ClickHouse/dbms/src/Functions/FunctionsArray.cpp

#include <DB/Functions/FunctionFactory.h>
#include <DB/Functions/FunctionsArray.h>

namespace DB
{

void registerFunctionsArray(FunctionFactory & factory)
{
	factory.registerFunction<FunctionArray>();
	factory.registerFunction<FunctionArrayElement>();
	factory.registerFunction<FunctionHas>();
	factory.registerFunction<FunctionIndexOf>();
	factory.registerFunction<FunctionCountEqual>();
	factory.registerFunction<FunctionArrayEnumerate>();
	factory.registerFunction<FunctionArrayEnumerateUniq>();
	factory.registerFunction<FunctionArrayUniq>();
	factory.registerFunction<FunctionEmptyArrayUInt8>();
	factory.registerFunction<FunctionEmptyArrayUInt16>();
	factory.registerFunction<FunctionEmptyArrayUInt32>();
	factory.registerFunction<FunctionEmptyArrayUInt64>();
	factory.registerFunction<FunctionEmptyArrayInt8>();
	factory.registerFunction<FunctionEmptyArrayInt16>();
	factory.registerFunction<FunctionEmptyArrayInt32>();
	factory.registerFunction<FunctionEmptyArrayInt64>();
	factory.registerFunction<FunctionEmptyArrayFloat32>();
	factory.registerFunction<FunctionEmptyArrayFloat64>();
	factory.registerFunction<FunctionEmptyArrayDate>();
	factory.registerFunction<FunctionEmptyArrayDateTime>();
	factory.registerFunction<FunctionEmptyArrayString>();
	factory.registerFunction<FunctionEmptyArrayToSingle>();
	factory.registerFunction<FunctionRange>();
	factory.registerFunction<FunctionArrayReduce>();
}

/// Implementation of FunctionArray.

FunctionPtr FunctionArray::create(const Context & context)
{
	return std::make_shared<FunctionArray>(context);
}

FunctionArray::FunctionArray(const Context & context)
	: context(context)
{
}

String FunctionArray::getName() const
{
	return is_case_mode ? "CASE" : name;
}

namespace
{

/// Is there at least one numeric argument among the specified ones?
bool foundNumericType(const DataTypes & args)
{
	for (size_t i = 0; i < args.size(); ++i)
	{
		if (args[i]->behavesAsNumber())
			return true;
		else if (!args[i]->isNull())
			return false;
	}

	return false;
}

/// Is there at least one numeric column among the columns of the specified block?
bool foundNumericTypeInBlock(const Block & block)
{
	for (size_t i = 0; i < block.columns(); ++i)
	{
		const auto & type = block.unsafeGetByPosition(i).type;
		if (type->behavesAsNumber())
			return true;
		else if (!type->isNull())
			return false;
	}

	return false;
}

/// Do the specified arguments have the same type up to nullity?
bool hasArrayIdenticalTypes(const DataTypes & args)
{
	std::string first_type_name;

	for (size_t i = 0; i < args.size(); ++i)
	{
		if (!args[i]->isNull())
		{
			const IDataType * observed_type = DataTypeTraits::removeNullable(args[i]).get();
			const std::string & name = observed_type->getName();

			if (first_type_name.empty())
				first_type_name = name;
			else if (name != first_type_name)
				return false;
		}
	}

	return true;
}

template <typename T0, typename T1>
bool tryAddField(DataTypePtr type_res, const Field & f, Array & arr)
{
	if (typeid_cast<const T0 *>(type_res.get()))
	{
		if (f.isNull())
			arr.emplace_back();
		else
			arr.push_back(apply_visitor(FieldVisitorConvertToNumber<typename T1::FieldType>(), f));
		return true;
	}
	return false;
}

}

bool FunctionArray::addField(DataTypePtr type_res, const Field & f, Array & arr) const
{
	/// Иначе необходимо
	if (	tryAddField<DataTypeUInt8, DataTypeUInt64>(type_res, f, arr)
		||	tryAddField<DataTypeUInt16, DataTypeUInt64>(type_res, f, arr)
		||	tryAddField<DataTypeUInt32, DataTypeUInt64>(type_res, f, arr)
		||	tryAddField<DataTypeUInt64, DataTypeUInt64>(type_res, f, arr)
		||	tryAddField<DataTypeInt8, DataTypeInt64>(type_res, f, arr)
		||	tryAddField<DataTypeInt16, DataTypeInt64>(type_res, f, arr)
		||	tryAddField<DataTypeInt32, DataTypeInt64>(type_res, f, arr)
		||	tryAddField<DataTypeInt64, DataTypeInt64>(type_res, f, arr)
		||	tryAddField<DataTypeFloat32, DataTypeFloat64>(type_res, f, arr)
		||	tryAddField<DataTypeFloat64, DataTypeFloat64>(type_res, f, arr) )
		return true;
	else
	{
		if (is_case_mode)
			throw Exception{"Illegal type encountered while processing the CASE construction.",
				ErrorCodes::LOGICAL_ERROR};
		else
			throw Exception{"Illegal result type " + type_res->getName() + " of function " + getName(),
							ErrorCodes::LOGICAL_ERROR};
	}
}

const DataTypePtr & FunctionArray::getScalarType(const DataTypePtr & type)
{
	const auto array = typeid_cast<const DataTypeArray *>(type.get());

	if (!array)
		return type;

	return getScalarType(array->getNestedType());
}

DataTypeTraits::EnrichedDataTypePtr FunctionArray::getLeastCommonType(const DataTypes & arguments) const
{
	DataTypeTraits::EnrichedDataTypePtr result_type;

	try
	{
		result_type = Conditional::getArrayType(arguments);
	}
	catch (const Conditional::CondException & ex)
	{
		/// Translate a context-free error into a contextual error.
		if (is_case_mode)
		{
			if (ex.getCode() == Conditional::CondErrorCodes::TYPE_DEDUCER_ILLEGAL_COLUMN_TYPE)
				throw Exception{"Illegal type of column " + ex.getMsg1() +
					" in CASE construction", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT};
			else if (ex.getCode() == Conditional::CondErrorCodes::TYPE_DEDUCER_UPSCALING_ERROR)
				throw Exception{"THEN/ELSE clause parameters in CASE construction are not upscalable to a "
					"common type without loss of precision: " + ex.getMsg1(),
					ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT};
			else
				throw Exception{"An unexpected error has occurred in CASE expression",
					ErrorCodes::LOGICAL_ERROR};
		}
		else
		{
			if (ex.getCode() == Conditional::CondErrorCodes::TYPE_DEDUCER_ILLEGAL_COLUMN_TYPE)
				throw Exception{"Illegal type of column " + ex.getMsg1() +
					" in array", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT};
			else if (ex.getCode() == Conditional::CondErrorCodes::TYPE_DEDUCER_UPSCALING_ERROR)
				throw Exception("Arguments of function " + getName() + " are not upscalable "
					"to a common type without loss of precision.",
					ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
			else
				throw Exception{"An unexpected error has occurred in function " + getName(),
					ErrorCodes::LOGICAL_ERROR};
		}
	}

	return result_type;
}

void FunctionArray::setCaseMode()
{
	is_case_mode = true;
}

DataTypePtr FunctionArray::getReturnTypeImpl(const DataTypes & arguments) const
{
	if (arguments.empty())
	{
		if (is_case_mode)
			throw Exception{"Either WHEN clauses or THEN clauses are missing "
				"in the CASE construction.", ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH};
		else
			throw Exception{"Function array requires at least one argument.", ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH};
	}

	if (foundNumericType(arguments))
	{
		/// Since we have found at least one numeric argument, we infer that all
		/// the arguments are numeric up to nullity. Let's determine the least
		/// common type.
		auto enriched_result_type = getLeastCommonType(arguments);
		return std::make_shared<DataTypeArray>(enriched_result_type);
	}
	else
	{
		/// Otherwise all the arguments must have the same type.
		if (!hasArrayIdenticalTypes(arguments))
		{
			if (is_case_mode)
				throw Exception{"Found type discrepancy in either WHEN "
					"clauses or THEN clauses of the CASE construction",
					ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT};
			else
				throw Exception{"Arguments for function array must have same type or behave as number.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT};
		}

		return std::make_shared<DataTypeArray>(arguments[0]);
	}
}

void FunctionArray::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
	size_t num_elements = arguments.size();
	bool is_const = true;

	for (const auto arg_num : arguments)
	{
		if (!block.getByPosition(arg_num).column->isConst())
		{
			is_const = false;
			break;
		}
	}

	const auto first_arg = block.getByPosition(arguments[0]);
	DataTypePtr result_type = first_arg.type;
	DataTypeTraits::EnrichedDataTypePtr enriched_result_type;

	if (foundNumericTypeInBlock(block))
	{
		/// If type is numeric, calculate least common type.
		DataTypes types;
		types.reserve(num_elements);

		for (const auto & argument : arguments)
			types.push_back(block.getByPosition(argument).type);

		enriched_result_type = getLeastCommonType(types);
		result_type = enriched_result_type.first;
	}

	if (is_const)
	{
		const DataTypePtr & observed_type = DataTypeTraits::removeNullable(result_type);

		Array arr;
		for (const auto arg_num : arguments)
		{
			const auto & elem = block.getByPosition(arg_num);

			if (DataTypeTraits::removeNullable(elem.type)->getName() == observed_type->getName())
			{
				/// Если элемент такого же типа как результат, просто добавляем его в ответ
				arr.push_back((*elem.column)[0]);
			}
			else
			{
				/// Иначе необходимо привести его к типу результата
				addField(observed_type, (*elem.column)[0], arr);
			}
		}

		block.getByPosition(result).column = std::make_shared<ColumnConstArray>(
			first_arg.column->size(), arr, std::make_shared<DataTypeArray>(result_type));
	}
	else
	{
		size_t block_size = block.rowsInFirstColumn();

		/** If part of columns have not same type as common type of all elements of array,
		  *  then convert them to common type.
		  * If part of columns are constants,
		  *  then convert them to full columns.
		  */

