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255 lines
7.9 KiB
C++
255 lines
7.9 KiB
C++
#include <DB/DataTypes/DataTypeNullable.h>
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#include <DB/DataTypes/NullSymbol.h>
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#include <DB/Columns/ColumnNullable.h>
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#include <DB/IO/ReadBuffer.h>
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#include <DB/IO/ReadHelpers.h>
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#include <DB/IO/WriteBuffer.h>
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#include <DB/IO/WriteHelpers.h>
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namespace DB
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{
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namespace
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{
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/// When a column is serialized as a binary data file, its null values are directly
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/// represented as null symbols into this file. The methods below are helpers that
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/// we use for the binary deserialization. They are used as follows:
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///
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/// auto action = NullDeserializer<NullSymbol::XXX>::execute(col, istr);
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///
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/// if (action == Action::NONE) /// eof
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/// return;
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/// else if (action == Action::ADD_ORDINARY) /// add an ordinary value
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/// ... deserialize the nested column ...
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///
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/// updateNullMap(col, action);
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///
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/// This two-step process is required because when we perform an INSERT query
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/// whose values are expressions, ValuesRowInputStream attempts to deserialize
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/// a stream, then raises an exception, and finally evaluates expressions inside
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/// the exception handler. If we did something like:
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///
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/// ... deserialize the null map...
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/// ... deserialize the nested column...
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///
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/// there would be garbage in the null map.
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/// Action to be performed while updating the null map of a nullable column.
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enum class Action
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{
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NONE, /// do nothing
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ADD_NULL, /// add a value indicating a NULL
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ADD_ORDINARY /// add a value indicating an ordinary value
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};
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/// The template class below provides one method that takes a nullable column being
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/// deserialized and looks if there is a pending null symbol in the corresponding
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/// binary data file. It returns the appropriate action to be performed on the null
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/// map of the column.
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template <typename Null>
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struct NullDeserializer
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{
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static Action execute(ColumnNullable & col, ReadBuffer & istr)
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{
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if (!istr.eof())
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{
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if (*istr.position() == Null::name[0])
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{
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++istr.position();
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static constexpr auto length = __builtin_strlen(Null::name);
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if (length > 1)
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assertString(&Null::name[1], istr);
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return Action::ADD_NULL;
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}
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else
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return Action::ADD_ORDINARY;
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}
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else
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return Action::NONE;
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}
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};
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/// This function takes the appropiate action when updating the null map of a nullable
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/// column.
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void updateNullMap(ColumnNullable & col, const Action & action)
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{
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auto & null_map = static_cast<ColumnUInt8 &>(*col.getNullValuesByteMap()).getData();
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if (action == Action::ADD_NULL)
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{
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null_map.push_back(1);
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ColumnPtr & nested_col = col.getNestedColumn();
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nested_col->insertDefault();
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}
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else if (action == Action::ADD_ORDINARY)
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null_map.push_back(0);
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else
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throw Exception{"DataTypeNullable: internal error", ErrorCodes::LOGICAL_ERROR};
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}
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}
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DataTypeNullable::DataTypeNullable(DataTypePtr nested_data_type_)
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: nested_data_type{nested_data_type_}
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{
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}
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void DataTypeNullable::serializeBinary(const IColumn & column, WriteBuffer & ostr, size_t offset, size_t limit) const
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{
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const ColumnNullable & col = static_cast<const ColumnNullable &>(column);
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nested_data_type->serializeBinary(*col.getNestedColumn(), ostr, offset, limit);
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}
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void DataTypeNullable::deserializeBinary(IColumn & column, ReadBuffer & istr, size_t limit, double avg_value_size_hint) const
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{
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ColumnNullable & col = static_cast<ColumnNullable &>(column);
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nested_data_type->deserializeBinary(*col.getNestedColumn(), istr, limit, avg_value_size_hint);
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}
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void DataTypeNullable::serializeBinary(const IColumn & column, size_t row_num, WriteBuffer & ostr) const
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{
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const ColumnNullable & col = static_cast<const ColumnNullable &>(column);
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nested_data_type->serializeBinary(*col.getNestedColumn(), row_num, ostr);
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}
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void DataTypeNullable::deserializeBinary(IColumn & column, ReadBuffer & istr) const
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{
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ColumnNullable & col = static_cast<ColumnNullable &>(column);
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nested_data_type->deserializeBinary(*col.getNestedColumn(), istr);
