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Get the round result for decimal to a decimal with smaller scale #3224

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merged 7 commits into from
Dec 3, 2022
Merged

Get the round result for decimal to a decimal with smaller scale #3224

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a4a49e7
support cast decimal for round when the option is false
liukun4515 Nov 28, 2022
4536283
Merge remote-tracking branch 'upstream/master' into decimal_round_#31…
liukun4515 Nov 29, 2022
01dd8ba
fix conflict after merge
liukun4515 Nov 29, 2022
9a0313e
Merge remote-tracking branch 'upstream/master' into decimal_round_#31…
liukun4515 Nov 30, 2022
d2fa48b
fix error case
liukun4515 Nov 30, 2022
7ee48e2
Merge remote-tracking branch 'upstream/master' into decimal_round_#31…
liukun4515 Dec 1, 2022
477d138
change to wrapping api
liukun4515 Dec 1, 2022
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105 changes: 101 additions & 4 deletions arrow-cast/src/cast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2131,6 +2131,7 @@ fn cast_decimal_to_decimal<const BYTE_WIDTH1: usize, const BYTE_WIDTH2: usize>(
if BYTE_WIDTH1 == 16 {
let array = array.as_any().downcast_ref::<Decimal128Array>().unwrap();
if BYTE_WIDTH2 == 16 {
// the div must be greater or equal than 10
let div = 10_i128
.pow_checked((input_scale - output_scale) as u32)
.map_err(|_| {
Expand All @@ -2139,10 +2140,23 @@ fn cast_decimal_to_decimal<const BYTE_WIDTH1: usize, const BYTE_WIDTH2: usize>(
*output_scale,
))
})?;
let half = div / 2;
let neg_half = -half;

array
.try_unary::<_, Decimal128Type, _>(|v| {
v.checked_div(div).ok_or_else(|| {
// cast to smaller scale, need to round the result
// the div must be gt_eq 10, we don't need to check the overflow for the `div`/`mod` operation
let d = v / div;
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Do we need to make consistent with the usage and clear compilation result?

let r = v % div;
if v >= 0 && r >= half {
d.checked_add(1)
} else if v < 0 && r <= neg_half {
d.checked_sub(1)
} else {
Some(d)
}
.ok_or_else(|| {
ArrowError::CastError(format!(
"Cannot cast to {:?}({}, {}). Overflowing on {:?}",
Decimal128Type::PREFIX,
Expand All @@ -2166,9 +2180,23 @@ fn cast_decimal_to_decimal<const BYTE_WIDTH1: usize, const BYTE_WIDTH2: usize>(
))
})?;

let half = div / i256::from_i128(2_i128);
let neg_half = -half;

array
.try_unary::<_, Decimal256Type, _>(|v| {
i256::from_i128(v).checked_div(div).ok_or_else(|| {
// the div must be gt_eq 10, we don't need to check the overflow for the `div`/`mod` operation
let v = i256::from_i128(v);
let d = v / div;
let r = v % div;
if v >= i256::ZERO && r >= half {
d.checked_add(i256::ONE)
} else if v < i256::ZERO && r <= neg_half {
d.checked_sub(i256::ONE)
} else {
Some(d)
}
.ok_or_else(|| {
ArrowError::CastError(format!(
"Cannot cast to {:?}({}, {}). Overflowing on {:?}",
Decimal256Type::PREFIX,
Expand All @@ -2193,10 +2221,21 @@ fn cast_decimal_to_decimal<const BYTE_WIDTH1: usize, const BYTE_WIDTH2: usize>(
*output_scale,
))
})?;
let half = div / i256::from_i128(2_i128);
let neg_half = -half;
if BYTE_WIDTH2 == 16 {
array
.try_unary::<_, Decimal128Type, _>(|v| {
v.checked_div(div).ok_or_else(|| {
// the div must be gt_eq 10, we don't need to check the overflow for the `div`/`mod` operation
let d = v / div;
let r = v % div;
if v >= i256::ZERO && r >= half {
d.checked_add(i256::ONE)
} else if v < i256::ZERO && r <= neg_half {
d.checked_sub(i256::ONE)
} else {
Some(d)
}.ok_or_else(|| {
ArrowError::CastError(format!(
"Cannot cast to {:?}({}, {}). Overflowing on {:?}",
Decimal128Type::PREFIX,
Expand All @@ -2217,7 +2256,17 @@ fn cast_decimal_to_decimal<const BYTE_WIDTH1: usize, const BYTE_WIDTH2: usize>(
} else {
array
.try_unary::<_, Decimal256Type, _>(|v| {
v.checked_div(div).ok_or_else(|| {
// the div must be gt_eq 10, we don't need to check the overflow for the `div`/`mod` operation
let d = v / div;
let r = v % div;
if v >= i256::ZERO && r >= half {
d.checked_add(i256::ONE)
} else if v < i256::ZERO && r <= neg_half {
d.checked_sub(i256::ONE)
} else {
Some(d)
}
.ok_or_else(|| {
ArrowError::CastError(format!(
"Cannot cast to {:?}({}, {}). Overflowing on {:?}",
Decimal256Type::PREFIX,
Expand Down Expand Up @@ -3588,6 +3637,26 @@ mod tests {
}
}
}

let cast_option = CastOptions { safe: false };
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add cast with safe is false

let casted_array_with_option =
cast_with_options($INPUT_ARRAY, $OUTPUT_TYPE, &cast_option).unwrap();
let result_array = casted_array_with_option
.as_any()
.downcast_ref::<$OUTPUT_TYPE_ARRAY>()
.unwrap();
assert_eq!($OUTPUT_TYPE, result_array.data_type());
assert_eq!(result_array.len(), $OUTPUT_VALUES.len());
for (i, x) in $OUTPUT_VALUES.iter().enumerate() {
match x {
Some(x) => {
assert_eq!(result_array.value(i), *x);
}
None => {
assert!(result_array.is_null(i));
}
}
}
};
}

Expand Down Expand Up @@ -3795,6 +3864,34 @@ mod tests {
result.unwrap_err().to_string());
}

#[test]
fn test_cast_decimal256_to_decimal128_overflow() {
let input_type = DataType::Decimal256(76, 5);
let output_type = DataType::Decimal128(38, 7);
assert!(can_cast_types(&input_type, &output_type));
let array = vec![Some(i256::from_i128(i128::MAX))];
let input_decimal_array = create_decimal256_array(array, 76, 5).unwrap();
let array = Arc::new(input_decimal_array) as ArrayRef;
let result =
cast_with_options(&array, &output_type, &CastOptions { safe: false });
assert_eq!("Invalid argument error: 17014118346046923173168730371588410572700 cannot be casted to 128-bit integer for Decimal128",
result.unwrap_err().to_string());
}

#[test]
fn test_cast_decimal256_to_decimal256_overflow() {
let input_type = DataType::Decimal256(76, 5);
let output_type = DataType::Decimal256(76, 55);
assert!(can_cast_types(&input_type, &output_type));
let array = vec![Some(i256::from_i128(i128::MAX))];
let input_decimal_array = create_decimal256_array(array, 76, 5).unwrap();
let array = Arc::new(input_decimal_array) as ArrayRef;
let result =
cast_with_options(&array, &output_type, &CastOptions { safe: false });
assert_eq!("Cast error: Cannot cast to \"Decimal256\"(76, 55). Overflowing on 170141183460469231731687303715884105727",
result.unwrap_err().to_string());
}

#[test]
fn test_cast_decimal128_to_decimal256() {
let input_type = DataType::Decimal128(20, 3);
Expand Down