		Columns columns_holder(num_elements);
		const IColumn * columns[num_elements];

		for (size_t i = 0; i < num_elements; ++i)
		{
			const auto & arg = block.getByPosition(arguments[i]);

			String result_type_name = result_type->getName();
			ColumnPtr preprocessed_column = arg.column;

			if (arg.type->getName() != result_type_name)
			{
				Block temporary_block
				{
					{
						arg.column,
						arg.type,
						arg.name
					},
					{
						std::make_shared<ColumnConstString>(block_size, result_type_name),
						std::make_shared<DataTypeString>(),
						""
					},
					{
						nullptr,
						result_type,
						""
					}
				};

				FunctionCast func_cast(context);

				{
					DataTypePtr unused_return_type;
					ColumnsWithTypeAndName arguments{ temporary_block.unsafeGetByPosition(0), temporary_block.unsafeGetByPosition(1) };
					std::vector<ExpressionAction> unused_prerequisites;

					/// Prepares function to execution. TODO It is not obvious.
					func_cast.getReturnTypeAndPrerequisites(arguments, unused_return_type, unused_prerequisites);
				}

				func_cast.execute(temporary_block, {0, 1}, 2);
				preprocessed_column = temporary_block.unsafeGetByPosition(2).column;
			}

			if (auto materialized_column = preprocessed_column->convertToFullColumnIfConst())
				preprocessed_column = materialized_column;

			columns_holder[i] = std::move(preprocessed_column);
			columns[i] = columns_holder[i].get();
		}

		/** Create and fill the result array.
		  */

		auto out = std::make_shared<ColumnArray>(result_type->createColumn());
		IColumn & out_data = out->getData();
		IColumn::Offsets_t & out_offsets = out->getOffsets();

		out_data.reserve(block_size * num_elements);
		out_offsets.resize(block_size);

		IColumn::Offset_t current_offset = 0;
		for (size_t i = 0; i < block_size; ++i)
		{
			for (size_t j = 0; j < num_elements; ++j)
				out_data.insertFrom(*columns[j], i);

			current_offset += num_elements;
			out_offsets[i] = current_offset;
		}

		block.getByPosition(result).column = out;
	}
}

/// Implementation of FunctionArrayElement.

namespace ArrayImpl
{

class NullMapBuilder
{
public:
	operator bool() const { return (src_nullable_col != nullptr) || (src_array != nullptr); }
	bool operator!() const { return (src_nullable_col == nullptr) && (src_array == nullptr); }

	void initSource(const ColumnNullable & src_nullable_col_)
	{
		src_nullable_col = &src_nullable_col_;
	}

	void initSource(const Array & src_array_)
	{
		src_array = &src_array_;
	}

	void initSink(size_t s)
	{
		sink_null_map = std::make_shared<ColumnUInt8>(s);
		size = s;
	}

	void update(size_t from)
	{
		if (index >= size)
			throw Exception{"Internal errror", ErrorCodes::LOGICAL_ERROR};

		bool is_null;
		if (src_nullable_col != nullptr)
			is_null = src_nullable_col->isNullAt(from);
		else
			is_null = (*src_array)[from].isNull();

		auto & null_map_data = static_cast<ColumnUInt8 &>(*sink_null_map).getData();
		null_map_data[index] = is_null ? 1 : 0;

		++index;
	}

	void update()
	{
		if (index >= size)
			throw Exception{"Internal errror", ErrorCodes::LOGICAL_ERROR};

		auto & null_map_data = static_cast<ColumnUInt8 &>(*sink_null_map).getData();
		null_map_data[index] = 0;
		++index;
	}

	ColumnPtr getNullMap() const { return sink_null_map; }

private:
	const ColumnNullable * src_nullable_col = nullptr;
	const Array * src_array = nullptr;
	ColumnPtr sink_null_map;
	size_t size = 0;
	size_t index = 0;
};

}

namespace
{

template <typename T>
struct ArrayElementNumImpl
{
	/** Implementation for constant index.
	  * If negative = false - index is from beginning of array, started from 1.
	  * If negative = true - index is from end of array, started from -1.
	  */
	template <bool negative>
	static void vectorConst(
		const PaddedPODArray<T> & data, const ColumnArray::Offsets_t & offsets,
		const ColumnArray::Offset_t index,
		PaddedPODArray<T> & result, ArrayImpl::NullMapBuilder & builder)
	{
		size_t size = offsets.size();
		result.resize(size);

		ColumnArray::Offset_t current_offset = 0;
		for (size_t i = 0; i < size; ++i)
		{
			size_t array_size = offsets[i] - current_offset;

			if (index < array_size)
			{
				size_t j = !negative ? (current_offset + index) : (offsets[i] - index - 1);
				result[i] = data[j];
				if (builder)
					builder.update(j);
			}
			else
			{
				result[i] = T();

				if (builder)
					builder.update();
			}

			current_offset = offsets[i];
		}
	}

	/** Implementation for non-constant index.
	  */
	template <typename TIndex>
	static void vector(
		const PaddedPODArray<T> & data, const ColumnArray::Offsets_t & offsets,
		const PaddedPODArray<TIndex> & indices,
		PaddedPODArray<T> & result, ArrayImpl::NullMapBuilder & builder)
	{
		size_t size = offsets.size();
		result.resize(size);

		ColumnArray::Offset_t current_offset = 0;
		for (size_t i = 0; i < size; ++i)
		{
			size_t array_size = offsets[i] - current_offset;

			TIndex index = indices[i];
			if (index > 0 && static_cast<size_t>(index) <= array_size)
			{
				size_t j = current_offset + index - 1;
				result[i] = data[j];

				if (builder)
					builder.update(j);
			}
			else if (index < 0 && static_cast<size_t>(-index) <= array_size)
			{
				size_t j = offsets[i] + index;
				result[i] = data[j];

				if (builder)
					builder.update(j);
			}
			else
			{
				result[i] = T();

				if (builder)
					builder.update();
			}

			current_offset = offsets[i];
		}
	}
};

struct ArrayElementStringImpl
{
	/** Implementation for constant index.
	  * If negative = false - index is from beginning of array, started from 1.
	  * If negative = true - index is from end of array, started from -1.
	  */
	template <bool negative>
	static void vectorConst(
		const ColumnString::Chars_t & data, const ColumnArray::Offsets_t & offsets, const ColumnString::Offsets_t & string_offsets,
		const ColumnArray::Offset_t index,
		ColumnString::Chars_t & result_data, ColumnArray::Offsets_t & result_offsets,
		ArrayImpl::NullMapBuilder & builder)
	{
		size_t size = offsets.size();
		result_offsets.resize(size);
		result_data.reserve(data.size());

		ColumnArray::Offset_t current_offset = 0;
		ColumnArray::Offset_t current_result_offset = 0;
		for (size_t i = 0; i < size; ++i)
		{
			size_t array_size = offsets[i] - current_offset;

			if (index < array_size)
			{
				size_t adjusted_index = !negative ? index : (array_size - index - 1);

				size_t j =  (current_offset == 0 && adjusted_index == 0) ? 0 : current_offset + adjusted_index;
				if (builder)
					builder.update(j);

				ColumnArray::Offset_t string_pos = current_offset == 0 && adjusted_index == 0
					? 0
					: string_offsets[current_offset + adjusted_index - 1];

				ColumnArray::Offset_t string_size = string_offsets[current_offset + adjusted_index] - string_pos;

				result_data.resize(current_result_offset + string_size);
				memcpySmallAllowReadWriteOverflow15(&result_data[current_result_offset], &data[string_pos], string_size);
				current_result_offset += string_size;
				result_offsets[i] = current_result_offset;
			}
			else
			{
				/// Вставим пустую строку.
				result_data.resize(current_result_offset + 1);
				result_data[current_result_offset] = 0;
				current_result_offset += 1;
				result_offsets[i] = current_result_offset;

				if (builder)
					builder.update();
			}

			current_offset = offsets[i];
		}
	}

	/** Implementation for non-constant index.
	  */
	template <typename TIndex>
	static void vector(
		const ColumnString::Chars_t & data, const ColumnArray::Offsets_t & offsets, const ColumnString::Offsets_t & string_offsets,
		const PaddedPODArray<TIndex> & indices,
		ColumnString::Chars_t & result_data, ColumnArray::Offsets_t & result_offsets,
		ArrayImpl::NullMapBuilder & builder)
	{
		size_t size = offsets.size();
		result_offsets.resize(size);
		result_data.reserve(data.size());

		ColumnArray::Offset_t current_offset = 0;
		ColumnArray::Offset_t current_result_offset = 0;
		for (size_t i = 0; i < size; ++i)
		{
			size_t array_size = offsets[i] - current_offset;
			size_t adjusted_index;	/// index in array from zero

			TIndex index = indices[i];
			if (index > 0 && static_cast<size_t>(index) <= array_size)
				adjusted_index = index - 1;
			else if (index < 0 && static_cast<size_t>(-index) <= array_size)
				adjusted_index = array_size + index;
			else
				adjusted_index = array_size;	/// means no element should be taken

			if (adjusted_index < array_size)
			{
				size_t j = (current_offset == 0 && adjusted_index == 0) ? 0 : current_offset + adjusted_index - 1;
				if (builder)
					builder.update(j);

				ColumnArray::Offset_t string_pos = current_offset == 0 && adjusted_index == 0
					? 0
					: string_offsets[current_offset + adjusted_index - 1];

				ColumnArray::Offset_t string_size = string_offsets[current_offset + adjusted_index] - string_pos;

				result_data.resize(current_result_offset + string_size);
				memcpySmallAllowReadWriteOverflow15(&result_data[current_result_offset], &data[string_pos], string_size);
				current_result_offset += string_size;
				result_offsets[i] = current_result_offset;
			}
			else
			{
				/// Insert empty string
				result_data.resize(current_result_offset + 1);
				result_data[current_result_offset] = 0;
				current_result_offset += 1;
				result_offsets[i] = current_result_offset;

				if (builder)
					builder.update();
			}

			current_offset = offsets[i];
		}
	}
};

/// Generic implementation for other nested types.
struct ArrayElementGenericImpl
{
	/** Implementation for constant index.
	  * If negative = false - index is from beginning of array, started from 1.
	  * If negative = true - index is from end of array, started from -1.
	  */
	template <bool negative>
	static void vectorConst(
		const IColumn & data, const ColumnArray::Offsets_t & offsets,
		const ColumnArray::Offset_t index,
		IColumn & result, ArrayImpl::NullMapBuilder & builder)
	{
		size_t size = offsets.size();
		result.reserve(size);

		ColumnArray::Offset_t current_offset = 0;
		for (size_t i = 0; i < size; ++i)
		{
			size_t array_size = offsets[i] - current_offset;

			if (index < array_size)
			{
				size_t j = !negative ? current_offset + index : offsets[i] - index - 1;
				result.insertFrom(data, j);
				if (builder)
					builder.update(j);
			}
			else
			{
				result.insertDefault();
				if (builder)
					builder.update();
			}

			current_offset = offsets[i];
		}
	}

	/** Implementation for non-constant index.
	  */
	template <typename TIndex>
	static void vector(
		const IColumn & data, const ColumnArray::Offsets_t & offsets,
		const PaddedPODArray<TIndex> & indices,
		IColumn & result, ArrayImpl::NullMapBuilder & builder)
	{
		size_t size = offsets.size();
		result.reserve(size);

		ColumnArray::Offset_t current_offset = 0;
		for (size_t i = 0; i < size; ++i)
		{
			size_t array_size = offsets[i] - current_offset;

			TIndex index = indices[i];
			if (index > 0 && static_cast<size_t>(index) <= array_size)
			{
				size_t j = current_offset + index - 1;
				result.insertFrom(data, j);
				if (builder)
					builder.update(j);
			}
			else if (index < 0 && static_cast<size_t>(-index) <= array_size)
			{
				size_t j = offsets[i] + index;
				result.insertFrom(data, j);
				if (builder)
					builder.update(j);
			}
			else
			{
				result.insertDefault();
				if (builder)
					builder.update();
			}

			current_offset = offsets[i];
		}
	}
};

}


FunctionPtr FunctionArrayElement::create(const Context & context)
{
	return std::make_shared<FunctionArrayElement>();
}


template <typename DataType>
bool FunctionArrayElement::executeNumberConst(Block & block, const ColumnNumbers & arguments, size_t result, const Field & index,
	ArrayImpl::NullMapBuilder & builder)
{
	const ColumnArray * col_array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	const ColumnVector<DataType> * col_nested = typeid_cast<const ColumnVector<DataType> *>(&col_array->getData());

	if (!col_nested)
		return false;

	auto col_res = std::make_shared<ColumnVector<DataType>>();
	block.getByPosition(result).column = col_res;

	if (index.getType() == Field::Types::UInt64)
		ArrayElementNumImpl<DataType>::template vectorConst<false>(
			col_nested->getData(), col_array->getOffsets(), safeGet<UInt64>(index) - 1, col_res->getData(), builder);
	else if (index.getType() == Field::Types::Int64)
		ArrayElementNumImpl<DataType>::template vectorConst<true>(
			col_nested->getData(), col_array->getOffsets(), -safeGet<Int64>(index) - 1, col_res->getData(), builder);
	else
		throw Exception("Illegal type of array index", ErrorCodes::LOGICAL_ERROR);

	return true;
}

template <typename IndexType, typename DataType>
bool FunctionArrayElement::executeNumber(Block & block, const ColumnNumbers & arguments, size_t result, const PaddedPODArray<IndexType> & indices,
	ArrayImpl::NullMapBuilder & builder)
{
	const ColumnArray * col_array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	const ColumnVector<DataType> * col_nested = typeid_cast<const ColumnVector<DataType> *>(&col_array->getData());

	if (!col_nested)
		return false;

	auto col_res = std::make_shared<ColumnVector<DataType>>();
	block.getByPosition(result).column = col_res;

	ArrayElementNumImpl<DataType>::template vector<IndexType>(
		col_nested->getData(), col_array->getOffsets(), indices, col_res->getData(), builder);

	return true;
}

bool FunctionArrayElement::executeStringConst(Block & block, const ColumnNumbers & arguments, size_t result, const Field & index,
	ArrayImpl::NullMapBuilder & builder)
{
	const ColumnArray * col_array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	const ColumnString * col_nested = typeid_cast<const ColumnString *>(&col_array->getData());

	if (!col_nested)
		return false;

	std::shared_ptr<ColumnString> col_res = std::make_shared<ColumnString>();
	block.getByPosition(result).column = col_res;

	if (index.getType() == Field::Types::UInt64)
		ArrayElementStringImpl::vectorConst<false>(
			col_nested->getChars(),
			col_array->getOffsets(),
			col_nested->getOffsets(),
			safeGet<UInt64>(index) - 1,
			col_res->getChars(),
			col_res->getOffsets(),
			builder);
	else if (index.getType() == Field::Types::Int64)
		ArrayElementStringImpl::vectorConst<true>(
			col_nested->getChars(),
			col_array->getOffsets(),
			col_nested->getOffsets(),
			-safeGet<Int64>(index) - 1,
			col_res->getChars(),
			col_res->getOffsets(),
			builder);
	else
		throw Exception("Illegal type of array index", ErrorCodes::LOGICAL_ERROR);

	return true;
}

template <typename IndexType>
bool FunctionArrayElement::executeString(Block & block, const ColumnNumbers & arguments, size_t result, const PaddedPODArray<IndexType> & indices,
	ArrayImpl::NullMapBuilder & builder)
{
	const ColumnArray * col_array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	const ColumnString * col_nested = typeid_cast<const ColumnString *>(&col_array->getData());

	if (!col_nested)
		return false;

	std::shared_ptr<ColumnString> col_res = std::make_shared<ColumnString>();
	block.getByPosition(result).column = col_res;

	ArrayElementStringImpl::vector<IndexType>(
		col_nested->getChars(),
		col_array->getOffsets(),
		col_nested->getOffsets(),
		indices,
		col_res->getChars(),
		col_res->getOffsets(),
		builder);

	return true;
}

bool FunctionArrayElement::executeGenericConst(Block & block, const ColumnNumbers & arguments, size_t result, const Field & index,
	ArrayImpl::NullMapBuilder & builder)
{
	const ColumnArray * col_array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	const auto & col_nested = col_array->getData();
	auto col_res = col_nested.cloneEmpty();
	block.getByPosition(result).column = col_res;

	if (index.getType() == Field::Types::UInt64)
		ArrayElementGenericImpl::vectorConst<false>(
			col_nested, col_array->getOffsets(), safeGet<UInt64>(index) - 1, *col_res, builder);
	else if (index.getType() == Field::Types::Int64)
		ArrayElementGenericImpl::vectorConst<true>(
			col_nested, col_array->getOffsets(), -safeGet<Int64>(index) - 1, *col_res, builder);
	else
		throw Exception("Illegal type of array index", ErrorCodes::LOGICAL_ERROR);

	return true;
}

template <typename IndexType>
bool FunctionArrayElement::executeGeneric(Block & block, const ColumnNumbers & arguments, size_t result, const PaddedPODArray<IndexType> & indices,
	ArrayImpl::NullMapBuilder & builder)
{
	const ColumnArray * col_array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	const auto & col_nested = col_array->getData();
	auto col_res = col_nested.cloneEmpty();
	block.getByPosition(result).column = col_res;

	ArrayElementGenericImpl::vector<IndexType>(
		col_nested, col_array->getOffsets(), indices, *col_res, builder);

	return true;
}

bool FunctionArrayElement::executeConstConst(Block & block, const ColumnNumbers & arguments, size_t result, const Field & index,
	ArrayImpl::NullMapBuilder & builder)
{
	const ColumnConstArray * col_array = typeid_cast<const ColumnConstArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	const DB::Array & array = col_array->getData();
	size_t array_size = array.size();
	size_t real_index = 0;

	if (index.getType() == Field::Types::UInt64)
		real_index = safeGet<UInt64>(index) - 1;
	else if (index.getType() == Field::Types::Int64)
		real_index = array_size + safeGet<Int64>(index);
	else
		throw Exception("Illegal type of array index", ErrorCodes::LOGICAL_ERROR);

	Field value = col_array->getData().at(real_index);
	if (value.isNull())
		value = DataTypeString{}.getDefault();

	block.getByPosition(result).column = block.getByPosition(result).type->createConstColumn(
		block.rowsInFirstColumn(),
		value);

	if (builder)
		builder.update(real_index);

	return true;
}

template <typename IndexType>
bool FunctionArrayElement::executeConst(Block & block, const ColumnNumbers & arguments, size_t result, const PaddedPODArray<IndexType> & indices,
	ArrayImpl::NullMapBuilder & builder)
{
	const ColumnConstArray * col_array = typeid_cast<const ColumnConstArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	const DB::Array & array = col_array->getData();
	size_t array_size = array.size();

	block.getByPosition(result).column = block.getByPosition(result).type->createColumn();

	for (size_t i = 0; i < col_array->size(); ++i)
	{
		IndexType index = indices[i];
		if (index > 0 && static_cast<size_t>(index) <= array_size)
		{
			size_t j = index - 1;
			block.getByPosition(result).column->insert(array[j]);
			if (builder)
				builder.update(j);
		}
		else if (index < 0 && static_cast<size_t>(-index) <= array_size)
		{
			size_t j = array_size + index;
			block.getByPosition(result).column->insert(array[j]);
			if (builder)
				builder.update(j);
		}
		else
		{
			block.getByPosition(result).column->insertDefault();
			if (builder)
				builder.update();
		}
	}

	return true;
}

template <typename IndexType>
bool FunctionArrayElement::executeArgument(Block & block, const ColumnNumbers & arguments, size_t result,
	ArrayImpl::NullMapBuilder & builder)
{
	auto index = typeid_cast<const ColumnVector<IndexType> *>(block.getByPosition(arguments[1]).column.get());

	if (!index)
		return false;

	const auto & index_data = index->getData();

	if (builder)
		builder.initSink(index_data.size());

	if (!(	executeNumber<IndexType, UInt8>		(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, UInt16>	(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, UInt32>	(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, UInt64>	(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, Int8>		(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, Int16>		(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, Int32>		(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, Int64>		(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, Float32>	(block, arguments, result, index_data, builder)
		||	executeNumber<IndexType, Float64>	(block, arguments, result, index_data, builder)
		||	executeConst <IndexType>			(block, arguments, result, index_data, builder)
		||	executeString<IndexType>			(block, arguments, result, index_data, builder)
		||	executeGeneric<IndexType>			(block, arguments, result, index_data, builder)))
	throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName()
				+ " of first argument of function " + getName(), ErrorCodes::ILLEGAL_COLUMN);

	return true;
}

bool FunctionArrayElement::executeTuple(Block & block, const ColumnNumbers & arguments, size_t result)
{
	ColumnArray * col_array = typeid_cast<ColumnArray *>(block.getByPosition(arguments[0]).column.get());

	if (!col_array)
		return false;

	ColumnTuple * col_nested = typeid_cast<ColumnTuple *>(&col_array->getData());

	if (!col_nested)
		return false;

	Block & tuple_block = col_nested->getData();
	size_t tuple_size = tuple_block.columns();

	/** Будем вычислять функцию для кортежа внутренностей массива.
	  * Для этого создадим временный блок.
	  * Он будет состоять из следующих столбцов:
	  * - индекс массива, который нужно взять;
	  * - массив из первых элементов кортежей;
	  * - результат взятия элементов по индексу для массива из первых элементов кортежей;
	  * - массив из вторых элементов кортежей;
	  * - результат взятия элементов по индексу для массива из вторых элементов кортежей;
	  * ...
	  */
	Block block_of_temporary_results;
	block_of_temporary_results.insert(block.getByPosition(arguments[1]));

	/// результаты взятия элементов по индексу для массивов из каждых элементов кортежей;
	Block result_tuple_block;

	for (size_t i = 0; i < tuple_size; ++i)
	{
		ColumnWithTypeAndName array_of_tuple_section;
		array_of_tuple_section.column = std::make_shared<ColumnArray>(
			tuple_block.getByPosition(i).column, col_array->getOffsetsColumn());
		array_of_tuple_section.type = std::make_shared<DataTypeArray>(
			tuple_block.getByPosition(i).type);
		block_of_temporary_results.insert(array_of_tuple_section);

		ColumnWithTypeAndName array_elements_of_tuple_section;
		block_of_temporary_results.insert(array_elements_of_tuple_section);

		executeImpl(block_of_temporary_results, ColumnNumbers{i * 2 + 1, 0}, i * 2 + 2);

		result_tuple_block.insert(block_of_temporary_results.getByPosition(i * 2 + 2));
	}

	auto col_res = std::make_shared<ColumnTuple>(result_tuple_block);
	block.getByPosition(result).column = col_res;

	return true;
}

String FunctionArrayElement::getName() const
{
	return name;
}

DataTypePtr FunctionArrayElement::getReturnTypeImpl(const DataTypes & arguments) const
{
	if (arguments.size() != 2)
		throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
			+ toString(arguments.size()) + ", should be 2.",
			ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

	const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(arguments[0].get());
	if (!array_type)
		throw Exception("First argument for function " + getName() + " must be array.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

	if (!arguments[1]->isNumeric()
		|| (!startsWith(arguments[1]->getName(), "UInt") && !startsWith(arguments[1]->getName(), "Int")))
		throw Exception("Second argument for function " + getName() + " must have UInt or Int type.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

	return array_type->getNestedType();
}

/// Выполнить функцию над блоком.
void FunctionArrayElement::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
	/// Check nullability.
	bool is_nullable;

	const ColumnArray * col_array = nullptr;
	const ColumnConstArray * col_const_array = nullptr;

	col_array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());
	if (col_array)
		is_nullable = col_array->getData().isNullable();
	else
	{
		col_const_array = typeid_cast<const ColumnConstArray *>(block.getByPosition(arguments[0]).column.get());
		if (col_const_array)
		{
			const auto & arr = col_const_array->getData();
			is_nullable = std::any_of(arr.begin(), arr.end(), [](const Field & f){ return f.isNull(); });
		}
		else
			throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName()
			+ " of first argument of function " + getName(), ErrorCodes::ILLEGAL_COLUMN);
	}

	if (!is_nullable)
	{
		ArrayImpl::NullMapBuilder builder;
		perform(block, arguments, result, builder);
	}
	else
	{
		/// Perform initializations.
		ArrayImpl::NullMapBuilder builder;
		Block source_block;

		const auto & input_type = static_cast<const DataTypeNullable &>(*block.getByPosition(arguments[0]).type).getNestedType();
		const auto & tmp_ret_type = static_cast<const DataTypeNullable &>(*block.getByPosition(result).type).getNestedType();

		if (col_array)
		{
			const auto & nullable_col = static_cast<const ColumnNullable &>(col_array->getData());
			const auto & nested_col = nullable_col.getNestedColumn();

			/// Put nested_col inside a ColumnArray.
			source_block =
			{
				{
					std::make_shared<ColumnArray>(nested_col, col_array->getOffsetsColumn()),
					std::make_shared<DataTypeArray>(input_type),
					""
				},
				block.getByPosition(arguments[1]),
				{
					nullptr,
					tmp_ret_type,
					""
				}
			};

			builder.initSource(nullable_col);
		}
		else
		{
			/// Almost a copy of block.
			source_block =
			{
				block.getByPosition(arguments[0]),
				block.getByPosition(arguments[1]),
				{
					nullptr,
					tmp_ret_type,
					""
				}
			};

			builder.initSource(col_const_array->getData());
		}

		perform(source_block, {0, 1}, 2, builder);

		/// Store the result.
		const ColumnWithTypeAndName & source_col = source_block.unsafeGetByPosition(2);
		ColumnWithTypeAndName & dest_col = block.unsafeGetByPosition(result);
		dest_col.column = std::make_shared<ColumnNullable>(source_col.column, builder.getNullMap());
	}
}

void FunctionArrayElement::perform(Block & block, const ColumnNumbers & arguments, size_t result,
	ArrayImpl::NullMapBuilder & builder)
{
	if (executeTuple(block, arguments, result))
	{
	}
	else if (!block.getByPosition(arguments[1]).column->isConst())
	{
		if (!(	executeArgument<UInt8>	(block, arguments, result, builder)
			||	executeArgument<UInt16>	(block, arguments, result, builder)
			||	executeArgument<UInt32>	(block, arguments, result, builder)
			||	executeArgument<UInt64>	(block, arguments, result, builder)
			||	executeArgument<Int8>	(block, arguments, result, builder)
			||	executeArgument<Int16>	(block, arguments, result, builder)
			||	executeArgument<Int32>	(block, arguments, result, builder)
			||	executeArgument<Int64>	(block, arguments, result, builder)))
		throw Exception("Second argument for function " + getName() + " must must have UInt or Int type.",
						ErrorCodes::ILLEGAL_COLUMN);
	}
	else
	{
		Field index = (*block.getByPosition(arguments[1]).column)[0];

		if (builder)
			builder.initSink(block.rowsInFirstColumn());

		if (index == UInt64(0))
			throw Exception("Array indices is 1-based", ErrorCodes::ZERO_ARRAY_OR_TUPLE_INDEX);

		if (!(	executeNumberConst<UInt8>	(block, arguments, result, index, builder)
			||	executeNumberConst<UInt16>	(block, arguments, result, index, builder)
			||	executeNumberConst<UInt32>	(block, arguments, result, index, builder)
			||	executeNumberConst<UInt64>	(block, arguments, result, index, builder)
			||	executeNumberConst<Int8>	(block, arguments, result, index, builder)
			||	executeNumberConst<Int16>	(block, arguments, result, index, builder)
			||	executeNumberConst<Int32>	(block, arguments, result, index, builder)
			||	executeNumberConst<Int64>	(block, arguments, result, index, builder)
			||	executeNumberConst<Float32>	(block, arguments, result, index, builder)
			||	executeNumberConst<Float64>	(block, arguments, result, index, builder)
			||	executeConstConst			(block, arguments, result, index, builder)
			||	executeStringConst			(block, arguments, result, index, builder)
			||	executeGenericConst			(block, arguments, result, index, builder)))
		throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName()
			+ " of first argument of function " + getName(),
			ErrorCodes::ILLEGAL_COLUMN);
	}
}

/// Implementation of FunctionArrayEnumerate.

FunctionPtr FunctionArrayEnumerate::create(const Context & context)
{
	return std::make_shared<FunctionArrayEnumerate>();
}

String FunctionArrayEnumerate::getName() const
{
	return name;
}

DataTypePtr FunctionArrayEnumerate::getReturnTypeImpl(const DataTypes & arguments) const
{
	if (arguments.size() != 1)
		throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
			+ toString(arguments.size()) + ", should be 1.",
			ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

	const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(arguments[0].get());
	if (!array_type)
		throw Exception("First argument for function " + getName() + " must be array.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

	return std::make_shared<DataTypeArray>(std::make_shared<DataTypeUInt32>());
}

void FunctionArrayEnumerate::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
	if (const ColumnArray * array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get()))
	{
		const ColumnArray::Offsets_t & offsets = array->getOffsets();

		auto res_nested = std::make_shared<ColumnUInt32>();
		auto res_array = std::make_shared<ColumnArray>(res_nested, array->getOffsetsColumn());
		block.getByPosition(result).column = res_array;

		ColumnUInt32::Container_t & res_values = res_nested->getData();
		res_values.resize(array->getData().size());
		size_t prev_off = 0;
		for (size_t i = 0; i < offsets.size(); ++i)
		{
			size_t off = offsets[i];
			for (size_t j = prev_off; j < off; ++j)
			{
				res_values[j] = j - prev_off + 1;
			}
			prev_off = off;
		}
	}
	else if (const ColumnConstArray * array = typeid_cast<const ColumnConstArray *>(block.getByPosition(arguments[0]).column.get()))
	{
		const Array & values = array->getData();

		Array res_values(values.size());
		for (size_t i = 0; i < values.size(); ++i)
		{
			res_values[i] = i + 1;
		}

		auto res_array = std::make_shared<ColumnConstArray>(array->size(), res_values, std::make_shared<DataTypeArray>(std::make_shared<DataTypeUInt32>()));
		block.getByPosition(result).column = res_array;
	}
	else
	{
		throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName()
				+ " of first argument of function " + getName(),
			ErrorCodes::ILLEGAL_COLUMN);
	}
}

/// Implementation of FunctionArrayUniq.

FunctionPtr FunctionArrayUniq::create(const Context & context) { return std::make_shared<FunctionArrayUniq>(); }

String FunctionArrayUniq::getName() const
{
	return name;
}

DataTypePtr FunctionArrayUniq::getReturnTypeImpl(const DataTypes & arguments) const
{
	if (arguments.size() == 0)
		throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
			+ toString(arguments.size()) + ", should be at least 1.",
			ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

	for (size_t i = 0; i < arguments.size(); ++i)
	{
		const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(arguments[i].get());
		if (!array_type)
			throw Exception("All arguments for function " + getName() + " must be arrays; argument " + toString(i + 1) + " isn't.",
				ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
	}

	return std::make_shared<DataTypeUInt32>();
}

void FunctionArrayUniq::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
	if (arguments.size() == 1 && executeConst(block, arguments, result))
		return;

	Columns array_columns(arguments.size());
	const ColumnArray::Offsets_t * offsets = nullptr;
	ConstColumnPlainPtrs data_columns(arguments.size());

	for (size_t i = 0; i < arguments.size(); ++i)
	{
		ColumnPtr array_ptr = block.getByPosition(arguments[i]).column;
		const ColumnArray * array = typeid_cast<const ColumnArray *>(array_ptr.get());
		if (!array)
		{
			const ColumnConstArray * const_array = typeid_cast<const ColumnConstArray *>(
				block.getByPosition(arguments[i]).column.get());
			if (!const_array)
				throw Exception("Illegal column " + block.getByPosition(arguments[i]).column->getName()
					+ " of " + toString(i + 1) + "-th argument of function " + getName(),
					ErrorCodes::ILLEGAL_COLUMN);
			array_ptr = const_array->convertToFullColumn();
			array = typeid_cast<const ColumnArray *>(array_ptr.get());
		}
		array_columns[i] = array_ptr;
		const ColumnArray::Offsets_t & offsets_i = array->getOffsets();
		if (!i)
			offsets = &offsets_i;
		else if (offsets_i != *offsets)
			throw Exception("Lengths of all arrays passsed to " + getName() + " must be equal.",
				ErrorCodes::SIZES_OF_ARRAYS_DOESNT_MATCH);
		data_columns[i] = &array->getData();
	}

	const ColumnArray * first_array = typeid_cast<const ColumnArray *>(array_columns[0].get());
	auto res = std::make_shared<ColumnUInt32>();
	block.getByPosition(result).column = res;

	ColumnUInt32::Container_t & res_values = res->getData();
	res_values.resize(offsets->size());

	if (arguments.size() == 1)
	{
		if (!(	executeNumber<UInt8>	(first_array, res_values)
			||	executeNumber<UInt16>	(first_array, res_values)
			||	executeNumber<UInt32>	(first_array, res_values)
			||	executeNumber<UInt64>	(first_array, res_values)
			||	executeNumber<Int8>		(first_array, res_values)
			||	executeNumber<Int16>	(first_array, res_values)
			||	executeNumber<Int32>	(first_array, res_values)
			||	executeNumber<Int64>	(first_array, res_values)
			||	executeNumber<Float32>	(first_array, res_values)
			||	executeNumber<Float64>	(first_array, res_values)
			||	executeString			(first_array, res_values)))
			throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName()
					+ " of first argument of function " + getName(),
				ErrorCodes::ILLEGAL_COLUMN);
	}
	else
	{
		if (!execute128bit(*offsets, data_columns, res_values))
			executeHashed(*offsets, data_columns, res_values);
	}
}

template <typename T>
bool FunctionArrayUniq::executeNumber(const ColumnArray * array, ColumnUInt32::Container_t & res_values)
{
	const ColumnVector<T> * nested = typeid_cast<const ColumnVector<T> *>(&array->getData());
	if (!nested)
		return false;
	const ColumnArray::Offsets_t & offsets = array->getOffsets();
	const typename ColumnVector<T>::Container_t & values = nested->getData();

	typedef ClearableHashSet<T, DefaultHash<T>, HashTableGrower<INITIAL_SIZE_DEGREE>,
		HashTableAllocatorWithStackMemory<(1 << INITIAL_SIZE_DEGREE) * sizeof(T)> > Set;

	Set set;
	size_t prev_off = 0;
	for (size_t i = 0; i < offsets.size(); ++i)
	{
		set.clear();
		size_t off = offsets[i];
		for (size_t j = prev_off; j < off; ++j)
			set.insert(values[j]);

		res_values[i] = set.size();
		prev_off = off;
	}
	return true;
}

bool FunctionArrayUniq::executeString(const ColumnArray * array, ColumnUInt32::Container_t & res_values)
{
	const ColumnString * nested = typeid_cast<const ColumnString *>(&array->getData());
	if (!nested)
		return false;
	const ColumnArray::Offsets_t & offsets = array->getOffsets();

	typedef ClearableHashSet<StringRef, StringRefHash, HashTableGrower<INITIAL_SIZE_DEGREE>,
		HashTableAllocatorWithStackMemory<(1 << INITIAL_SIZE_DEGREE) * sizeof(StringRef)> > Set;

	Set set;
	size_t prev_off = 0;
	for (size_t i = 0; i < offsets.size(); ++i)
	{
		set.clear();
		size_t off = offsets[i];
		for (size_t j = prev_off; j < off; ++j)
			set.insert(nested->getDataAt(j));

		res_values[i] = set.size();
		prev_off = off;
	}
	return true;
}

bool FunctionArrayUniq::executeConst(Block & block, const ColumnNumbers & arguments, size_t result)
{
	const ColumnConstArray * array = typeid_cast<const ColumnConstArray *>(block.getByPosition(arguments[0]).column.get());
	if (!array)
		return false;
	const Array & values = array->getData();

	std::set<Field> set;
	for (size_t i = 0; i < values.size(); ++i)
		set.insert(values[i]);

	block.getByPosition(result).column = std::make_shared<ColumnConstUInt32>(array->size(), set.size());
	return true;
}

bool FunctionArrayUniq::execute128bit(
	const ColumnArray::Offsets_t & offsets,
	const ConstColumnPlainPtrs & columns,
	ColumnUInt32::Container_t & res_values)
{
	size_t count = columns.size();
	size_t keys_bytes = 0;
	Sizes key_sizes(count);
	for (size_t j = 0; j < count; ++j)
	{
		if (!columns[j]->isFixed())
			return false;
		key_sizes[j] = columns[j]->sizeOfField();
		keys_bytes += key_sizes[j];
	}
	if (keys_bytes > 16)
		return false;

	typedef ClearableHashSet<UInt128, UInt128HashCRC32, HashTableGrower<INITIAL_SIZE_DEGREE>,
		HashTableAllocatorWithStackMemory<(1 << INITIAL_SIZE_DEGREE) * sizeof(UInt128)> > Set;

	Set set;
	size_t prev_off = 0;
	for (size_t i = 0; i < offsets.size(); ++i)
	{
		set.clear();
		size_t off = offsets[i];
		for (size_t j = prev_off; j < off; ++j)
			set.insert(packFixed<UInt128>(j, count, columns, key_sizes));

		res_values[i] = set.size();
		prev_off = off;
	}

	return true;
}

void FunctionArrayUniq::executeHashed(
	const ColumnArray::Offsets_t & offsets,
	const ConstColumnPlainPtrs & columns,
	ColumnUInt32::Container_t & res_values)
{
	size_t count = columns.size();

	typedef ClearableHashSet<UInt128, UInt128TrivialHash, HashTableGrower<INITIAL_SIZE_DEGREE>,
		HashTableAllocatorWithStackMemory<(1 << INITIAL_SIZE_DEGREE) * sizeof(UInt128)> > Set;

	Set set;
	size_t prev_off = 0;
	for (size_t i = 0; i < offsets.size(); ++i)
	{
		set.clear();
		size_t off = offsets[i];
		for (size_t j = prev_off; j < off; ++j)
			set.insert(hash128(j, count, columns));

		res_values[i] = set.size();
		prev_off = off;
	}
}

/// Implementation of FunctionArrayEnumerateUniq.