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}
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void DataTypeNullable::serializeTextEscaped(const IColumn & column, size_t row_num, WriteBuffer & ostr) const
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{
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const ColumnNullable & col = static_cast<const ColumnNullable &>(column);
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if (col.isNullAt(row_num))
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writeCString(NullSymbol::Escaped::name, ostr);
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else
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nested_data_type->serializeTextEscaped(*col.getNestedColumn(), row_num, ostr);
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}
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void DataTypeNullable::deserializeTextEscaped(IColumn & column, ReadBuffer & istr) const
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{
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ColumnNullable & col = static_cast<ColumnNullable &>(column);
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auto action = NullDeserializer<NullSymbol::Escaped>::execute(col, istr);
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if (action == Action::NONE)
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return;
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else if (action == Action::ADD_ORDINARY)
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nested_data_type->deserializeTextEscaped(*col.getNestedColumn(), istr);
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updateNullMap(col, action);
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}
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void DataTypeNullable::serializeTextQuoted(const IColumn & column, size_t row_num, WriteBuffer & ostr) const
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{
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const ColumnNullable & col = static_cast<const ColumnNullable &>(column);
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if (col.isNullAt(row_num))
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writeCString(NullSymbol::Quoted::name, ostr);
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else
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nested_data_type->serializeTextQuoted(*col.getNestedColumn(), row_num, ostr);
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}
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void DataTypeNullable::deserializeTextQuoted(IColumn & column, ReadBuffer & istr) const
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{
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ColumnNullable & col = static_cast<ColumnNullable &>(column);
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auto action = NullDeserializer<NullSymbol::Quoted>::execute(col, istr);
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if (action == Action::NONE)
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return;
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else if (action == Action::ADD_ORDINARY)
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nested_data_type->deserializeTextQuoted(*col.getNestedColumn(), istr);
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updateNullMap(col, action);
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}
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void DataTypeNullable::serializeTextCSV(const IColumn & column, size_t row_num, WriteBuffer & ostr) const
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{
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const ColumnNullable & col = static_cast<const ColumnNullable &>(column);
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if (col.isNullAt(row_num))
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writeCString(NullSymbol::Quoted::name, ostr);
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else
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nested_data_type->serializeTextCSV(*col.getNestedColumn(), row_num, ostr);
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}
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void DataTypeNullable::deserializeTextCSV(IColumn & column, ReadBuffer & istr, const char delimiter) const
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{
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ColumnNullable & col = static_cast<ColumnNullable &>(column);
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auto action = NullDeserializer<NullSymbol::Quoted>::execute(col, istr);
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if (action == Action::NONE)
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return;
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else if (action == Action::ADD_ORDINARY)
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nested_data_type->deserializeTextCSV(*col.getNestedColumn(), istr, delimiter);
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updateNullMap(col, action);
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}
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void DataTypeNullable::serializeText(const IColumn & column, size_t row_num, WriteBuffer & ostr) const
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{
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const ColumnNullable & col = static_cast<const ColumnNullable &>(column);
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if (col.isNullAt(row_num))
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writeCString(NullSymbol::Plain::name, ostr);
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else
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nested_data_type->serializeText(*col.getNestedColumn(), row_num, ostr);
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}
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void DataTypeNullable::serializeTextJSON(const IColumn & column, size_t row_num, WriteBuffer & ostr) const
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{
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const ColumnNullable & col = static_cast<const ColumnNullable &>(column);
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if (col.isNullAt(row_num))
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writeCString(NullSymbol::JSON::name, ostr);
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else
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nested_data_type->serializeTextJSON(*col.getNestedColumn(), row_num, ostr);
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}
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void DataTypeNullable::deserializeTextJSON(IColumn & column, ReadBuffer & istr) const
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{
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ColumnNullable & col = static_cast<ColumnNullable &>(column);
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auto action = NullDeserializer<NullSymbol::JSON>::execute(col, istr);
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if (action == Action::NONE)
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return;
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else if (action == Action::ADD_ORDINARY)
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nested_data_type->deserializeTextJSON(*col.getNestedColumn(), istr);
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updateNullMap(col, action);
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}
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void DataTypeNullable::serializeTextXML(const IColumn & column, size_t row_num, WriteBuffer & ostr) const
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{
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const ColumnNullable & col = static_cast<const ColumnNullable &>(column);
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if (col.isNullAt(row_num))
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writeCString(NullSymbol::XML::name, ostr);
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else
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nested_data_type->serializeTextXML(*col.getNestedColumn(), row_num, ostr);
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}
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ColumnPtr DataTypeNullable::createColumn() const
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{
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ColumnPtr new_col = nested_data_type->createColumn();
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return std::make_shared<ColumnNullable>(new_col, std::make_shared<ColumnUInt8>());
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}
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ColumnPtr DataTypeNullable::createConstColumn(size_t size, const Field & field) const
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{
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ColumnPtr new_col = nested_data_type->createConstColumn(size, field);
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return std::make_shared<ColumnNullable>(new_col, std::make_shared<ColumnUInt8>(size));
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}
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}
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