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fix(expr): round decimal divide result when return type is Int512 (#7035) #7042

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merged 9 commits into from
Mar 15, 2023
Merged

fix(expr): round decimal divide result when return type is Int512 (#7035) #7042

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4a0cbff
This is an automated cherry-pick of #7035
LittleFall Mar 10, 2023
1fc4ccd
Update divide.cpp
LittleFall Mar 13, 2023
c84d7d5
Update gtest_arithmetic_functions.cpp
LittleFall Mar 13, 2023
7f2a5c8
Merge branch 'release-6.1' into cherry-pick-7035-to-release-6.1
ti-chi-bot Mar 13, 2023
3c174b9
Update gtest_arithmetic_functions.cpp
windtalker Mar 14, 2023
9dae31d
Update divide.cpp
windtalker Mar 14, 2023
fa5760d
Merge branch 'release-6.1' into cherry-pick-7035-to-release-6.1
ti-chi-bot Mar 14, 2023
a0d3896
Update gtest_arithmetic_functions.cpp
windtalker Mar 14, 2023
a3a6473
Merge missed fixes for decimal divide
yibin87 Mar 15, 2023
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31 changes: 29 additions & 2 deletions dbms/src/Functions/divide.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,34 @@ struct TiDBDivideFloatingImpl<A, B, false>
template <typename Result = ResultType>
static Result apply(A a, B b)
{
return static_cast<Result>(a) / b;
/// ref https://github.com/pingcap/tiflash/issues/6462
/// For division of Decimal/Decimal or Int/Decimal or Decimal/Int, we should round the result to make compatible with TiDB.
/// basically refer to https://stackoverflow.com/a/71634489
if constexpr (std::is_integral_v<Result> || std::is_same_v<Result, Int256> || std::is_same_v<Result, Int512>)
{
/// 1. do division first, get the quotient and mod, todo:(perf) find a unified `divmod` function to speed up this.
Result quotient = x / d;
Result mod = x % d;
/// 2. get the half of divisor, which is threshold to decide whether to round up or down.
/// note: don't directly use bit operation here, it may cause unexpected result.
Result half = (d / 2) + (d % 2);

/// 3. compare the abstract values of mod and half, if mod >= half, then round up.
Result abs_m = mod < 0 ? -mod : mod;
Result abs_h = half < 0 ? -half : half;
if (abs_m >= abs_h)
{
/// 4. now we need to round up, i.e., add 1 to the quotient's absolute value.
/// if the signs of dividend and divisor are the same, then the quotient should be positive, otherwise negative.
if ((x < 0) == (d < 0)) // same_sign, i.e., quotient >= 0
quotient = quotient + 1;
else
quotient = quotient - 1;
}
return quotient;
}
else
return static_cast<Result>(x) / d;
}
template <typename Result = ResultType>
static Result apply(A a, B b, UInt8 & res_null)
Expand Down Expand Up @@ -332,4 +359,4 @@ void registerFunctionDivideIntegralOrZero(FunctionFactory & factory)
factory.registerFunction<FunctionDivideIntegralOrZero>();
}

} // namespace DB
} // namespace DB
136 changes: 136 additions & 0 deletions dbms/src/Functions/tests/gtest_arithmetic_functions.cpp
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Expand Up @@ -103,6 +103,142 @@ class TestBinaryArithmeticFunctions : public DB::tests::FunctionTest
}
};

template <typename TYPE>
void doTiDBDivideDecimalRoundInternalTest()
{
auto apply = static_cast<TYPE (*)(TYPE, TYPE)>(&TiDBDivideFloatingImpl<TYPE, TYPE, false>::apply);

constexpr TYPE max = std::numeric_limits<TYPE>::max();
// note: Int256's min is not equal to -max-1
// according to https://www.boost.org/doc/libs/1_60_0/libs/multiprecision/doc/html/boost_multiprecision/tut/ints/cpp_int.html
constexpr TYPE min = std::numeric_limits<TYPE>::min();

// clang-format off
const std::vector<std::array<TYPE, 3>> cases = {
{1, 2, 1}, {1, -2, -1}, {-1, 2, -1}, {-1, -2, 1},

