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37 lines
1.3 KiB
C++
37 lines
1.3 KiB
C++
#pragma once
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#include <DataTypes/IDataTypeDummy.h>
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namespace DB
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{
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/** Data type that cannot have any values.
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* Used to represent NULL of unknown type as Nullable(Nothing),
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* and possibly for empty array of unknown type as Array(Nothing).
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*/
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class DataTypeNothing final : public IDataTypeDummy
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{
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public:
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static constexpr bool is_parametric = false;
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const char * getFamilyName() const override { return "Nothing"; }
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TypeIndex getTypeId() const override { return TypeIndex::Nothing; }
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MutableColumnPtr createColumn() const override;
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/// These methods read and write zero bytes just to allow to figure out size of column.
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void serializeBinaryBulk(const IColumn & column, WriteBuffer & ostr, size_t offset, size_t limit) const override;
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void deserializeBinaryBulk(IColumn & column, ReadBuffer & istr, size_t limit, double avg_value_size_hint) const override;
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bool equals(const IDataType & rhs) const override;
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bool isParametric() const override { return false; }
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bool textCanContainOnlyValidUTF8() const override { return true; }
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bool haveMaximumSizeOfValue() const override { return true; }
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size_t getSizeOfValueInMemory() const override { return 0; }
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bool canBeInsideNullable() const override { return true; }
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};
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}
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