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Fix documentation after #42438

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This commit is contained in:
Alexey Milovidov 2022-12-13 19:13:37 +01:00
parent a4525bb98f
commit bb20733120
4 changed files with 252 additions and 104 deletions
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17
src/Functions/FunctionsDecimalArithmetics.cpp
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@ -1,17 +0,0 @@
#include <Functions/FunctionsDecimalArithmetics.h>
#include <Functions/FunctionFactory.h>
namespace DB
{
REGISTER_FUNCTION(DivideDecimals)
{
factory.registerFunction<FunctionsDecimalArithmetics<DivideDecimalsImpl>>(Documentation(
"Decimal division with given precision. Slower than simple `divide`, but has controlled precision and no sound overflows"));
}
REGISTER_FUNCTION(MultiplyDecimals)
{
factory.registerFunction<FunctionsDecimalArithmetics<MultiplyDecimalsImpl>>(Documentation(
"Decimal multiplication with given precision. Slower than simple `divide`, but has controlled precision and no sound overflows"));
}
}

90
src/Functions/FunctionsDecimalArithmetics.h
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@ -1,4 +1,5 @@
#pragma once
#include <type_traits>
#include <Core/AccurateComparison.h>
@ -140,91 +141,6 @@ struct DecimalOpHelpers
};
struct DivideDecimalsImpl
{
static constexpr auto name = "divideDecimal";
template <typename FirstType, typename SecondType>
static inline Decimal256
execute(FirstType a, SecondType b, UInt16 scale_a, UInt16 scale_b, UInt16 result_scale)
{
if (b.value == 0)
throw DB::Exception("Division by zero", ErrorCodes::ILLEGAL_DIVISION);
if (a.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);
while (scale_a < scale_b + result_scale)
{
a_digits.push_back(0);
++scale_a;
}
while (scale_a > scale_b + result_scale && !a_digits.empty())
{
a_digits.pop_back();
--scale_a;
}
if (a_digits.empty())
return Decimal256(0);
std::vector<UInt8> divided = DecimalOpHelpers::divide(a_digits, b.value * sign_b);
if (divided.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(divided));
}
};
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));
}
};
template <typename ResultType, typename Transform>
struct Processor
{
@ -388,11 +304,12 @@ public:
}
private:
//long resolver to call proper templated func
// long resolver to call proper templated func
ColumnPtr resolveOverload(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type) const
{
WhichDataType which_dividend(arguments[0].type.get());
WhichDataType which_divisor(arguments[1].type.get());
if (which_dividend.isDecimal32())
{
using DividendType = DataTypeDecimal32;
@ -454,4 +371,3 @@ private:
};
}

120
src/Functions/divideDecimal.cpp Normal file
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@ -0,0 +1,120 @@
#include <Functions/FunctionsDecimalArithmetics.h>
#include <Functions/FunctionFactory.h>
namespace DB
{
namespace
{
struct DivideDecimalsImpl
{
static constexpr auto name = "divideDecimal";
template <typename FirstType, typename SecondType>
static inline Decimal256
execute(FirstType a, SecondType b, UInt16 scale_a, UInt16 scale_b, UInt16 result_scale)
{
if (b.value == 0)
throw DB::Exception("Division by zero", ErrorCodes::ILLEGAL_DIVISION);
if (a.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);
while (scale_a < scale_b + result_scale)
{
a_digits.push_back(0);
++scale_a;
}
while (scale_a > scale_b + result_scale && !a_digits.empty())
{
a_digits.pop_back();
--scale_a;
}
if (a_digits.empty())
return Decimal256(0);
std::vector<UInt8> divided = DecimalOpHelpers::divide(a_digits, b.value * sign_b);
if (divided.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(divided));
}
};
}
REGISTER_FUNCTION(DivideDecimals)
{
factory.registerFunction<FunctionsDecimalArithmetics<DivideDecimalsImpl>>(Documentation(
R"(
Performs division 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 function work significantly slower than usual `divide`.
In case you don't really need controlled precision and/or need fast computation, consider using [divide](#divide).
:::
**Syntax**
```sql
divideDecimal(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 division with given scale.
Type: [Decimal256](../../sql-reference/data-types/decimal.md).
**Example**
```text
┌─divideDecimal(toDecimal256(-12, 0), toDecimal32(2.1, 1), 10)─┐
│ -5.7142857142 │
└──────────────────────────────────────────────────────────────┘
```
**Difference from regular division:**
```sql
SELECT toDecimal64(-12, 1) / toDecimal32(2.1, 1);
SELECT toDecimal64(-12, 1) as a, toDecimal32(2.1, 1) as b, divideDecimal(a, b, 1), divideDecimal(a, b, 5);
```
```text
┌─divide(toDecimal64(-12, 1), toDecimal32(2.1, 1))─┐
│ -5.7 │
└──────────────────────────────────────────────────┘
┌───a─┬───b─┬─divideDecimal(toDecimal64(-12, 1), toDecimal32(2.1, 1), 1)─┬─divideDecimal(toDecimal64(-12, 1), toDecimal32(2.1, 1), 5)─┐
│ -12 │ 2.1 │ -5.7 │ -5.71428 │
└─────┴─────┴────────────────────────────────────────────────────────────┴────────────────────────────────────────────────────────────┘
```
```sql
SELECT toDecimal64(-12, 0) / toDecimal32(2.1, 1);
SELECT toDecimal64(-12, 0) as a, toDecimal32(2.1, 1) as b, divideDecimal(a, b, 1), divideDecimal(a, b, 5);
```
```text
DB::Exception: Decimal result's scale is less than argument's one: While processing toDecimal64(-12, 0) / toDecimal32(2.1, 1). (ARGUMENT_OUT_OF_BOUND)
┌───a─┬───b─┬─divideDecimal(toDecimal64(-12, 0), toDecimal32(2.1, 1), 1)─┬─divideDecimal(toDecimal64(-12, 0), toDecimal32(2.1, 1), 5)─┐
│ -12 │ 2.1 │ -5.7 │ -5.71428 │
└─────┴─────┴────────────────────────────────────────────────────────────┴────────────────────────────────────────────────────────────┘
```
)"));
}
}

129
src/Functions/multiplyDecimal.cpp Normal file
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@ -0,0 +1,129 @@
#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)
```
)"));
}
}