Flash: add MPP sql digest and connection metadata tracing

[JaySon-Huang]

What problem does this PR solve?

Issue Number: ref pingcap/tidb#66762

rely on pingcap/kvproto#1428

Problem Summary:

• MPP task tracing logs miss SQL digest and connection metadata, making it harder to correlate TiDB session/query information during diagnosis.
• Dispatch logs also do not include SQL digest, reducing observability on request ingress.

What is changed and how it works?

Flash: add MPP sql digest logging and update kvproto
Flash: include connection metadata in MPP task tracing logs

• Plumb TaskMeta.sql_digest into DAGContext and expose it via getter.
• Extend MPP tracing JSON (MPPTaskStatistics::logTracingJson) to print sql_digest, connection_id, and connection_alias.
• Extend FlashService::DispatchMPPTask handling log with sql_digest.
• Update contrib/kvproto submodule pointer to include matched proto changes.

Check List

Tests

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

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

None

Summary by CodeRabbit

Release Notes

• New Features

  • Enhanced diagnostic capabilities with SQL digest tracking to enable improved query identification and monitoring across distributed tasks.
  • Added connection context information (connection ID and alias) to task logging for better request traceability and troubleshooting.

• Chores

  • Updated dependency references.

[pantheon-ai]

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[coderabbitai]

📝 Walkthrough

Walkthrough

This pull request propagates SQL digest and connection context information through the MPP task execution pipeline by introducing new member variables in DAGContext and MPPTaskStatistics to track sql_digest, connection_id, and connection_alias, alongside corresponding logging enhancements.

Changes

Cohort / File(s)	Summary
DAGContext Extension dbms/src/Flash/Coprocessor/DAGContext.h, dbms/src/Flash/Coprocessor/DAGContext.cpp	Added sql_digest member variable and getSQLDigest() accessor to DAGContext; initialized from meta_.sql_digest() in MPP constructor.
MPPTaskStatistics Context Tracking dbms/src/Flash/Mpp/MPPTaskStatistics.h, dbms/src/Flash/Mpp/MPPTaskStatistics.cpp	Added three private members (connection_id, connection_alias, sql_digest) and initialized them from DAGContext in InitializeExecutorDAG; added same fields to JSON tracing log output.
Logging Integration dbms/src/Flash/FlashService.cpp	Extended DispatchMPPTask log message to include sql_digest field and value.
Subproject Update contrib/kvproto	Updated kvproto commit reference (no code changes).

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 A rabbit hops through logs so grand,
With digests swift and context spanned,
Connection threads now traced with care,
Through MPP tasks floating in the air! ✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 37.50% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: adding MPP SQL digest and connection metadata tracing to Flash logs.
Description check	✅ Passed	The pull request description follows the required template with all necessary sections completed, including problem statement, technical changes, commit messages, and checklist.

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✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feature/short-query-sql-digest

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[ti-chi-bot]

[FORMAT CHECKER NOTIFICATION]

Notice: To remove the do-not-merge/needs-linked-issue label, please provide the linked issue number on one line in the PR body, for example: Issue Number: close #123 or Issue Number: ref #456.

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