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Support new decimal types through SQL and fill-out other relatd functionality #17759

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5ff4b5e
SQL stuff
AdamGS Sep 16, 2025
b7273d1
Rest of the stuff
AdamGS Sep 24, 2025
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6 changes: 6 additions & 0 deletions datafusion/common/src/scalar/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1362,6 +1362,12 @@ impl ScalarValue {
DataType::Float16 => ScalarValue::Float16(Some(f16::from_f32(0.0))),
DataType::Float32 => ScalarValue::Float32(Some(0.0)),
DataType::Float64 => ScalarValue::Float64(Some(0.0)),
DataType::Decimal32(precision, scale) => {
ScalarValue::Decimal32(Some(0), *precision, *scale)
}
DataType::Decimal64(precision, scale) => {
ScalarValue::Decimal64(Some(0), *precision, *scale)
}
DataType::Decimal128(precision, scale) => {
ScalarValue::Decimal128(Some(0), *precision, *scale)
}
Expand Down
97 changes: 92 additions & 5 deletions datafusion/expr-common/src/type_coercion/binary.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -351,12 +351,21 @@ fn math_decimal_coercion(
Decimal32(_, _) | Decimal64(_, _) | Decimal128(_, _) | Decimal256(_, _),
Null,
) => Some((lhs_type.clone(), lhs_type.clone())),
// Same variant decimals - no coercion needed
(Decimal32(_, _), Decimal32(_, _))
| (Decimal64(_, _), Decimal64(_, _))
| (Decimal128(_, _), Decimal128(_, _))
| (Decimal256(_, _), Decimal256(_, _)) => {
Some((lhs_type.clone(), rhs_type.clone()))
}
// Cross-variant decimal coercion - choose larger variant with appropriate precision/scale
(Decimal32(_, _), Decimal64(_, _) | Decimal128(_, _) | Decimal256(_, _))
| (Decimal64(_, _), Decimal32(_, _) | Decimal128(_, _) | Decimal256(_, _))
| (Decimal128(_, _), Decimal32(_, _) | Decimal64(_, _) | Decimal256(_, _))
| (Decimal256(_, _), Decimal32(_, _) | Decimal64(_, _) | Decimal128(_, _)) => {
let coerced_type = get_wider_decimal_type_cross_variant(lhs_type, rhs_type)?;
Some((coerced_type.clone(), coerced_type))
}
// Unlike with comparison we don't coerce to a decimal in the case of floating point
// numbers, instead falling back to floating point arithmetic instead
(
Expand Down Expand Up @@ -955,28 +964,106 @@ 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;

// Choose the larger variant between the two input types
match (lhs_type, rhs_type) {
(Decimal32(_, _), Decimal64(_, _)) | (Decimal64(_, _), Decimal32(_, _)) => {
Some(Decimal64(required_precision, s))
}
(Decimal32(_, _), Decimal128(_, _)) | (Decimal128(_, _), Decimal32(_, _)) => {
Some(Decimal128(required_precision, s))
}
(Decimal32(_, _), Decimal256(_, _)) | (Decimal256(_, _), Decimal32(_, _)) => {
Some(Decimal256(required_precision, s))
}
(Decimal64(_, _), Decimal128(_, _)) | (Decimal128(_, _), Decimal64(_, _)) => {
Some(Decimal128(required_precision, s))
}
(Decimal64(_, _), Decimal256(_, _)) | (Decimal256(_, _), Decimal64(_, _)) => {
Some(Decimal256(required_precision, s))
}
(Decimal128(_, _), Decimal256(_, _)) | (Decimal256(_, _), Decimal128(_, _)) => {
Some(Decimal256(required_precision, s))
}
_ => None,
}
}

/// Coerce `lhs_type` and `rhs_type` to a common type.
fn get_common_decimal_type(
decimal_type: &DataType,
other_type: &DataType,
) -> Option<DataType> {
use arrow::datatypes::DataType::*;
match decimal_type {
Decimal32(_, _) | Decimal64(_, _) | Decimal128(_, _) => {
Decimal32(_, _) => {
let other_decimal_type = coerce_numeric_type_to_decimal32(other_type)?;
get_wider_decimal_type(decimal_type, &other_decimal_type)
}
Decimal64(_, _) => {
let other_decimal_type = coerce_numeric_type_to_decimal64(other_type)?;
get_wider_decimal_type(decimal_type, &other_decimal_type)
}
Decimal128(_, _) => {
let other_decimal_type = coerce_numeric_type_to_decimal128(other_type)?;
get_wider_decimal_type(decimal_type, &other_decimal_type)
}
Expand All @@ -988,7 +1075,7 @@ fn get_common_decimal_type(
}
}

