[BugFix] fix arrow flight empty set column name is 'r'

[Wenjun7J]

Why I'm doing:

For query return empty set, like select * from table.t1 limit 0, this will return column name 'r' , 'r'.

The column name is set as 'r' to be a placeholder. But if no data arrived, the jdbc driver will not replace it with correct names.

What I'm doing:

Print the correct column schema. But the jdbc driver still has a bug and will return double column names. apache/arrow-java#44
Fixes #issue

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
  • This pr needs auto generate documentation
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 4.1
  • 4.0
  • 3.5
  • 3.4

[CelerData-Reviewer]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 7889511be5

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[github-actions]

[Java-Extensions Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

[FE Incremental Coverage Report]

✅ pass : 31 / 32 (96.88%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
🔵	com/starrocks/service/arrow/flight/sql/ArrowFlightSqlServiceImpl.java	31	32	96.88%	[917]

[github-actions]

[BE Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[Copilot]

Pull request overview

This PR fixes Arrow Flight SQL createPreparedStatement returning a placeholder column name (e.g., "r") for queries that produce empty result sets, by deriving and returning the analyzed output schema (column names/types) instead of a hard-coded placeholder.

Changes:

• Update createPreparedStatement to analyze query statements and build an Arrow Schema from analyzed output expressions.
• Add placeholder-schema fallback for non-query statements / analysis failures.
• Extend unit tests to validate analyzed schema output, fallback behavior, and that ConnectContext thread-local state is restored.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
fe/fe-core/src/main/java/com/starrocks/service/arrow/flight/sql/ArrowFlightSqlServiceImpl.java	Build prepared-statement dataset schema from analyzed query output instead of returning a placeholder "r" schema.
fe/fe-core/src/test/java/com/starrocks/service/arrow/flight/sql/ArrowFlightSqlServiceImplTest.java	Add tests asserting prepared-statement schema matches analyzed columns/types and that thread-local ConnectContext is restored.

[github-actions]

@Mergifyio backport branch-4.1

[github-actions]

@Mergifyio backport branch-4.0

[mergify]

backport branch-4.1

✅ Backports have been created

Details

• #71632 [BugFix] fix arrow flight empty set column name is 'r' (backport #71534) has been created for branch branch-4.1

[mergify]

backport branch-4.0

✅ Backports have been created

Details

• #71633 [BugFix] fix arrow flight empty set column name is 'r' (backport #71534) has been created for branch branch-4.0 but encountered conflicts

Cherry-pick of 2535348 has failed:

On branch mergify/bp/branch-4.0/pr-71534
Your branch is up to date with 'origin/branch-4.0'.

You are currently cherry-picking commit 25353486f7.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   fe/fe-core/src/test/java/com/starrocks/service/arrow/flight/sql/ArrowFlightSqlServiceImplTest.java

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   fe/fe-core/src/main/java/com/starrocks/service/arrow/flight/sql/ArrowFlightSqlServiceImpl.java

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally