findepi commented on code in PR #13452:
URL: https://github.com/apache/datafusion/pull/13452#discussion_r1849980264
##########
datafusion/expr-common/src/type_coercion/binary.rs:
##########
@@ -1138,27 +1134,46 @@ fn numeric_string_coercion(lhs_type: &DataType,
rhs_type: &DataType) -> Option<D
}
}
+/// Coerces two fields together, ensuring the field data (name and
nullability) is correctly set.
+fn coerce_list_children(lhs_field: &FieldRef, rhs_field: &FieldRef) ->
Option<FieldRef> {
+ let data_types = vec![lhs_field.data_type().clone(),
rhs_field.data_type().clone()];
+ Some(Arc::new(
+ (**lhs_field)
+ .clone()
+ .with_data_type(type_union_resolution(&data_types)?)
+ .with_nullable(lhs_field.is_nullable() || rhs_field.is_nullable()),
+ ))
+}
+
/// Coercion rules for list types.
fn list_coercion(lhs_type: &DataType, rhs_type: &DataType) -> Option<DataType>
{
use arrow::datatypes::DataType::*;
match (lhs_type, rhs_type) {
- (List(_), List(_)) => Some(lhs_type.clone()),
- (LargeList(_), List(_)) => Some(lhs_type.clone()),
- (List(_), LargeList(_)) => Some(rhs_type.clone()),
- (LargeList(_), LargeList(_)) => Some(lhs_type.clone()),
- (List(_), FixedSizeList(_, _)) => Some(lhs_type.clone()),
- (FixedSizeList(_, _), List(_)) => Some(rhs_type.clone()),
+ (
+ LargeList(lhs_field),
+ List(rhs_field) | LargeList(rhs_field) | FixedSizeList(rhs_field,
_),
Review Comment:
- Let's maybe add listview to the mix. it's hard to test, but why not be
future-proof here?
- let's maybe reorder clauses so that it's clear that any list types are
handled
```rust
match (lhs_type, rhs_type) {
// Coerce to the left side FixedSizeList type if the list lengths
are the same,
// otherwise coerce to list with the left type for dynamic length
(FixedSizeList(lhs_field, ls), FixedSizeList(rhs_field, rs)) if ls
== rs => Some(
FixedSizeList(coerce_list_children(lhs_field, rhs_field)?, *rs),
),
// Left is a LargeList[View] or right is a LargeList[View]
(
LargeList(lhs_field) | LargeListView(lhs_field),
List(rhs_field)
| ListView(rhs_field)
| LargeList(rhs_field)
| LargeListView(rhs_field)
| FixedSizeList(rhs_field, _),
)
| (
List(lhs_field)
| ListView(lhs_field)
| FixedSizeList(lhs_field, _)
| LargeList(lhs_field)
| LargeListView(lhs_field),
LargeList(rhs_field) | LargeListView(rhs_field),
) => Some(LargeList(coerce_list_children(lhs_field, rhs_field)?)),
// Left and right are lists
(
List(lhs_field) | ListView(lhs_field) | FixedSizeList(lhs_field,
_),
List(rhs_field) | ListView(rhs_field) | FixedSizeList(rhs_field,
_),
) => Some(List(coerce_list_children(lhs_field, rhs_field)?)),
_ => None,
}
```
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