{0, 3, 0}, {0, -3, 0}, {0, 3, 0}, {0, -3, 0},
{1, 3, 0}, {1, -3, 0}, {-1, 3, 0}, {-1, -3, 0},
{2, 3, 1}, {2, -3, -1}, {-2, 3, -1}, {-2, -3, 1},
{3, 3, 1}, {3, -3, -1}, {-3, 3, -1}, {-3, -3, 1},
{4, 3, 1}, {4, -3, -1}, {-4, 3, -1}, {-4, -3, 1},
{5, 3, 2}, {5, -3, -2}, {-5, 3, -2}, {-5, -3, 2},

// ±max as divisor
{0, max, 0}, {max/2-1, max, 0}, {max/2, max, 0}, {max/2+1, max, 1}, {max-1, max, 1}, {max, max, 1},
{-1, max, 0}, {-max/2+1, max, 0}, {-max/2, max, 0}, {-max/2-1, max, -1}, {-max+1, max, -1}, {-max, max, -1}, {min, max, -1},
{0, -max, 0}, {max/2-1, -max, 0}, {max/2, -max, 0}, {max/2+1, -max, -1}, {max-1, -max, -1}, {max, -max, -1},
{-1, -max, 0}, {-max/2+1, -max, 0}, {-max/2, -max, 0}, {-max/2-1, -max, 1}, {-max+1, -max, 1}, {-max, -max, 1}, {min, -max, 1},

// ±max as dividend
{max, 1, max}, {max, 2, max/2+1}, {max, max/2-1, 2}, {max, max/2, 2}, {max, max/2+1, 2}, {max, max-1, 1},
{max, -1, -max}, {max, -2, -max/2-1}, {max, -max/2+1, -2}, {max, -max/2, -2}, {max, -max/2-1, -2}, {max, -max+1, -1},
{-max, 1, -max}, {-max, 2, -max/2-1}, {-max, max/2+1, -2}, {-max, max/2, -2}, {-max, max/2-1, -2}, {-max, max-1, -1},
{-max, -1, max}, {-max, -2, max/2+1}, {-max, -max/2-1, 2}, {-max, -max/2, 2}, {-max, -max/2+1, 2}, {-max, -max+1, 1},
};
// clang-format on

for (const auto & expect : cases)
{
std::array<TYPE, 3> actual = {expect[0], expect[1], apply(expect[0], expect[1])};
ASSERT_EQ(expect, actual);
}
}

TEST_F(TestBinaryArithmeticFunctions, TiDBDivideDecimalRoundInternal)
try
{
doTiDBDivideDecimalRoundInternalTest<Int32>();
doTiDBDivideDecimalRoundInternalTest<Int64>();
doTiDBDivideDecimalRoundInternalTest<Int128>();
doTiDBDivideDecimalRoundInternalTest<Int256>();
doTiDBDivideDecimalRoundInternalTest<Int512>();
}
CATCH

TEST_F(TestBinaryArithmeticFunctions, TiDBDivideDecimalRound)
try
{
const String func_name = "tidbDivide";

// decimal32
{
// int and decimal
ASSERT_COLUMN_EQ(
createColumn<Nullable<Decimal64>>(std::make_tuple(18, 4), {DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(0, 4)}),
executeFunction(
func_name,
createColumn<Int32>({1, 1, 1, 1, 1}),
createColumn<Decimal32>(std::make_tuple(20, 4), {DecimalField32(100000000, 4), DecimalField32(100010000, 4), DecimalField32(199990000, 4), DecimalField32(200000000, 4), DecimalField32(200010000, 4)})));

// decimal and decimal
ASSERT_COLUMN_EQ(
createColumn<Nullable<Decimal128>>(std::make_tuple(26, 8), {DecimalField128(10000, 8), DecimalField128(9999, 8), DecimalField128(5000, 8), DecimalField128(5000, 8), DecimalField128(5000, 8)}),
executeFunction(
func_name,
createColumn<Decimal32>(std::make_tuple(18, 4), {DecimalField32(10000, 4), DecimalField32(10000, 4), DecimalField32(10000, 4), DecimalField32(10000, 4), DecimalField32(10000, 4)}),
createColumn<Decimal32>(std::make_tuple(18, 4), {DecimalField32(100000000, 4), DecimalField32(100010000, 4), DecimalField32(199990000, 4), DecimalField32(200000000, 4), DecimalField32(200010000, 4)})));
}