/// Returns a `DataType::Decimal128` that can store any value from either
/// Returns a decimal [`DataType`] that can store any value from either
/// `lhs_decimal_type` and `rhs_decimal_type`
///
/// The result decimal type is `(max(s1, s2) + max(p1-s1, p2-s2), max(s1, s2))`.
Expand Down Expand Up @@ -1209,14 +1296,14 @@ fn numerical_coercion(lhs_type: &DataType, rhs_type: &DataType) -> Option<DataTy
}

fn create_decimal32_type(precision: u8, scale: i8) -> DataType {
DataType::Decimal128(
DataType::Decimal32(
DECIMAL32_MAX_PRECISION.min(precision),
DECIMAL32_MAX_SCALE.min(scale),
)
}

fn create_decimal64_type(precision: u8, scale: i8) -> DataType {
DataType::Decimal128(
DataType::Decimal64(
DECIMAL64_MAX_PRECISION.min(precision),
DECIMAL64_MAX_SCALE.min(scale),
)
Expand Down
90 changes: 90 additions & 0 deletions datafusion/expr-common/src/type_coercion/binary/tests/arithmetic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -291,3 +291,93 @@ fn test_coercion_arithmetic_decimal() -> Result<()> {

Ok(())
}

#[test]
fn test_coercion_arithmetic_decimal_cross_variant() -> Result<()> {
let test_cases = [
(
DataType::Decimal32(5, 2),
DataType::Decimal64(10, 3),
DataType::Decimal64(10, 3),
DataType::Decimal64(10, 3),
),
(
DataType::Decimal32(7, 1),
DataType::Decimal128(15, 4),
DataType::Decimal128(15, 4),
DataType::Decimal128(15, 4),
),
(
DataType::Decimal32(9, 0),
DataType::Decimal256(20, 5),
DataType::Decimal256(20, 5),
DataType::Decimal256(20, 5),
),
(
DataType::Decimal64(12, 3),
DataType::Decimal128(18, 2),
DataType::Decimal128(19, 3),
DataType::Decimal128(19, 3),
),
(
DataType::Decimal64(15, 4),
DataType::Decimal256(25, 6),
DataType::Decimal256(25, 6),
DataType::Decimal256(25, 6),
),
(
DataType::Decimal128(20, 5),
DataType::Decimal256(30, 8),
DataType::Decimal256(30, 8),
DataType::Decimal256(30, 8),
),
// Reverse order cases
(
DataType::Decimal64(10, 3),
DataType::Decimal32(5, 2),
DataType::Decimal64(10, 3),
DataType::Decimal64(10, 3),
),
(
DataType::Decimal128(15, 4),
DataType::Decimal32(7, 1),
DataType::Decimal128(15, 4),
DataType::Decimal128(15, 4),
),
(
DataType::Decimal256(20, 5),
DataType::Decimal32(9, 0),
DataType::Decimal256(20, 5),
DataType::Decimal256(20, 5),
),
(
DataType::Decimal128(18, 2),
DataType::Decimal64(12, 3),
DataType::Decimal128(19, 3),
DataType::Decimal128(19, 3),
),
(
DataType::Decimal256(25, 6),
DataType::Decimal64(15, 4),
DataType::Decimal256(25, 6),
DataType::Decimal256(25, 6),
),
(
DataType::Decimal256(30, 8),
DataType::Decimal128(20, 5),
DataType::Decimal256(30, 8),
DataType::Decimal256(30, 8),
),
];

for (lhs_type, rhs_type, expected_lhs_type, expected_rhs_type) in test_cases {
test_math_decimal_coercion_rule(
lhs_type,
rhs_type,
expected_lhs_type,
expected_rhs_type,
);
}

Ok(())
}
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