FunctionPtr FunctionArrayEnumerateUniq::create(const Context & context)
{
	return std::make_shared<FunctionArrayEnumerateUniq>();
}

/// Получить имя функции.
String FunctionArrayEnumerateUniq::getName() const
{
	return name;
}

DataTypePtr FunctionArrayEnumerateUniq::getReturnTypeImpl(const DataTypes & arguments) const
{
	if (arguments.size() == 0)
		throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
			+ toString(arguments.size()) + ", should be at least 1.",
			ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

	for (size_t i = 0; i < arguments.size(); ++i)
	{
		const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(arguments[i].get());
		if (!array_type)
			throw Exception("All arguments for function " + getName() + " must be arrays; argument " + toString(i + 1) + " isn't.",
				ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
	}

	return std::make_shared<DataTypeArray>(std::make_shared<DataTypeUInt32>());
}

void FunctionArrayEnumerateUniq::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
	if (arguments.size() == 1 && executeConst(block, arguments, result))
		return;

	Columns array_columns(arguments.size());
	const ColumnArray::Offsets_t * offsets = nullptr;
	ConstColumnPlainPtrs data_columns(arguments.size());

	for (size_t i = 0; i < arguments.size(); ++i)
	{
		ColumnPtr array_ptr = block.getByPosition(arguments[i]).column;
		const ColumnArray * array = typeid_cast<const ColumnArray *>(array_ptr.get());
		if (!array)
		{
			const ColumnConstArray * const_array = typeid_cast<const ColumnConstArray *>(
				block.getByPosition(arguments[i]).column.get());
			if (!const_array)
				throw Exception("Illegal column " + block.getByPosition(arguments[i]).column->getName()
					+ " of " + toString(i + 1) + "-th argument of function " + getName(),
					ErrorCodes::ILLEGAL_COLUMN);
			array_ptr = const_array->convertToFullColumn();
			array = typeid_cast<const ColumnArray *>(array_ptr.get());
		}
		array_columns[i] = array_ptr;
		const ColumnArray::Offsets_t & offsets_i = array->getOffsets();
		if (!i)
			offsets = &offsets_i;
		else if (offsets_i != *offsets)
			throw Exception("Lengths of all arrays passsed to " + getName() + " must be equal.",
				ErrorCodes::SIZES_OF_ARRAYS_DOESNT_MATCH);
		data_columns[i] = &array->getData();
	}

	const ColumnArray * first_array = typeid_cast<const ColumnArray *>(array_columns[0].get());
	auto res_nested = std::make_shared<ColumnUInt32>();
	auto res_array = std::make_shared<ColumnArray>(res_nested, first_array->getOffsetsColumn());
	block.getByPosition(result).column = res_array;

	ColumnUInt32::Container_t & res_values = res_nested->getData();
	if (!offsets->empty())
		res_values.resize(offsets->back());

	if (arguments.size() == 1)
	{
		if (!(	executeNumber<UInt8>	(first_array, res_values)
			||	executeNumber<UInt16>	(first_array, res_values)
			||	executeNumber<UInt32>	(first_array, res_values)
			||	executeNumber<UInt64>	(first_array, res_values)
			||	executeNumber<Int8>		(first_array, res_values)
			||	executeNumber<Int16>	(first_array, res_values)
			||	executeNumber<Int32>	(first_array, res_values)
			||	executeNumber<Int64>	(first_array, res_values)
			||	executeNumber<Float32>	(first_array, res_values)
			||	executeNumber<Float64>	(first_array, res_values)
			||	executeString			(first_array, res_values)))
			throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName()
					+ " of first argument of function " + getName(),
				ErrorCodes::ILLEGAL_COLUMN);
	}
	else
	{
		if (!execute128bit(*offsets, data_columns, res_values))
			executeHashed(*offsets, data_columns, res_values);
	}
}

template <typename T>
bool FunctionArrayEnumerateUniq::executeNumber(const ColumnArray * array, ColumnUInt32::Container_t & res_values)
{
	const ColumnVector<T> * nested = typeid_cast<const ColumnVector<T> *>(&array->getData());
	if (!nested)
		return false;
	const ColumnArray::Offsets_t & offsets = array->getOffsets();
	const typename ColumnVector<T>::Container_t & values = nested->getData();

	typedef ClearableHashMap<T, UInt32, DefaultHash<T>, HashTableGrower<INITIAL_SIZE_DEGREE>,
		HashTableAllocatorWithStackMemory<(1 << INITIAL_SIZE_DEGREE) * sizeof(T)> > ValuesToIndices;

	ValuesToIndices indices;
	size_t prev_off = 0;
	for (size_t i = 0; i < offsets.size(); ++i)
	{
		indices.clear();
		size_t off = offsets[i];
		for (size_t j = prev_off; j < off; ++j)
		{
			res_values[j] = ++indices[values[j]];
		}
		prev_off = off;
	}
	return true;
}

bool FunctionArrayEnumerateUniq::executeString(const ColumnArray * array, ColumnUInt32::Container_t & res_values)
{
	const ColumnString * nested = typeid_cast<const ColumnString *>(&array->getData());
	if (!nested)
		return false;
	const ColumnArray::Offsets_t & offsets = array->getOffsets();

	size_t prev_off = 0;
	typedef ClearableHashMap<StringRef, UInt32, StringRefHash, HashTableGrower<INITIAL_SIZE_DEGREE>,
		HashTableAllocatorWithStackMemory<(1 << INITIAL_SIZE_DEGREE) * sizeof(StringRef)> > ValuesToIndices;

	ValuesToIndices indices;
	for (size_t i = 0; i < offsets.size(); ++i)
	{
		indices.clear();
		size_t off = offsets[i];
		for (size_t j = prev_off; j < off; ++j)
		{
			res_values[j] = ++indices[nested->getDataAt(j)];
		}
		prev_off = off;
	}
	return true;
}

bool FunctionArrayEnumerateUniq::executeConst(Block & block, const ColumnNumbers & arguments, size_t result)
{
	const ColumnConstArray * array = typeid_cast<const ColumnConstArray *>(block.getByPosition(arguments[0]).column.get());
	if (!array)
		return false;
	const Array & values = array->getData();

	Array res_values(values.size());
	std::map<Field, UInt32> indices;
	for (size_t i = 0; i < values.size(); ++i)
	{
		res_values[i] = static_cast<UInt64>(++indices[values[i]]);
	}

	auto res_array = std::make_shared<ColumnConstArray>(array->size(), res_values, std::make_shared<DataTypeArray>(std::make_shared<DataTypeUInt32>()));
	block.getByPosition(result).column = res_array;

	return true;
}

bool FunctionArrayEnumerateUniq::execute128bit(
	const ColumnArray::Offsets_t & offsets,
	const ConstColumnPlainPtrs & columns,
	ColumnUInt32::Container_t & res_values)
{
	size_t count = columns.size();
	size_t keys_bytes = 0;
	Sizes key_sizes(count);
	for (size_t j = 0; j < count; ++j)
	{
		if (!columns[j]->isFixed())
			return false;
		key_sizes[j] = columns[j]->sizeOfField();
		keys_bytes += key_sizes[j];
	}
	if (keys_bytes > 16)
		return false;

	typedef ClearableHashMap<UInt128, UInt32, UInt128HashCRC32, HashTableGrower<INITIAL_SIZE_DEGREE>,
		HashTableAllocatorWithStackMemory<(1 << INITIAL_SIZE_DEGREE) * sizeof(UInt128)> > ValuesToIndices;

	ValuesToIndices indices;
	size_t prev_off = 0;
	for (size_t i = 0; i < offsets.size(); ++i)
	{
		indices.clear();
		size_t off = offsets[i];
		for (size_t j = prev_off; j < off; ++j)
		{
			res_values[j] = ++indices[packFixed<UInt128>(j, count, columns, key_sizes)];
		}
		prev_off = off;
	}

	return true;
}

void FunctionArrayEnumerateUniq::executeHashed(
	const ColumnArray::Offsets_t & offsets,
	const ConstColumnPlainPtrs & columns,
	ColumnUInt32::Container_t & res_values)
{
	size_t count = columns.size();

	typedef ClearableHashMap<UInt128, UInt32, UInt128TrivialHash, HashTableGrower<INITIAL_SIZE_DEGREE>,
		HashTableAllocatorWithStackMemory<(1 << INITIAL_SIZE_DEGREE) * sizeof(UInt128)> > ValuesToIndices;

	ValuesToIndices indices;
	size_t prev_off = 0;
	for (size_t i = 0; i < offsets.size(); ++i)
	{
		indices.clear();
		size_t off = offsets[i];
		for (size_t j = prev_off; j < off; ++j)
		{
			res_values[j] = ++indices[hash128(j, count, columns)];
		}
		prev_off = off;
	}
}

/// Implementation of FunctionEmptyArrayToSingle.

FunctionPtr FunctionEmptyArrayToSingle::create(const Context & context) { return std::make_shared<FunctionEmptyArrayToSingle>(); }

String FunctionEmptyArrayToSingle::getName() const
{
	return name;
}

DataTypePtr FunctionEmptyArrayToSingle::getReturnTypeImpl(const DataTypes & arguments) const
{
	if (arguments.size() != 1)
		throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
			+ toString(arguments.size()) + ", should be 1.",
			ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

	const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(arguments[0].get());
	if (!array_type)
		throw Exception("Argument for function " + getName() + " must be array.",
			ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

	return arguments[0]->clone();
}

void FunctionEmptyArrayToSingle::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
	if (executeConst(block, arguments, result))
		return;

	const ColumnArray * array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());
	if (!array)
		throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName() + " of first argument of function " + getName(),
			ErrorCodes::ILLEGAL_COLUMN);

	ColumnPtr res_ptr = array->cloneEmpty();
	block.getByPosition(result).column = res_ptr;
	ColumnArray & res = static_cast<ColumnArray &>(*res_ptr);

	const IColumn & src_data = array->getData();
	const ColumnArray::Offsets_t & src_offsets = array->getOffsets();
	IColumn & res_data = res.getData();
	ColumnArray::Offsets_t & res_offsets = res.getOffsets();

	if (!(	executeNumber<UInt8>	(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<UInt16>	(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<UInt32>	(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<UInt64>	(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<Int8>		(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<Int16>	(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<Int32>	(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<Int64>	(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<Float32>	(src_data, src_offsets, res_data, res_offsets)
		||	executeNumber<Float64>	(src_data, src_offsets, res_data, res_offsets)
		||	executeString			(src_data, src_offsets, res_data, res_offsets)
		||	executeFixedString		(src_data, src_offsets, res_data, res_offsets)))
		throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName()
			+ " of first argument of function " + getName(),
			ErrorCodes::ILLEGAL_COLUMN);
}

bool FunctionEmptyArrayToSingle::executeConst(Block & block, const ColumnNumbers & arguments, size_t result)
{
	if (const ColumnConstArray * const_array = typeid_cast<const ColumnConstArray *>(block.getByPosition(arguments[0]).column.get()))
	{
		if (const_array->getData().empty())
		{
			auto nested_type = typeid_cast<const DataTypeArray &>(*block.getByPosition(arguments[0]).type).getNestedType();

			block.getByPosition(result).column = std::make_shared<ColumnConstArray>(
				block.rowsInFirstColumn(),
				Array{nested_type->getDefault()},
				nested_type->clone());
		}
		else
			block.getByPosition(result).column = block.getByPosition(arguments[0]).column;

		return true;
	}
	else
		return false;
}

template <typename T>
bool FunctionEmptyArrayToSingle::executeNumber(
	const IColumn & src_data, const ColumnArray::Offsets_t & src_offsets,
	IColumn & res_data_col, ColumnArray::Offsets_t & res_offsets)
{
	if (const ColumnVector<T> * src_data_concrete = typeid_cast<const ColumnVector<T> *>(&src_data))
	{
		const PaddedPODArray<T> & src_data = src_data_concrete->getData();
		PaddedPODArray<T> & res_data = typeid_cast<ColumnVector<T> &>(res_data_col).getData();
		size_t size = src_offsets.size();
		res_offsets.resize(size);
		res_data.reserve(src_data.size());

