[Variant] Introduce new BorrowedShreddingState concept #8499
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CC @alamb |
scovich
commented
Sep 29, 2025
Comment on lines
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| // Extract value and typed_value fields | ||
| let value = if let Some(value_col) = inner.column_by_name("value") { | ||
| if let Some(binary_view) = value_col.as_binary_view_opt() { | ||
| Some(binary_view.clone()) | ||
| } else { | ||
| return Err(ArrowError::NotYetImplemented(format!( | ||
| "VariantArray 'value' field must be BinaryView, got {}", | ||
| value_col.data_type() | ||
| ))); | ||
| } | ||
| } else { | ||
| None | ||
| }; | ||
| let typed_value = inner.column_by_name("typed_value").cloned(); |
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Now encapsulated by ShreddingState::try_from
| } | ||
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| /// Returns a borrowed version of this shredding state | ||
| pub fn borrow(&self) -> BorrowedShreddingState<'_> { |
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I originally had an impl From instead, but this seems to be more readable/intuitive at call sites.
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Should be a quickie, assuming reviewers agree with the premise. |
alamb
approved these changes
Sep 29, 2025
| self.typed_value.as_ref() | ||
| } | ||
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| /// Returns a borrowed version of this shredding state |
| // Peel away the prefix of path elements that traverses the shredded parts of this variant | ||
| // column. Shredding will traverse the rest of the path on a per-row basis. | ||
| let mut shredding_state = input.shredding_state().clone(); | ||
| let mut shredding_state = input.shredding_state().borrow(); |
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I don't have much to add. FYI @codephage2020 @liamzwbao and @klion26 |
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🚀 |
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Which issue does this PR close?
Struct#8336Rationale for this change
While pathfinding support for unshredding variant objects and arrays, I ran into the same issue that
variant_getalready suffers --ShreddingStateis inconvenient because it owns thevalueandtyped_valuecolumns it refers to, even tho borrowing them usually suffices.What changes are included in this PR?
Define a new
BorrowedShreddingStatewhich does what it says, and updateShreddedPathStep(in variant_get.rs) to use it.Also, make the constructor fallible in order to correctly report casting failures if the
valuecolumn is not a binary view.Are these changes tested?
Yes, existing tests cover this code.
Are there any user-facing changes?
New
TryFromandFromimplementations.impl From<&StructArray> for ShreddingStatewas replaced by a suitableTryFrom.