alamb commented on code in PR #3549:
URL: https://github.com/apache/arrow-datafusion/pull/3549#discussion_r976838532
##########
datafusion/expr/src/binary_rule.rs:
##########
@@ -624,19 +627,12 @@ fn eq_coercion(lhs_type: &DataType, rhs_type: &DataType)
-> Option<DataType> {
}
/// coercion rules from NULL type. Since NULL can be casted to most of types
in arrow,
-/// either lhs or rhs is NULL, if NULL can be casted to type of the other
side, the coecion is valid.
+/// either lhs or rhs is NULL, if NULL can be casted to type of the other
side, the coercion is valid.
fn null_coercion(lhs_type: &DataType, rhs_type: &DataType) -> Option<DataType>
{
match (lhs_type, rhs_type) {
- (DataType::Null, _) => {
- if can_cast_types(&DataType::Null, rhs_type) {
- Some(rhs_type.clone())
- } else {
- None
- }
- }
- (_, DataType::Null) => {
- if can_cast_types(&DataType::Null, lhs_type) {
- Some(lhs_type.clone())
+ (DataType::Null, other_type) | (other_type, DataType::Null) => {
Review Comment:
this is a nice cleanup
##########
datafusion/expr/src/binary_rule.rs:
##########
@@ -308,25 +308,18 @@ fn mathematics_numerical_coercion(
(Decimal128(_, _), Decimal128(_, _)) => {
coercion_decimal_mathematics_type(mathematics_op, lhs_type,
rhs_type)
}
- (Decimal128(_, _), _) => {
- let converted_decimal_type =
coerce_numeric_type_to_decimal(rhs_type);
- match converted_decimal_type {
- None => None,
- Some(right_decimal_type) => coercion_decimal_mathematics_type(
- mathematics_op,
- lhs_type,
- &right_decimal_type,
- ),
- }
+ (Null, dec_type @ Decimal128(_, _)) | (dec_type @ Decimal128(_, _),
Null) => {
+ Some(dec_type.clone())
Review Comment:
Could the same coercion (Null to that type) be applied for all the other
numeric types as well?
In other words, I wonder if we need to special case Decimal128 ? Is it to
skip the special decimal coercion logic below?
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