[PR] Fix take on zero-width FixedSizeListArray [arrow-rs]

["1fanwang (via GitHub)" <gi...@apache.org>]

1fanwang opened a new pull request, #10915:
URL: https://github.com/apache/arrow-rs/pull/10915

   # Which issue does this PR close?
   
   - Closes https://github.com/apache/arrow-rs/issues/10914.
   
   # Rationale for this change
   
   `take` returns no rows for a non-nullable `FixedSizeListArray` whose list size
   is zero, regardless of how many indices were requested. With a three-row input
   and indices `[2, 0]`, the result has length 0 instead of 2.
   
   The take kernel rebuilt the result with `FixedSizeListArray::try_new`. That
   constructor cannot infer a row count from an empty child array when there is no
   null buffer, so it defaults to zero.
   
   # What changes are included in this PR?
   
   The kernel now passes `indices.len()` to
   `FixedSizeListArray::try_new_with_length`. For nonzero list sizes this is the
   same length previously derived from the child array. A regression test covers
   the zero-width case.
   
   # Are these changes tested?
   
   Yes.
   
   <details>
   <summary>Raw test output</summary>
   
   ```text
   $ git rev-parse HEAD
   cbbb56bba13c85f36505453b08f22f8ab71b5794
   $ cargo test -p arrow-select --test issue_10914
   test take_preserves_zero_width_fixed_size_list_length ... FAILED
   assertion `left == right` failed
     left: 0
    right: 2
   
   $ git rev-parse HEAD
   b9dac7cfd239766b5d77dfbcb18ca9524bfbeba1
   $ cargo test -p arrow-select
   test result: ok. 418 passed; 0 failed
   test result: ok. 17 passed; 0 failed
   ```
   
   </details>
   
   # Are there any user-facing changes?
   
   `take` now preserves one output row per requested index for zero-width
   `FixedSizeListArray` values. No public API changes.
   


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Re: [PR] Fix take on zero-width FixedSizeListArray [arrow-rs]

["Jefffrey (via GitHub)" <gi...@apache.org>]

Jefffrey merged PR #10915:
URL: https://github.com/apache/arrow-rs/pull/10915


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Re: [PR] Fix take on zero-width FixedSizeListArray [arrow-rs]

["Jefffrey (via GitHub)" <gi...@apache.org>]

Jefffrey commented on PR #10915:
URL: https://github.com/apache/arrow-rs/pull/10915#issuecomment-5467505413

   thanks @1fanwang 


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