mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-14 18:32:29 +00:00
130 lines
4.9 KiB
C++
130 lines
4.9 KiB
C++
#include <Functions/FunctionsDecimalArithmetics.h>
|
|
#include <Functions/FunctionFactory.h>
|
|
|
|
namespace DB
|
|
{
|
|
|
|
namespace
|
|
{
|
|
|
|
struct MultiplyDecimalsImpl
|
|
{
|
|
static constexpr auto name = "multiplyDecimal";
|
|
|
|
template <typename FirstType, typename SecondType>
|
|
static inline Decimal256
|
|
execute(FirstType a, SecondType b, UInt16 scale_a, UInt16 scale_b, UInt16 result_scale)
|
|
{
|
|
if (a.value == 0 || b.value == 0)
|
|
return Decimal256(0);
|
|
|
|
Int256 sign_a = a.value < 0 ? -1 : 1;
|
|
Int256 sign_b = b.value < 0 ? -1 : 1;
|
|
|
|
std::vector<UInt8> a_digits = DecimalOpHelpers::toDigits(a.value * sign_a);
|
|
std::vector<UInt8> b_digits = DecimalOpHelpers::toDigits(b.value * sign_b);
|
|
|
|
std::vector<UInt8> multiplied = DecimalOpHelpers::multiply(a_digits, b_digits);
|
|
|
|
UInt16 product_scale = scale_a + scale_b;
|
|
while (product_scale < result_scale)
|
|
{
|
|
multiplied.push_back(0);
|
|
++product_scale;
|
|
}
|
|
|
|
while (product_scale > result_scale&& !multiplied.empty())
|
|
{
|
|
multiplied.pop_back();
|
|
--product_scale;
|
|
}
|
|
|
|
if (multiplied.empty())
|
|
return Decimal256(0);
|
|
|
|
if (multiplied.size() > DecimalUtils::max_precision<Decimal256>)
|
|
throw DB::Exception("Numeric overflow: result bigger that Decimal256", ErrorCodes::DECIMAL_OVERFLOW);
|
|
|
|
return Decimal256(sign_a * sign_b * DecimalOpHelpers::fromDigits(multiplied));
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
REGISTER_FUNCTION(MultiplyDecimals)
|
|
{
|
|
factory.registerFunction<FunctionsDecimalArithmetics<MultiplyDecimalsImpl>>(Documentation(
|
|
R"(
|
|
Performs multiplication on two decimals. Result value will be of type [Decimal256](../../sql-reference/data-types/decimal.md).
|
|
Result scale can be explicitly specified by `result_scale` argument (const Integer in range `[0, 76]`). If not specified, the result scale is the max scale of given arguments.
|
|
|
|
:::note
|
|
These functions work significantly slower than usual `multiply`.
|
|
In case you don't really need controlled precision and/or need fast computation, consider using [multiply](#multiply)
|
|
:::
|
|
|
|
**Syntax**
|
|
|
|
```sql
|
|
multiplyDecimal(a, b[, result_scale])
|
|
```
|
|
|
|
**Arguments**
|
|
|
|
- `a` — First value: [Decimal](../../sql-reference/data-types/decimal.md).
|
|
- `b` — Second value: [Decimal](../../sql-reference/data-types/decimal.md).
|
|
- `result_scale` — Scale of result: [Int/UInt](../../sql-reference/data-types/int-uint.md).
|
|
|
|
**Returned value**
|
|
|
|
- The result of multiplication with given scale.
|
|
|
|
Type: [Decimal256](../../sql-reference/data-types/decimal.md).
|
|
|
|
**Example**
|
|
|
|
```text
|
|
┌─multiplyDecimal(toDecimal256(-12, 0), toDecimal32(-2.1, 1), 1)─┐
|
|
│ 25.2 │
|
|
└────────────────────────────────────────────────────────────────┘
|
|
```
|
|
|
|
**Difference from regular multiplication:**
|
|
```sql
|
|
SELECT toDecimal64(-12.647, 3) * toDecimal32(2.1239, 4);
|
|
SELECT toDecimal64(-12.647, 3) as a, toDecimal32(2.1239, 4) as b, multiplyDecimal(a, b);
|
|
```
|
|
|
|
```text
|
|
┌─multiply(toDecimal64(-12.647, 3), toDecimal32(2.1239, 4))─┐
|
|
│ -26.8609633 │
|
|
└───────────────────────────────────────────────────────────┘
|
|
┌─multiplyDecimal(toDecimal64(-12.647, 3), toDecimal32(2.1239, 4))─┐
|
|
│ -26.8609 │
|
|
└──────────────────────────────────────────────────────────────────┘
|
|
```
|
|
|
|
```sql
|
|
SELECT
|
|
toDecimal64(-12.647987876, 9) AS a,
|
|
toDecimal64(123.967645643, 9) AS b,
|
|
multiplyDecimal(a, b);
|
|
SELECT
|
|
toDecimal64(-12.647987876, 9) AS a,
|
|
toDecimal64(123.967645643, 9) AS b,
|
|
a * b;
|
|
```
|
|
|
|
```text
|
|
┌─────────────a─┬─────────────b─┬─multiplyDecimal(toDecimal64(-12.647987876, 9), toDecimal64(123.967645643, 9))─┐
|
|
│ -12.647987876 │ 123.967645643 │ -1567.941279108 │
|
|
└───────────────┴───────────────┴───────────────────────────────────────────────────────────────────────────────┘
|
|
Received exception from server (version 22.11.1):
|
|
Code: 407. DB::Exception: Received from localhost:9000. DB::Exception: Decimal math overflow: While processing toDecimal64(-12.647987876, 9) AS a, toDecimal64(123.967645643, 9) AS b, a * b. (DECIMAL_OVERFLOW)
|
|
```
|
|
)"));
|
|
|
|
}
|
|
|
|
}
|