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Merged
slabko merged 2 commits into from
Aug 24, 2026
Merged

Validate Decimal precision and scale before swapping #553

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e921d4e
Validate Decimal parameters before swapping
fallintoplace Aug 24, 2026
7dc75ac
Test Decimal precision mismatch with same storage type
fallintoplace Aug 24, 2026
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13 changes: 13 additions & 0 deletions clickhouse/columns/decimal.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -236,6 +236,19 @@ ColumnRef ColumnDecimal::CloneEmpty() const {

void ColumnDecimal::Swap(Column& other) {
auto & col = dynamic_cast<ColumnDecimal &>(other);

if (col.GetPrecision() != GetPrecision()) {
throw ValidationError("Can't swap Decimal columns when precisions are not the same: "
+ std::to_string(GetPrecision()) + "(this) != "
+ std::to_string(col.GetPrecision()) + "(that)");
}

if (col.GetScale() != GetScale()) {
throw ValidationError("Can't swap Decimal columns when scales are not the same: "
+ std::to_string(GetScale()) + "(this) != "
+ std::to_string(col.GetScale()) + "(that)");
}

data_.swap(col.data_);
}

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54 changes: 54 additions & 0 deletions ut/columns_ut.cpp
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Expand Up @@ -184,6 +184,60 @@ TEST(ColumnsCase, DecimalStringAt) {

}

TEST(ColumnsCase, DecimalSwap) {
auto column1 = std::make_shared<ColumnDecimal>(18, 2);
auto column2 = std::make_shared<ColumnDecimal>(18, 2);
column1->Append("1.23");
column2->Append("4.56");

column1->Swap(*column2);

EXPECT_EQ(column1->StringAt(0), "4.56");
EXPECT_EQ(column2->StringAt(0), "1.23");
}

TEST(ColumnsCase, DecimalSwapDifferentScale) {
auto column1 = std::make_shared<ColumnDecimal>(18, 2);
auto column2 = std::make_shared<ColumnDecimal>(18, 3);
column1->Append("1.23");
column2->Append("4.567");

EXPECT_THROW(column1->Swap(*column2), ValidationError);

EXPECT_EQ(column1->GetType().GetName(), "Decimal(18,2)");
EXPECT_EQ(column2->GetType().GetName(), "Decimal(18,3)");
EXPECT_EQ(column1->StringAt(0), "1.23");
EXPECT_EQ(column2->StringAt(0), "4.567");
}

TEST(ColumnsCase, DecimalSwapDifferentPrecision) {
auto column1 = std::make_shared<ColumnDecimal>(9, 2);
auto column2 = std::make_shared<ColumnDecimal>(18, 2);
column1->Append("1.23");
column2->Append("4.56");

EXPECT_THROW(column1->Swap(*column2), ValidationError);

EXPECT_EQ(column1->GetType().GetName(), "Decimal(9,2)");
EXPECT_EQ(column2->GetType().GetName(), "Decimal(18,2)");
EXPECT_EQ(column1->StringAt(0), "1.23");
EXPECT_EQ(column2->StringAt(0), "4.56");
}

TEST(ColumnsCase, DecimalSwapDifferentPrecisionSameStorageType) {
auto column1 = std::make_shared<ColumnDecimal>(17, 2);
auto column2 = std::make_shared<ColumnDecimal>(18, 2);
column1->Append("1.23");
column2->Append("4.56");

EXPECT_THROW(column1->Swap(*column2), ValidationError);

EXPECT_EQ(column1->GetType().GetName(), "Decimal(17,2)");
EXPECT_EQ(column2->GetType().GetName(), "Decimal(18,2)");
EXPECT_EQ(column1->StringAt(0), "1.23");
EXPECT_EQ(column2->StringAt(0), "4.56");
}

TEST(ColumnsCase, NumericInit) {
auto col = std::make_shared<ColumnUInt32>(MakeNumbers());

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