Jefffrey commented on code in PR #20012:
URL: https://github.com/apache/datafusion/pull/20012#discussion_r2740365803
##########
datafusion/expr/src/expr_schema.rs:
##########
@@ -598,13 +598,32 @@ impl ExprSchemable for Expr {
)
})?;
- let arguments = args
+ let coerced_values: Vec<Option<ScalarValue>> = args
.iter()
- .map(|e| match e {
- Expr::Literal(sv, _) => Some(sv),
- _ => None,
+ .zip(new_fields.iter())
+ .map(|(expr, field)| {
+ let mut current_expr = expr;
+
+ // Loop to remove all casting layers
+ loop {
+ match current_expr {
+ Expr::Cast(cast) => current_expr = &cast.expr,
+ Expr::TryCast(cast) => current_expr =
&cast.expr,
+ _ => break,
+ }
+ }
+
+ let literal = if let Expr::Literal(sv, _) =
current_expr {
+ Some(sv)
+ } else {
+ None
+ };
+
+ literal.map(|sv|
sv.cast_to(field.data_type())).transpose()
Review Comment:
This is interesting 🤔
So are we essentially looking for all Literals and removing any Cast
expressions, in order to force the cast to happen right here? When does this
happen in relation to type coercion? I ask because I wonder if it's possible to
materialize these casts on literals earlier, or if this is the only place we
can do it?
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