cherry-picking are required.

Passed checks (4 passed)

Check name	Status	Explanation
Title check		The title clearly identifies the main change: adding joined_rows to TiFlash hash table statistics. It is concise and specific.
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.

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✨ Finishing Touches

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Warning

Some tools did not complete. Review the errors below.

🔧 Buf (1.73.0)

Lint configuration: default MINIMAL rules with the repository root as the protobuf import root; no repository Buf configuration was found. These results do not establish the project's lint policy or build configuration. For unresolved imports or symbols, check the project's declared import roots and dependencies before concluding that its build fails.

proto/executor.proto

fatal: unable to access 'https://github.com/pingcap/tipb.git/': Failed to connect to github.com:443 over proxy 127.0.0.1 after 0 ms: Could not connect to server
fatal: could not fetch b2e6024fd8ad483950bae478c3371425c37314ad from promisor remote

CODERABBIT_BUF_COMPATIBILITY_PHASE=materialize-base

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_{A rabbit reads the row count clear,
New joined pairs are noted here.
Before conditions shape the view,
The field records what keys match true.
Then hops away with stats in tow.}

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

[windtalker]

lgtm