Method getDynamicSubcolumnData

src/DataTypes/DataTypeNullable.cpp:112–132

std::unique_ptr<ISerialization::SubstreamData> DataTypeNullable::getDynamicSubcolumnData(std::string_view subcolumn_name, const SubstreamData & data, size_t initial_array_level, bool throw_if_null) const
{
    auto nested_type = assert_cast<const DataTypeNullable &>(*data.type).nested_data_type;
    const auto & nullable_serialization = assert_cast<const SerializationNullable &>(*removeNamedSerialization(data.serialization));
    ISerialization::SubstreamData nested_data(nullable_serialization.getNested());
    nested_data.type = nested_type;
    nested_data.column = data.column ? assert_cast<const ColumnNullable &>(*data.column).getNestedColumnPtr() : nullptr;

    auto nested_subcolumn_data = DB::IDataType::getSubcolumnData(subcolumn_name, nested_data, initial_array_level, throw_if_null);
    if (!nested_subcolumn_data)
        return nullptr;

    auto creator = NullableSubcolumnCreator(data.column ? assert_cast<const ColumnNullable &>(*data.column).getNullMapColumnPtr() : nullptr);
    auto res = std::make_unique<ISerialization::SubstreamData>();
    res->serialization = creator.create(nested_subcolumn_data->serialization, nested_subcolumn_data->type);
    res->type = creator.create(nested_subcolumn_data->type);
    if (data.column)
        res->column = creator.create(nested_subcolumn_data->column);

    return res;
}

static DataTypePtr create(const ASTPtr & arguments)
{