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85 lines
2.8 KiB
C++
85 lines
2.8 KiB
C++
#include <Functions/IFunction.h>
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#include <Functions/FunctionHelpers.h>
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#include <Functions/FunctionFactory.h>
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#include <DataTypes/DataTypeArray.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <Columns/ColumnArray.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int ILLEGAL_TYPE_OF_ARGUMENT;
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extern const int TOO_LARGE_ARRAY_SIZE;
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}
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/// Reasonable threshold.
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static constexpr size_t max_arrays_size_in_block = 1000000000;
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/* arrayWithConstant(num, const) - make array of constants with length num.
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* arrayWithConstant(3, 'hello') = ['hello', 'hello', 'hello']
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* arrayWithConstant(1, 'hello') = ['hello']
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* arrayWithConstant(0, 'hello') = []
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*/
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class FunctionArrayWithConstant : public IFunction
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{
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public:
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static constexpr auto name = "arrayWithConstant";
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static FunctionPtr create(const Context &) { return std::make_shared<FunctionArrayWithConstant>(); }
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String getName() const override { return name; }
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size_t getNumberOfArguments() const override { return 2; }
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DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
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{
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if (!isNativeNumber(arguments[0]))
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throw Exception("Illegal type " + arguments[0]->getName() +
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" of argument of function " + getName() +
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", expected Integer", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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return std::make_shared<DataTypeArray>(arguments[1]);
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}
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bool useDefaultImplementationForConstants() const override { return true; }
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bool useDefaultImplementationForNulls() const override { return false; }
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void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t num_rows) override
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{
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const auto * col_num = block.getByPosition(arguments[0]).column.get();
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const auto * col_value = block.getByPosition(arguments[1]).column.get();
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auto offsets_col = ColumnArray::ColumnOffsets::create();
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ColumnArray::Offsets & offsets = offsets_col->getData();
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offsets.reserve(num_rows);
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ColumnArray::Offset offset = 0;
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for (size_t i = 0; i < num_rows; ++i)
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{
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auto array_size = col_num->getInt(i);
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if (unlikely(array_size < 0))
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throw Exception("Array size cannot be negative: while executing function " + getName(), ErrorCodes::TOO_LARGE_ARRAY_SIZE);
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offset += array_size;
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if (unlikely(offset > max_arrays_size_in_block))
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throw Exception("Too large array size while executing function " + getName(), ErrorCodes::TOO_LARGE_ARRAY_SIZE);
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offsets.push_back(offset);
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}
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block.getByPosition(result).column = ColumnArray::create(col_value->replicate(offsets), std::move(offsets_col));
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}
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};
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void registerFunctionArrayWithConstant(FunctionFactory & factory)
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{
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factory.registerFunction<FunctionArrayWithConstant>();
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}
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}
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