jonahgao commented on code in PR #11542:
URL: https://github.com/apache/datafusion/pull/11542#discussion_r1684484209
##########
datafusion/expr/src/expr_schema.rs:
##########
@@ -112,7 +112,23 @@ impl ExprSchemable for Expr {
Expr::OuterReferenceColumn(ty, _) => Ok(ty.clone()),
Expr::ScalarVariable(ty, _) => Ok(ty.clone()),
Expr::Literal(l) => Ok(l.data_type()),
- Expr::Case(case) => case.when_then_expr[0].1.get_type(schema),
+ Expr::Case(case) => {
+ let then_type = case.when_then_expr[0].1.get_type(schema)?;
+ if !then_type.is_null() {
+ return Ok(then_type);
+ }
+
+ let else_type = case
+ .else_expr
+ .as_ref()
+ .map_or(Ok(DataType::Null), |e| e.get_type(schema))?;
+
+ match (then_type.clone(), else_type.clone()) {
Review Comment:
```suggestion
match (&then_type, &else_type) {
```
I think we can avoid these clones.
##########
datafusion/expr/src/expr_schema.rs:
##########
@@ -112,7 +112,23 @@ impl ExprSchemable for Expr {
Expr::OuterReferenceColumn(ty, _) => Ok(ty.clone()),
Expr::ScalarVariable(ty, _) => Ok(ty.clone()),
Expr::Literal(l) => Ok(l.data_type()),
- Expr::Case(case) => case.when_then_expr[0].1.get_type(schema),
+ Expr::Case(case) => {
+ let then_type = case.when_then_expr[0].1.get_type(schema)?;
+ if !then_type.is_null() {
+ return Ok(then_type);
+ }
+
+ let else_type = case
+ .else_expr
+ .as_ref()
+ .map_or(Ok(DataType::Null), |e| e.get_type(schema))?;
+
+ match (then_type.clone(), else_type.clone()) {
+ (DataType::Null, DataType::Null) => Ok(DataType::Int64),
Review Comment:
There might be a problem with the following expression.
```sql
CASE data WHEN 1 THEN NULL WHEN 2 THEN 3.3 ELSE NULL END;
```
Its type being float would be more reasonable.
Another more general fix might be to ensure that type coercion has already
been performed before calling `get_type`, but I am not sure if that can be
achieved. Therefore, the current solution is okay for me.
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