theirix commented on code in PR #21737:
URL: https://github.com/apache/datafusion/pull/21737#discussion_r4188692946
##########
datafusion/catalog/src/information_schema.rs:
##########
@@ -454,118 +455,98 @@ impl InformationSchemaConfig {
}
}
-/// get the arguments and return types of a UDF
-/// returns a tuple of (arg_types, return_type)
+/// Origins used to enumerate the physical types a native type can take
+const RESOLVE_CAST_SOURCES: [DataType; 2] = [DataType::Null,
DataType::LargeUtf8];
+
+/// Build argument fields for `information_schema` to provide possible return
types
+fn resolve_informational_fields(idx: usize, t: &NativeType) ->
Result<Vec<FieldRef>> {
+ // Since native types map to several physical types, resolve it against
+ // ambiguous types to get canonical `DataType`s for the native type
+ let data_types = RESOLVE_CAST_SOURCES
+ .iter()
+ .map(|source| t.default_cast_for(source))
+ .collect::<Result<Vec<DataType>, _>>()?;
+ Ok(data_types
+ .into_iter()
+ .unique()
+ .map(|dt| Arc::new(Field::new(format!("arg_{idx}"), dt, true)))
+ .collect())
+}
+
+/// Function information schema is a set of tuples - argument types and an
optional return type
+type FunctionInformationSchema = BTreeSet<(Vec<String>, Option<String>)>;
+
+/// Get the arguments and return types of a function from its signature
+fn get_args_and_return_types(
+ signature: &Signature,
+ return_field: impl Fn(&[FieldRef]) -> Result<FieldRef>,
+) -> Result<FunctionInformationSchema> {
+ let arg_types = signature.type_signature.get_representative_types();
+ if arg_types.is_empty() {
+ // Edge case if function doesn't have arguments
+ return Ok(BTreeSet::from([(vec![], None)]));
+ }
+ arg_types
+ .into_iter()
+ .map(|arg_types| {
+ // Get possible types for each input arg
+ let arg_fields = arg_types
+ .iter()
+ .enumerate()
+ .map(|(i, t)| resolve_informational_fields(i, t))
+ .collect::<Result<Vec<_>>>()?;
+ // Build combinations of arg types with the return type
+ let return_types = arg_fields
Review Comment:
Added, tests are updated to check `date_trunc` and a new `generate_series`
case
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