[I] Row converter erases list lengths of `List(Null)` [arrow-rs]

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

kawadakk opened a new issue, #7164:
URL: https://github.com/apache/arrow-rs/issues/7164

   **Describe the bug**
   `RowConverter::convert_rows` always decodes `List(Null)` as empty lists. 
   
   **To Reproduce**
   ```rust
   let mut builder = GenericListBuilder::<O, _>::new(NullBuilder::new());
   builder.values().append_nulls(0);
   builder.append(true);
   builder.append(false);
   builder.values().append_nulls(2);
   builder.append(true);
   
   let list = Arc::new(builder.finish()) as ArrayRef;
   let d = list.data_type().clone();
   
   let converter = RowConverter::new(vec![SortField::new(d.clone())]).unwrap();
   
   let rows = converter.convert_columns(&[Arc::clone(&list)]).unwrap();
   assert!(rows.row(0) > rows.row(1)); // [null] > null
   assert!(rows.row(0) < rows.row(2)); // [null] < [null, null]
   assert!(rows.row(1) < rows.row(2)); // null < [null, null]
   
   let back = converter.convert_rows(&rows).unwrap();
   assert_eq!(back.len(), 1);
   back[0].to_data().validate_full().unwrap();
   assert_eq!(&back[0], &list);
   ```
   
   Adding the above code to `test_single_list` in `arrow-row/src/lib.rs` causes a test failure:
   
   ```
   thread 'tests::test_list' panicked at arrow-row/src/lib.rs:2111:9:
   assertion `left == right` failed
     left: ListArray
   [
     NullArray(0),
     null,
     NullArray(0),
   ]
    right: ListArray
   [
     NullArray(0),
     null,
     NullArray(2),
   ]
   ```
   
   **Expected behavior**
   Not panicking
   
   **Additional context**
   <!--
   Add any other context about the problem here.
   -->


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Re: [I] Row converter does not preserve list lengths of `List(Null)` [arrow-rs]

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

Jefffrey closed issue #7164: Row converter does not preserve list lengths of `List(Null)`
URL: https://github.com/apache/arrow-rs/issues/7164


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Re: [I] Row converter does not preserve list lengths of `List(Null)` [arrow-rs]

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

Jefffrey commented on issue #7164:
URL: https://github.com/apache/arrow-rs/issues/7164#issuecomment-3841902049

   Whoops I should have searched the issues before creating a new one 😅 
   
   I'll close this one as duplicate as we have a PR linked to the other issue (and the other issue also links to the DataFusion issue)


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