jacobBaumbach commented on a change in pull request #9806:
URL: https://github.com/apache/arrow/pull/9806#discussion_r610329683
##########
File path: rust/datafusion/src/physical_plan/union.rs
##########
@@ -60,15 +60,31 @@ impl ExecutionPlan for UnionExec {
/// Output of the union is the combination of all output partitions of the
inputs
fn output_partitioning(&self) -> Partitioning {
- // Sums all the output partitions
- let num_partitions = self
- .inputs
+ let intial: Option<Partitioning> = None;
+ self.inputs
.iter()
- .map(|plan| plan.output_partitioning().partition_count())
- .sum();
- // TODO: this loses partitioning info in case of same partitioning
scheme (for example `Partitioning::Hash`)
- // https://issues.apache.org/jira/browse/ARROW-11991
- Partitioning::UnknownPartitioning(num_partitions)
+ .fold(intial, |acc, input| {
+ match (acc, input.output_partitioning()) {
+ (None, partition) => Some(partition),
+ (
+ Some(Partitioning::Hash(mut vector_acc, size_acc)),
+ Partitioning::Hash(vector, size),
+ ) => {
+ vector_acc.append(&mut vector.clone());
Review comment:
So I added `PartialEq` and ensured all structs that impl `PhysicalExpr`
also `impl PartialEq`. For every occurrence of `Arc<dyn PhysicalExpr>` I get
the following error, 132 times:
```bash
error[E0038]: the trait `PhysicalExpr` cannot be made into an object
--> datafusion/src/physical_plan/udf.rs:95:17
|
95 | args: &[Arc<dyn PhysicalExpr>],
| ^^^^^^^^^^^^^^^^ `PhysicalExpr` cannot be made into an
object
|
note: for a trait to be "object safe" it needs to allow building a vtable to
allow the call to be resolvable dynamically; for more information visit
<https://doc.rust-lang.org/reference/items/traits.html#object-safety>
--> datafusion/src/physical_plan/mod.rs:188:57
|
188 | pub trait PhysicalExpr: Send + Sync + Display + Debug + PartialEq {
| ------------ ^^^^^^^^^
...because it uses `Self` as a type parameter
| |
| this trait cannot be made into an object...
```
It appears that the inclusion of PartialEq makes it so `PhysicalExpr`
doesn't play nicely with dynamic dispatch. Due to PartialEq taking a type arg
of `Self`, which can't be determined under dynamic dispatch. I am not sure how
to work around this.
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