jcsherin commented on code in PR #12374:
URL: https://github.com/apache/datafusion/pull/12374#discussion_r1763245501
##########
datafusion/expr/src/expr_schema.rs:
##########
@@ -499,6 +455,76 @@ impl ExprSchemable for Expr {
}
}
+impl Expr {
+ /// Common method for window functions that applies type coercion
+ /// to all arguments of the window function to check if it matches
+ /// its signature.
+ ///
+ /// If successful, this method returns the data type and
+ /// nullability of the window function's result.
+ ///
+ /// Otherwise, returns an error if there's a type mismatch between
+ /// the window function's signature and the provided arguments.
+ fn data_type_and_nullable_with_window_function(
+ &self,
+ schema: &dyn ExprSchema,
+ window_function: &WindowFunction,
+ ) -> Result<(DataType, bool)> {
+ let WindowFunction { fun, args, .. } = window_function;
+
+ let data_types = args
+ .iter()
+ .map(|e| e.get_type(schema))
+ .collect::<Result<Vec<_>>>()?;
+ match fun {
+ WindowFunctionDefinition::BuiltInWindowFunction(window_fun) => {
+ let return_type = window_fun.return_type(&data_types)?;
+ let nullable =
+ !["RANK", "NTILE",
"CUME_DIST"].contains(&window_fun.name());
+ Ok((return_type, nullable))
+ }
+ WindowFunctionDefinition::AggregateUDF(udaf) => {
+ let new_types = data_types_with_aggregate_udf(&data_types,
udaf)
+ .map_err(|err| {
+ plan_datafusion_err!(
+ "{} {}",
+ err,
+ utils::generate_signature_error_msg(
+ fun.name(),
+ fun.signature(),
+ &data_types
+ )
+ )
+ })?;
+
+ let return_type = udaf.return_type(&new_types)?;
+ let nullable = udaf.is_nullable();
+
+ Ok((return_type, nullable))
+ }
+ WindowFunctionDefinition::WindowUDF(udwf) => {
+ let new_types =
+ data_types_with_window_udf(&data_types,
udwf).map_err(|err| {
+ plan_datafusion_err!(
+ "{} {}",
+ err,
+ utils::generate_signature_error_msg(
+ fun.name(),
+ fun.signature(),
+ &data_types
+ )
+ )
+ })?;
+ let (_, function_name) = self.qualified_name();
Review Comment:
Use `Expr::qualified_name` which also handles:
- `Expr::Column` and,
- `Expr::Alias`
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