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64 lines
2.2 KiB
C++
64 lines
2.2 KiB
C++
#include <Functions/IFunction.h>
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#include <Functions/FunctionFactory.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <DataTypes/DataTypeLowCardinality.h>
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#include <Columns/ColumnsNumber.h>
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#include <Columns/ColumnLowCardinality.h>
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#include <Common/typeid_cast.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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}
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class FunctionLowCardinalityIndices: public IFunction
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{
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public:
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static constexpr auto name = "lowCardinalityIndices";
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static FunctionPtr create(const Context &) { return std::make_shared<FunctionLowCardinalityIndices>(); }
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String getName() const override { return name; }
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size_t getNumberOfArguments() const override { return 1; }
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bool useDefaultImplementationForNulls() const override { return false; }
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bool useDefaultImplementationForConstants() const override { return true; }
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bool useDefaultImplementationForLowCardinalityColumns() const override { return false; }
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DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
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{
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auto * type = typeid_cast<const DataTypeLowCardinality *>(arguments[0].get());
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if (!type)
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throw Exception("First first argument of function lowCardinalityIndexes must be ColumnLowCardinality, but got"
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+ arguments[0]->getName(), ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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return std::make_shared<DataTypeUInt64>();
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}
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void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) override
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{
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auto arg_num = arguments[0];
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const auto & arg = block.getByPosition(arg_num);
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auto & res = block.getByPosition(result);
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auto indexes_col = typeid_cast<const ColumnLowCardinality *>(arg.column.get())->getIndexesPtr();
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auto new_indexes_col = ColumnUInt64::create(indexes_col->size());
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auto & data = new_indexes_col->getData();
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for (size_t i = 0; i < data.size(); ++i)
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data[i] = indexes_col->getUInt(i);
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res.column = std::move(new_indexes_col);
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}
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};
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void registerFunctionLowCardinalityIndices(FunctionFactory & factory)
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{
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factory.registerFunction<FunctionLowCardinalityIndices>();
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}
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}
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