C#/Java/Rust: Improve database quality diagnostics query.

[michaelnebel]

No description provided.

[Copilot]

Pull Request Overview

This PR improves the database quality diagnostics message for C# by including specific health metrics in the diagnostic output. The enhancement provides users with concrete percentage values for call targets and expression types to help them better understand database quality issues.

Key changes:

• Enhanced diagnostic message to include specific database health metrics with percentage values
• Refactored the diagnostic creation logic to capture and display both call target and expression type statistics
• Updated expected test outputs to reflect the new message format

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
csharp/ql/src/change-notes/2025-09-04-database-diagnostics.md	Documents the enhancement to include database health metrics in diagnostic messages
csharp/ql/src/Telemetry/DatabaseQualityDiagnostics.ql	Refactors diagnostic logic to capture specific metrics and updates the diagnostic message format
csharp/ql/integration-tests/all-platforms/standalone/DatabaseQualityDiagnostics.expected	Updates expected test output to match the new diagnostic message format

[redsun82]

maybe

Suggested change

	callMsg + ": " + callTargetOk.floor() + ". " + exprMsg + ": " + exprTypeOk.floor() + ". "
	callMsg + ": " + callTargetOk.floor() + "%. " + exprMsg + ": " + exprTypeOk.floor() + "%. "

?

[hvitved]

How about instead:

private predicate diagnostic(string msg, float value, float threshold) {
  CallTargetStatsReport::percentageOfOk(msg, value) and
  threshold = 85
  or
  ExprTypeStatsReport::percentageOfOk(msg, value) and
  threshold = 85
}

private newtype TDbQualityDiagnostic =
  TTheDbQualityDiagnostic() {
    exists(float percentageGood, float threshold |
      diagnostic(_, percentageGood, threshold) and
      percentageGood < threshold
    )
  }

...

private string getDbHealth() {
    result =
      strictconcat(string msg, float value, float threshold |
        diagnostic(msg, value, threshold)
      |
        msg + ": " + value.floor() + " % (threshold " + threshold.floor() + " %)", ". "
      )
  }

[michaelnebel]

Yes, considering the discussion on the posibility of having different thresholds pr metric - then this looks very good.
I will address the review comments for C# and when we have reached consensus, I will update for the other languages as well (in this PR).

[hvitved]

Thanks for fixing.

[hvitved]

Thanks again.