// decimal64
{
// int and decimal
ASSERT_COLUMN_EQ(
createColumn<Nullable<Decimal64>>(std::make_tuple(18, 4), {DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(0, 4)}),
executeFunction(
func_name,
createColumn<Int32>({1, 1, 1, 1, 1}),
createColumn<Decimal64>(std::make_tuple(20, 4), {DecimalField64(100000000, 4), DecimalField64(100010000, 4), DecimalField64(199990000, 4), DecimalField64(200000000, 4), DecimalField64(200010000, 4)})));

// decimal and decimal
ASSERT_COLUMN_EQ(
createColumn<Nullable<Decimal128>>(std::make_tuple(26, 8), {DecimalField128(10000, 8), DecimalField128(9999, 8), DecimalField128(5000, 8), DecimalField128(5000, 8), DecimalField128(5000, 8)}),
executeFunction(
func_name,
createColumn<Decimal64>(std::make_tuple(18, 4), {DecimalField64(10000, 4), DecimalField64(10000, 4), DecimalField64(10000, 4), DecimalField64(10000, 4), DecimalField64(10000, 4)}),
createColumn<Decimal64>(std::make_tuple(18, 4), {DecimalField64(100000000, 4), DecimalField64(100010000, 4), DecimalField64(199990000, 4), DecimalField64(200000000, 4), DecimalField64(200010000, 4)})));
}

// decimal128
{
// int and decimal
ASSERT_COLUMN_EQ(
createColumn<Nullable<Decimal64>>(std::make_tuple(18, 4), {DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(0, 4)}),
executeFunction(
func_name,
createColumn<Int32>({1, 1, 1, 1, 1}),
createColumn<Decimal128>(std::make_tuple(20, 4), {DecimalField128(100000000, 4), DecimalField128(100010000, 4), DecimalField128(199990000, 4), DecimalField128(200000000, 4), DecimalField128(200010000, 4)})));

// decimal and decimal
ASSERT_COLUMN_EQ(
createColumn<Nullable<Decimal128>>(std::make_tuple(26, 8), {DecimalField128(10000, 8), DecimalField128(9999, 8), DecimalField128(5000, 8), DecimalField128(5000, 8), DecimalField128(5000, 8)}),
executeFunction(
func_name,
createColumn<Decimal128>(std::make_tuple(18, 4), {DecimalField128(10000, 4), DecimalField128(10000, 4), DecimalField128(10000, 4), DecimalField128(10000, 4), DecimalField128(10000, 4)}),
createColumn<Decimal128>(std::make_tuple(18, 4), {DecimalField128(100000000, 4), DecimalField128(100010000, 4), DecimalField128(199990000, 4), DecimalField128(200000000, 4), DecimalField128(200010000, 4)})));
}

// decimal256
{
// int and decimal
ASSERT_COLUMN_EQ(
createColumn<Nullable<Decimal64>>(std::make_tuple(18, 4), {DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(1, 4), DecimalField64(0, 4)}),
executeFunction(
func_name,
createColumn<Int32>({1, 1, 1, 1, 1}),
createColumn<Decimal256>(std::make_tuple(20, 4), {DecimalField256(Int256(100000000), 4), DecimalField256(Int256(100010000), 4), DecimalField256(Int256(199990000), 4), DecimalField256(Int256(200000000), 4), DecimalField256(Int256(200010000), 4)})));

// decimal and decimal
ASSERT_COLUMN_EQ(
createColumn<Nullable<Decimal128>>(std::make_tuple(26, 8), {DecimalField128(10000, 8), DecimalField128(9999, 8), DecimalField128(5000, 8), DecimalField128(5000, 8), DecimalField128(5000, 8)}),
executeFunction(
func_name,
createColumn<Decimal256>(std::make_tuple(18, 4), {DecimalField256(Int256(10000), 4), DecimalField256(Int256(10000), 4), DecimalField256(Int256(10000), 4), DecimalField256(Int256(10000), 4), DecimalField256(Int256(10000), 4)}),
createColumn<Decimal256>(std::make_tuple(18, 4), {DecimalField256(Int256(100000000), 4), DecimalField256(Int256(100010000), 4), DecimalField256(Int256(199990000), 4), DecimalField256(Int256(200000000), 4), DecimalField256(Int256(200010000), 4)})));
}
}
CATCH

TEST_F(TestBinaryArithmeticFunctions, TiDBDivideDecimal)
try
{
Expand Down