		ColumnArray::Offset_t src_prev_offset = 0;
		ColumnArray::Offset_t res_prev_offset = 0;

		for (size_t i = 0; i < size; ++i)
		{
			if (src_offsets[i] != src_prev_offset)
			{
				size_t size_to_write = src_offsets[i] - src_prev_offset;
				size_t prev_res_data_size = res_data.size();
				res_data.resize(prev_res_data_size + size_to_write);
				memcpy(&res_data[prev_res_data_size], &src_data[src_prev_offset], size_to_write * sizeof(T));
				res_prev_offset += size_to_write;
				res_offsets[i] = res_prev_offset;
			}
			else
			{
				res_data.push_back(T());
				++res_prev_offset;
				res_offsets[i] = res_prev_offset;
			}

			src_prev_offset = src_offsets[i];
		}

		return true;
	}
	else
		return false;
}

bool FunctionEmptyArrayToSingle::executeFixedString(
	const IColumn & src_data, const ColumnArray::Offsets_t & src_offsets,
	IColumn & res_data_col, ColumnArray::Offsets_t & res_offsets)
{
	if (const ColumnFixedString * src_data_concrete = typeid_cast<const ColumnFixedString *>(&src_data))
	{
		const size_t n = src_data_concrete->getN();
		const ColumnFixedString::Chars_t & src_data = src_data_concrete->getChars();
		ColumnFixedString::Chars_t & res_data = typeid_cast<ColumnFixedString &>(res_data_col).getChars();
		size_t size = src_offsets.size();
		res_offsets.resize(size);
		res_data.reserve(src_data.size());

		ColumnArray::Offset_t src_prev_offset = 0;
		ColumnArray::Offset_t res_prev_offset = 0;

		for (size_t i = 0; i < size; ++i)
		{
			if (src_offsets[i] != src_prev_offset)
			{
				size_t size_to_write = src_offsets[i] - src_prev_offset;
				size_t prev_res_data_size = res_data.size();
				res_data.resize(prev_res_data_size + size_to_write * n);
				memcpy(&res_data[prev_res_data_size], &src_data[src_prev_offset], size_to_write * n);
				res_prev_offset += size_to_write;
				res_offsets[i] = res_prev_offset;
			}
			else
			{
				size_t prev_res_data_size = res_data.size();
				res_data.resize(prev_res_data_size + n);
				memset(&res_data[prev_res_data_size], 0, n);
				++res_prev_offset;
				res_offsets[i] = res_prev_offset;
			}

			src_prev_offset = src_offsets[i];
		}

		return true;
	}
	else
		return false;
}

bool FunctionEmptyArrayToSingle::executeString(
	const IColumn & src_data, const ColumnArray::Offsets_t & src_array_offsets,
	IColumn & res_data_col, ColumnArray::Offsets_t & res_array_offsets)
{
	if (const ColumnString * src_data_concrete = typeid_cast<const ColumnString *>(&src_data))
	{
		const ColumnString::Offsets_t & src_string_offsets = src_data_concrete->getOffsets();
		ColumnString::Offsets_t & res_string_offsets = typeid_cast<ColumnString &>(res_data_col).getOffsets();

		const ColumnString::Chars_t & src_data = src_data_concrete->getChars();
		ColumnString::Chars_t & res_data = typeid_cast<ColumnString &>(res_data_col).getChars();

		size_t size = src_array_offsets.size();
		res_array_offsets.resize(size);
		res_string_offsets.reserve(src_string_offsets.size());
		res_data.reserve(src_data.size());

		ColumnArray::Offset_t src_array_prev_offset = 0;
		ColumnArray::Offset_t res_array_prev_offset = 0;

		ColumnString::Offset_t src_string_prev_offset = 0;
		ColumnString::Offset_t res_string_prev_offset = 0;

		for (size_t i = 0; i < size; ++i)
		{
			if (src_array_offsets[i] != src_array_prev_offset)
			{
				size_t array_size = src_array_offsets[i] - src_array_prev_offset;

				size_t bytes_to_copy = 0;
				size_t from_string_prev_offset_local = src_string_prev_offset;
				for (size_t j = 0; j < array_size; ++j)
				{
					size_t string_size = src_string_offsets[src_array_prev_offset + j] - from_string_prev_offset_local;

					res_string_prev_offset += string_size;
					res_string_offsets.push_back(res_string_prev_offset);

					from_string_prev_offset_local += string_size;
					bytes_to_copy += string_size;
				}

				size_t res_data_old_size = res_data.size();
				res_data.resize(res_data_old_size + bytes_to_copy);
				memcpy(&res_data[res_data_old_size], &src_data[src_string_prev_offset], bytes_to_copy);

				res_array_prev_offset += array_size;
				res_array_offsets[i] = res_array_prev_offset;
			}
			else
			{
				res_data.push_back(0);	/// Пустая строка, включая ноль на конце.

				++res_string_prev_offset;
				res_string_offsets.push_back(res_string_prev_offset);

				++res_array_prev_offset;
				res_array_offsets[i] = res_array_prev_offset;
			}

			src_array_prev_offset = src_array_offsets[i];

			if (src_array_prev_offset)
				src_string_prev_offset = src_string_offsets[src_array_prev_offset - 1];
		}

		return true;
	}
	else
		return false;
}

/// Implementation of FunctionArrayReverse.

FunctionPtr FunctionArrayReverse::create(const Context & context)
{
	return std::make_shared<FunctionArrayReverse>();
}

String FunctionArrayReverse::getName() const
{
	return name;
}

DataTypePtr FunctionArrayReverse::getReturnTypeImpl(const DataTypes & arguments) const
{
	if (arguments.size() != 1)
		throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
			+ toString(arguments.size()) + ", should be 1.",
			ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

	const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(arguments[0].get());
	if (!array_type)
		throw Exception("Argument for function " + getName() + " must be array.",
			ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

	return arguments[0]->clone();
}

void FunctionArrayReverse::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
	if (executeConst(block, arguments, result))
		return;

	const ColumnArray * array = typeid_cast<const ColumnArray *>(block.getByPosition(arguments[0]).column.get());
	if (!array)
		throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName() + " of first argument of function " + getName(),
			ErrorCodes::ILLEGAL_COLUMN);

	ColumnPtr res_ptr = array->cloneEmpty();
	block.getByPosition(result).column = res_ptr;
	ColumnArray & res = static_cast<ColumnArray &>(*res_ptr);

	const IColumn & src_data = array->getData();
	const ColumnArray::Offsets_t & offsets = array->getOffsets();
	IColumn & res_data = res.getData();
	res.getOffsetsColumn() = array->getOffsetsColumn();

	if (!(	executeNumber<UInt8>	(src_data, offsets, res_data)
		||	executeNumber<UInt16>	(src_data, offsets, res_data)
		||	executeNumber<UInt32>	(src_data, offsets, res_data)
		||	executeNumber<UInt64>	(src_data, offsets, res_data)
		||	executeNumber<Int8>		(src_data, offsets, res_data)
		||	executeNumber<Int16>	(src_data, offsets, res_data)
		||	executeNumber<Int32>	(src_data, offsets, res_data)
		||	executeNumber<Int64>	(src_data, offsets, res_data)
		||	executeNumber<Float32>	(src_data, offsets, res_data)
		||	executeNumber<Float64>	(src_data, offsets, res_data)
		||	executeString			(src_data, offsets, res_data)
		||	executeFixedString		(src_data, offsets, res_data)))
		throw Exception("Illegal column " + block.getByPosition(arguments[0]).column->getName()
			+ " of first argument of function " + getName(),
			ErrorCodes::ILLEGAL_COLUMN);
}

bool FunctionArrayReverse::executeConst(Block & block, const ColumnNumbers & arguments, size_t result)
{
	if (const ColumnConstArray * const_array = typeid_cast<const ColumnConstArray *>(block.getByPosition(arguments[0]).column.get()))
	{
		const Array & arr = const_array->getData();

		size_t size = arr.size();
		Array res(size);

		for (size_t i = 0; i < size; ++i)
			res[i] = arr[size - i - 1];

		block.getByPosition(result).column = std::make_shared<ColumnConstArray>(
			block.rowsInFirstColumn(),
			res,
			block.getByPosition(arguments[0]).type->clone());

		return true;
	}
	else
		return false;
}

template <typename T>
bool FunctionArrayReverse::executeNumber(
	const IColumn & src_data, const ColumnArray::Offsets_t & src_offsets,
	IColumn & res_data_col)
{
	if (const ColumnVector<T> * src_data_concrete = typeid_cast<const ColumnVector<T> *>(&src_data))
	{
		const PaddedPODArray<T> & src_data = src_data_concrete->getData();
		PaddedPODArray<T> & res_data = typeid_cast<ColumnVector<T> &>(res_data_col).getData();
		size_t size = src_offsets.size();
		res_data.resize(src_data.size());

