AdamGS commented on code in PR #17808:
URL: https://github.com/apache/datafusion/pull/17808#discussion_r2387483319
##########
datafusion/expr-common/src/type_coercion/binary.rs:
##########
@@ -955,28 +963,106 @@ pub fn decimal_coercion(lhs_type: &DataType, rhs_type:
&DataType) -> Option<Data
match (lhs_type, rhs_type) {
// Prefer decimal data type over floating point for comparison
operation
+ (Decimal32(_, _), Decimal32(_, _)) => get_wider_decimal_type(lhs_type,
rhs_type),
+ (Decimal32(_, _), Decimal64(_, _) | Decimal128(_, _) | Decimal256(_,
_)) => {
+ get_wider_decimal_type_cross_variant(lhs_type, rhs_type)
+ }
+ (Decimal32(_, _), _) => get_common_decimal_type(lhs_type, rhs_type),
+ (Decimal64(_, _), Decimal64(_, _)) => get_wider_decimal_type(lhs_type,
rhs_type),
+ (Decimal64(_, _), Decimal32(_, _) | Decimal128(_, _) | Decimal256(_,
_)) => {
+ get_wider_decimal_type_cross_variant(lhs_type, rhs_type)
+ }
+ (Decimal64(_, _), _) => get_common_decimal_type(lhs_type, rhs_type),
(Decimal128(_, _), Decimal128(_, _)) => {
get_wider_decimal_type(lhs_type, rhs_type)
}
+ (Decimal128(_, _), Decimal32(_, _) | Decimal64(_, _) | Decimal256(_,
_)) => {
+ get_wider_decimal_type_cross_variant(lhs_type, rhs_type)
+ }
(Decimal128(_, _), _) => get_common_decimal_type(lhs_type, rhs_type),
- (_, Decimal128(_, _)) => get_common_decimal_type(rhs_type, lhs_type),
(Decimal256(_, _), Decimal256(_, _)) => {
get_wider_decimal_type(lhs_type, rhs_type)
}
+ (Decimal256(_, _), Decimal32(_, _) | Decimal64(_, _) | Decimal128(_,
_)) => {
+ get_wider_decimal_type_cross_variant(lhs_type, rhs_type)
+ }
(Decimal256(_, _), _) => get_common_decimal_type(lhs_type, rhs_type),
+ (_, Decimal32(_, _)) => get_common_decimal_type(rhs_type, lhs_type),
+ (_, Decimal64(_, _)) => get_common_decimal_type(rhs_type, lhs_type),
+ (_, Decimal128(_, _)) => get_common_decimal_type(rhs_type, lhs_type),
(_, Decimal256(_, _)) => get_common_decimal_type(rhs_type, lhs_type),
(_, _) => None,
}
}
+/// Handle cross-variant decimal widening by choosing the larger variant
+fn get_wider_decimal_type_cross_variant(
+ lhs_type: &DataType,
+ rhs_type: &DataType,
+) -> Option<DataType> {
+ use arrow::datatypes::DataType::*;
+
+ let (p1, s1) = match lhs_type {
+ Decimal32(p, s) => (*p, *s),
+ Decimal64(p, s) => (*p, *s),
+ Decimal128(p, s) => (*p, *s),
+ Decimal256(p, s) => (*p, *s),
+ _ => return None,
+ };
+
+ let (p2, s2) = match rhs_type {
+ Decimal32(p, s) => (*p, *s),
+ Decimal64(p, s) => (*p, *s),
+ Decimal128(p, s) => (*p, *s),
+ Decimal256(p, s) => (*p, *s),
+ _ => return None,
+ };
+
+ // max(s1, s2) + max(p1-s1, p2-s2), max(s1, s2)
+ let s = s1.max(s2);
+ let range = (p1 as i8 - s1).max(p2 as i8 - s2);
+ let required_precision = (range + s) as u8;
Review Comment:
I don't think an overflow is valid, I'll have to think about it and maybe
look into solutions in other systems.
We can also just return `None` in that case, which should force the user to
add an explicit cast to one side.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
