Fix IPC roundtripping dicts nested in ListViews #9126
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9 tasks
alamb
approved these changes
Jan 9, 2026
| | DataType::FixedSizeList(field, _) | ||
| | DataType::Map(field, _) => field.fields(), | ||
| DataType::Dictionary(_, value_field) => Field::_fields(value_field.as_ref()), | ||
| DataType::RunEndEncoded(_, field) => field.fields(), |
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I wonder if we should (as a separate PR) add DataType::Union and DataType::Map too 🤔
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looks like it works fine, but doesn't hurt to have some extra tests to ensure it doesn't break: #9146
| assert_eq!(in_batch, out_batch); | ||
| } | ||
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| fn test_roundtrip_list_view_of_dict_impl<OffsetSize: OffsetSizeTrait, U: ArrowNativeType>( |
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I verified these tests fail without the provided code fix
failures:
---- writer::tests::test_roundtrip_large_list_view_of_dict stdout ----
thread 'writer::tests::test_roundtrip_large_list_view_of_dict' (26537286) panicked at arrow-ipc/src/writer.rs:2145:32:
called `Result::unwrap()` on an `Err` value: ParseError("Cannot find a dictionary batch with dict id: 0")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
---- writer::tests::test_roundtrip_list_view_of_dict stdout ----
thread 'writer::tests::test_roundtrip_list_view_of_dict' (26537289) panicked at arrow-ipc/src/writer.rs:2145:32:
called `Result::unwrap()` on an `Err` value: ParseError("Cannot find a dictionary batch with dict id: 0")
---- writer::tests::test_roundtrip_sliced_list_view_of_dict stdout ----
thread 'writer::tests::test_roundtrip_sliced_list_view_of_dict' (26537290) panicked at arrow-ipc/src/writer.rs:2145:32:
called `Result::unwrap()` on an `Err` value: ParseError("Cannot find a dictionary batch with dict id: 0")
failures:
writer::tests::test_roundtrip_large_list_view_of_dict
writer::tests::test_roundtrip_list_view_of_dict
writer::tests::test_roundtrip_sliced_list_view_of_dict
test result: FAILED. 92 passed; 3 failed; 0 ignored; 0 measured; 0 filtered out; finished in 4.73s
44 tasks
Jefffrey
approved these changes
Jan 10, 2026
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alamb
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Jan 13, 2026
# Which issue does this PR close? No known issue, but this confirms that nested dicts do indeed work in Map and Union arrays. It was brought up here: #9126 (comment) # Rationale for this change Ensure that IPC roundtripping nested dicts works in Map and Union arrays. # What changes are included in this PR? Unit tests testing the functionality. # Are these changes tested? The whole PR consists of tests only. # Are there any user-facing changes? No @alamb @Jefffrey
Dandandan
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Jan 15, 2026
# Which issue does this PR close? Closes apache#9125 # Rationale for this change Fixes correct handling of dict building for IPC when ListView is used. # What changes are included in this PR? Creating schemas correctly and reading dict IDs correctly when ListView occurs in IPC. # Are these changes tested? Yes, see new unit tests. # Are there any user-facing changes? No, just a bug fix. @alamb
Dandandan
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Jan 15, 2026
…e#9146) # Which issue does this PR close? No known issue, but this confirms that nested dicts do indeed work in Map and Union arrays. It was brought up here: apache#9126 (comment) # Rationale for this change Ensure that IPC roundtripping nested dicts works in Map and Union arrays. # What changes are included in this PR? Unit tests testing the functionality. # Are these changes tested? The whole PR consists of tests only. # Are there any user-facing changes? No @alamb @Jefffrey
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Which issue does this PR close?
Closes #9125
Rationale for this change
Fixes correct handling of dict building for IPC when ListView is used.
What changes are included in this PR?
Creating schemas correctly and reading dict IDs correctly when ListView occurs in IPC.
Are these changes tested?
Yes, see new unit tests.
Are there any user-facing changes?
No, just a bug fix.
@alamb