neilconway commented on code in PR #22482:
URL: https://github.com/apache/datafusion/pull/22482#discussion_r3319055553
##########
datafusion/functions/src/math/power.rs:
##########
@@ -582,22 +490,43 @@ impl ScalarUDFImpl for PowerFunc {
)));
}
+ // The simplified expression must keep `return_type`'s declared
+ // type. For example, `power(decimal, float)` returns `Float64`,
+ // so rewriting `power(decimal, 0)` to `1::decimal` or
+ // `power(decimal, 1)` to the decimal base would violate that
+ // contract and trip the optimizer's schema-compatibility check.
+ // Wrap simplified forms in a cast to `return_type` when needed.
+ let return_type =
+ self.return_type(&[base_type.clone(), exponent_type.clone()])?;
+ let needs_cast = |t: &DataType| *t != return_type;
match exponent {
Expr::Literal(value, _)
if value == ScalarValue::new_zero(&exponent_type)? =>
{
Ok(ExprSimplifyResult::Simplified(lit(ScalarValue::new_one(
&base_type,
Review Comment:
Makes sense, done.
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