alamb commented on a change in pull request #8032:
URL: https://github.com/apache/arrow/pull/8032#discussion_r476466084
##########
File path: rust/datafusion/src/execution/context.rs
##########
@@ -193,6 +191,17 @@ impl ExecutionContext {
state.scalar_functions.insert(f.name.clone(), Arc::new(f));
}
+ /// Get a reference to the registered scalar functions
+ pub fn scalar_functions(&self) -> Vec<String> {
Review comment:
This is not returning a reference, it is returning a copy
##########
File path: rust/datafusion/src/logicalplan.rs
##########
@@ -1042,6 +998,35 @@ pub fn can_coerce_from(type_into: &DataType, type_from:
&DataType) -> bool {
}
}
+/// A registry of functions used to plan queries programmatically
Review comment:
I wonder what benefit we get from having Registry be its own `struct`
and copying the vec around.
What do you think about something like using a traint. Something like
```
pub trait UDFFactory {
pub fn udf(&self, name: &str, args: Vec<Expr>) -> Result<Expr>;
}
```
And then move the implementation of `udf` directly into ExecutionContext.
##########
File path: rust/datafusion/src/logicalplan.rs
##########
@@ -260,12 +261,10 @@ pub enum Expr {
},
/// scalar function
ScalarFunction {
- /// Name of the function
- name: String,
+ /// The function
+ fun: Box<ScalarFunction>,
Review comment:
```suggestion
fun: Arc<ScalarFunction>,
```
I think you can avoid deep copying the `ScalarFunction` if we use `Arc`
consistently
##########
File path: rust/datafusion/src/sql/planner.rs
##########
@@ -527,9 +527,8 @@ impl<'a, S: SchemaProvider> SqlToRel<'a, S> {
}
Ok(Expr::ScalarFunction {
- name: name.clone(),
+ fun: Box::new(fm.as_ref().clone()),
Review comment:
I think if `fun` was an `Arc` this line will look like `fun: fm.clone()`
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