Repository navigation
Preserve null lists when projecting a list of structs - #4129
Open
krishan711 wants to merge 4 commits into
Open
krishan711 wants to merge 4 commits into
krishan711 wants to merge 4 commits into
Conversation
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
rambleraptor
suggested changes
Oct 22, 2026
| assert result.column(1).to_pylist() == [[], None, [("b", 2), ("c", None)]] | ||
|
|
||
|
|
||
| def test__to_requested_schema_null_list_of_structs() -> None: |
Collaborator
There was a problem hiding this comment.
Can you write a test that involves LargeListArray inputs? I'm pretty sure this change causes a regression.
LargeListArray.from_arrays refuses a validity mask with sliced offsets, so a sliced large_list of structs raised. Rebase the offsets to start at 0 and slice the values to match, and test list and large_list, whole and sliced.
Author
|
@rambleraptor i see it: a sliced large_list of structs raised "Null bitmap with offsets slice not supported". rebased the offsets to start at 0 and sliced the values to match, and the test now covers list and large_list, whole and sliced. i hope this is what you were looking out for? if not please let me know i can dive deeper 👍 |
This branch has not been deployed
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Rationale for this change
ArrowProjectionVisitor.listrebuilds a list of structs withLargeListArray.from_arrays(list_array.offsets, value_array). That drops the validity mask, so a null list is written as an empty list. This is the list version of #4118, which fixed the same thing for maps.The fix passes
mask=list_array.is_null().Are these changes tested?
Yes.
test__to_requested_schema_null_list_of_structscovers a full batch and a sliced one. It fails without the fix.test_null_list_and_mapasserted[[], [{"test": 1}]]forcol_list_with_struct, with a comment that it should be[None, [{"test": 1}]]once an Arrow issue was fixed. The null was lost by the rebuild here, not by Arrow:from_arrayswas given the offsets but not the validity, and a null list and an empty one share offsets. So the test now asserts[None, [{"test": 1}]].Are there any user-facing changes?
Null lists of structs stay null on write instead of becoming
[].