		ColumnArray::Offset_t src_prev_offset = 0;

		for (size_t i = 0; i < size; ++i)
		{
			const T * src = &src_data[src_prev_offset];
			const T * src_end = &src_data[src_offsets[i]];

			if (src == src_end)
				continue;

			T * dst = &res_data[src_offsets[i] - 1];

			while (src < src_end)
			{
				*dst = *src;
				++src;
				--dst;
			}

			src_prev_offset = src_offsets[i];
		}

		return true;
	}
	else
		return false;
}

bool FunctionArrayReverse::executeFixedString(
	const IColumn & src_data, const ColumnArray::Offsets_t & src_offsets,
	IColumn & res_data_col)
{
	if (const ColumnFixedString * src_data_concrete = typeid_cast<const ColumnFixedString *>(&src_data))
	{
		const size_t n = src_data_concrete->getN();
		const ColumnFixedString::Chars_t & src_data = src_data_concrete->getChars();
		ColumnFixedString::Chars_t & res_data = typeid_cast<ColumnFixedString &>(res_data_col).getChars();
		size_t size = src_offsets.size();
		res_data.resize(src_data.size());

		ColumnArray::Offset_t src_prev_offset = 0;

		for (size_t i = 0; i < size; ++i)
		{
			const UInt8 * src = &src_data[src_prev_offset * n];
			const UInt8 * src_end = &src_data[src_offsets[i] * n];

			if (src == src_end)
				continue;

			UInt8 * dst = &res_data[src_offsets[i] * n - n];

			while (src < src_end)
			{
				memcpySmallAllowReadWriteOverflow15(dst, src, n);
				src += n;
				dst -= n;
			}

			src_prev_offset = src_offsets[i];
		}

		return true;
	}
	else
		return false;
}

bool FunctionArrayReverse::executeString(
	const IColumn & src_data, const ColumnArray::Offsets_t & src_array_offsets,
	IColumn & res_data_col)
{
	if (const ColumnString * src_data_concrete = typeid_cast<const ColumnString *>(&src_data))
	{
		const ColumnString::Offsets_t & src_string_offsets = src_data_concrete->getOffsets();
		ColumnString::Offsets_t & res_string_offsets = typeid_cast<ColumnString &>(res_data_col).getOffsets();

		const ColumnString::Chars_t & src_data = src_data_concrete->getChars();
		ColumnString::Chars_t & res_data = typeid_cast<ColumnString &>(res_data_col).getChars();

		size_t size = src_array_offsets.size();
		res_string_offsets.resize(src_string_offsets.size());
		res_data.resize(src_data.size());

		ColumnArray::Offset_t src_array_prev_offset = 0;
		ColumnString::Offset_t res_string_prev_offset = 0;

		for (size_t i = 0; i < size; ++i)
		{
			if (src_array_offsets[i] != src_array_prev_offset)
			{
				size_t array_size = src_array_offsets[i] - src_array_prev_offset;

				for (size_t j = 0; j < array_size; ++j)
				{
					size_t j_reversed = array_size - j - 1;

					auto src_pos = src_array_prev_offset + j_reversed == 0 ? 0 : src_string_offsets[src_array_prev_offset + j_reversed - 1];
					size_t string_size = src_string_offsets[src_array_prev_offset + j_reversed] - src_pos;

					memcpySmallAllowReadWriteOverflow15(&res_data[res_string_prev_offset], &src_data[src_pos], string_size);

					res_string_prev_offset += string_size;
					res_string_offsets[src_array_prev_offset + j] = res_string_prev_offset;
				}
			}

			src_array_prev_offset = src_array_offsets[i];
		}

		return true;
	}
	else
		return false;
}

/// Implementation of FunctionArrayReduce.

FunctionPtr FunctionArrayReduce::create(const Context & context)
{
	return std::make_shared<FunctionArrayReduce>();
}

String FunctionArrayReduce::getName() const
{
	return name;
}

void FunctionArrayReduce::getReturnTypeAndPrerequisitesImpl(
	const ColumnsWithTypeAndName & arguments,
	DataTypePtr & out_return_type,
	std::vector<ExpressionAction> & out_prerequisites)
{
	/// Первый аргумент - константная строка с именем агрегатной функции (возможно, с параметрами в скобках, например: "quantile(0.99)").

	if (arguments.size() < 2)
		throw Exception("Number of arguments for function " + getName() + " doesn't match: passed "
			+ toString(arguments.size()) + ", should be at least 2.",
			ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

	const ColumnConstString * aggregate_function_name_column = typeid_cast<const ColumnConstString *>(arguments[0].column.get());
	if (!aggregate_function_name_column)
		throw Exception("First argument for function " + getName() + " must be constant string: name of aggregate function.",
			ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

	DataTypes argument_types(arguments.size() - 1);
	for (size_t i = 1, size = arguments.size(); i < size; ++i)
	{
		const DataTypeArray * arg = typeid_cast<const DataTypeArray *>(arguments[i].type.get());
		if (!arg)
			throw Exception("Argument " + toString(i) + " for function " + getName() + " must be array.",
				ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

		argument_types[i - 1] = arg->getNestedType()->clone();
	}

	if (!aggregate_function)
	{
		const String & aggregate_function_name_with_params = aggregate_function_name_column->getData();

		if (aggregate_function_name_with_params.empty())
			throw Exception("First argument for function " + getName() + " (name of aggregate function) cannot be empty.",
				ErrorCodes::BAD_ARGUMENTS);

		bool has_parameters = ')' == aggregate_function_name_with_params.back();

		String aggregate_function_name = aggregate_function_name_with_params;
		String parameters;
		Array params_row;

		if (has_parameters)
		{
			size_t pos = aggregate_function_name_with_params.find('(');
			if (pos == std::string::npos || pos + 2 >= aggregate_function_name_with_params.size())
				throw Exception("First argument for function " + getName() + " doesn't look like aggregate function name.",
					ErrorCodes::BAD_ARGUMENTS);

			aggregate_function_name = aggregate_function_name_with_params.substr(0, pos);
			parameters = aggregate_function_name_with_params.substr(pos + 1, aggregate_function_name_with_params.size() - pos - 2);

			if (aggregate_function_name.empty())
				throw Exception("First argument for function " + getName() + " doesn't look like aggregate function name.",
					ErrorCodes::BAD_ARGUMENTS);

			ParserExpressionList params_parser(false);
			ASTPtr args_ast = parseQuery(params_parser,
				parameters.data(), parameters.data() + parameters.size(),
				"parameters of aggregate function");

			ASTExpressionList & args_list = typeid_cast<ASTExpressionList &>(*args_ast);

			if (args_list.children.empty())
				throw Exception("Incorrect list of parameters to aggregate function "
					+ aggregate_function_name, ErrorCodes::BAD_ARGUMENTS);

			params_row.reserve(args_list.children.size());
			for (const auto & child : args_list.children)
			{
				const ASTLiteral * lit = typeid_cast<const ASTLiteral *>(child.get());
				if (!lit)
					throw Exception("Parameters to aggregate functions must be literals",
						ErrorCodes::PARAMETERS_TO_AGGREGATE_FUNCTIONS_MUST_BE_LITERALS);

				params_row.push_back(lit->value);
			}
		}

		aggregate_function = AggregateFunctionFactory().get(aggregate_function_name, argument_types);

		/// Потому что владение состояниями агрегатных функций никуда не отдаётся.
		if (aggregate_function->isState())
			throw Exception("Using aggregate function with -State modifier in function arrayReduce is not supported", ErrorCodes::BAD_ARGUMENTS);

		if (has_parameters)
			aggregate_function->setParameters(params_row);
		aggregate_function->setArguments(argument_types);
	}

	out_return_type = aggregate_function->getReturnType();
}

void FunctionArrayReduce::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
	IAggregateFunction & agg_func = *aggregate_function.get();
	std::unique_ptr<char[]> place_holder { new char[agg_func.sizeOfData()] };
	AggregateDataPtr place = place_holder.get();

	size_t rows = block.rowsInFirstColumn();

	/// Агрегатные функции не поддерживают константные столбцы. Поэтому, материализуем их.
	std::vector<ColumnPtr> materialized_columns;

	std::vector<const IColumn *> aggregate_arguments_vec(arguments.size() - 1);

	for (size_t i = 0, size = arguments.size() - 1; i < size; ++i)
	{
		const IColumn * col = block.unsafeGetByPosition(arguments[i + 1]).column.get();
		if (const ColumnArray * arr = typeid_cast<const ColumnArray *>(col))
		{
			aggregate_arguments_vec[i] = arr->getDataPtr().get();
		}
		else if (const ColumnConstArray * arr = typeid_cast<const ColumnConstArray *>(col))
		{
			materialized_columns.emplace_back(arr->convertToFullColumn());
			aggregate_arguments_vec[i] = typeid_cast<const ColumnArray &>(*materialized_columns.back().get()).getDataPtr().get();
		}
		else
			throw Exception("Illegal column " + col->getName() + " as argument of function " + getName(), ErrorCodes::ILLEGAL_COLUMN);

	}
	const IColumn ** aggregate_arguments = aggregate_arguments_vec.data();

	const ColumnArray::Offsets_t & offsets = typeid_cast<const ColumnArray &>(!materialized_columns.empty()
		? *materialized_columns.front().get()
		: *block.unsafeGetByPosition(arguments[1]).column.get()).getOffsets();

	ColumnPtr result_holder = block.getByPosition(result).type->createColumn();
	block.getByPosition(result).column = result_holder;
	IColumn & res_col = *result_holder.get();

	ColumnArray::Offset_t current_offset = 0;
	for (size_t i = 0; i < rows; ++i)
	{
		agg_func.create(place);
		ColumnArray::Offset_t next_offset = offsets[i];

		try
		{
			for (size_t j = current_offset; j < next_offset; ++j)
				agg_func.add(place, aggregate_arguments, j);

			agg_func.insertResultInto(place, res_col);
		}
		catch (...)
		{
			agg_func.destroy(place);
			throw;
		}

		agg_func.destroy(place);
		current_offset = next_offset;
	}
}

}