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68 lines
3.1 KiB
C++
68 lines
3.1 KiB
C++
#pragma once
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#include <DataTypes/IDataType.h>
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namespace DB
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{
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/// A nullable data type is an ordinary data type provided with a tag
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/// indicating that it also contains the NULL value. The following class
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/// embodies this concept.
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class DataTypeNullable final : public IDataType
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{
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public:
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static constexpr bool is_parametric = true;
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explicit DataTypeNullable(const DataTypePtr & nested_data_type_);
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std::string doGetName() const override { return "Nullable(" + nested_data_type->getName() + ")"; }
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const char * getFamilyName() const override { return "Nullable"; }
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TypeIndex getTypeId() const override { return TypeIndex::Nullable; }
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MutableColumnPtr createColumn() const override;
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Field getDefault() const override;
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bool equals(const IDataType & rhs) const override;
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bool isParametric() const override { return true; }
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bool haveSubtypes() const override { return true; }
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bool cannotBeStoredInTables() const override { return nested_data_type->cannotBeStoredInTables(); }
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bool shouldAlignRightInPrettyFormats() const override { return nested_data_type->shouldAlignRightInPrettyFormats(); }
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bool textCanContainOnlyValidUTF8() const override { return nested_data_type->textCanContainOnlyValidUTF8(); }
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bool isComparable() const override { return nested_data_type->isComparable(); }
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bool canBeComparedWithCollation() const override { return nested_data_type->canBeComparedWithCollation(); }
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bool canBeUsedAsVersion() const override { return false; }
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bool isSummable() const override { return nested_data_type->isSummable(); }
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bool canBeUsedInBooleanContext() const override { return nested_data_type->canBeUsedInBooleanContext() || onlyNull(); }
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bool haveMaximumSizeOfValue() const override { return nested_data_type->haveMaximumSizeOfValue(); }
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size_t getMaximumSizeOfValueInMemory() const override { return 1 + nested_data_type->getMaximumSizeOfValueInMemory(); }
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bool isNullable() const override { return true; }
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size_t getSizeOfValueInMemory() const override;
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bool onlyNull() const override;
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bool canBeInsideLowCardinality() const override { return nested_data_type->canBeInsideLowCardinality(); }
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bool canBePromoted() const override { return nested_data_type->canBePromoted(); }
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ColumnPtr createColumnConst(size_t size, const Field & field) const override;
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const DataTypePtr & getNestedType() const { return nested_data_type; }
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void forEachChild(const ChildCallback & callback) const override;
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private:
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SerializationPtr doGetDefaultSerialization() const override;
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DataTypePtr nested_data_type;
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};
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DataTypePtr makeNullable(const DataTypePtr & type);
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DataTypePtr makeNullableSafe(const DataTypePtr & type);
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DataTypePtr removeNullable(const DataTypePtr & type);
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DataTypePtr makeNullableOrLowCardinalityNullable(const DataTypePtr & type);
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DataTypePtr makeNullableOrLowCardinalityNullableSafe(const DataTypePtr & type);
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/// Nullable(T) -> T, LowCardinality(Nullable(T)) -> T
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DataTypePtr removeNullableOrLowCardinalityNullable(const DataTypePtr & type);
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bool canContainNull(const IDataType & type);
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}
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