ClickHouse/dbms/include/DB/Storages/MergeTree/MergeTreeData.h

#pragma once

#include <DB/Core/SortDescription.h>
#include <DB/Interpreters/Context.h>
#include <DB/Interpreters/ExpressionActions.h>
#include <DB/Storages/IStorage.h>
#include <DB/Storages/MergeTree/ActiveDataPartSet.h>
#include <DB/Storages/MergeTree/MergeTreeSettings.h>
#include <DB/IO/ReadBufferFromString.h>
#include <DB/IO/WriteBufferFromFile.h>
#include <DB/IO/ReadBufferFromFile.h>
#include <DB/DataTypes/DataTypeString.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>
#include <DB/DataStreams/GraphiteRollupSortedBlockInputStream.h>
#include <DB/Storages/MergeTree/MergeTreeDataPart.h>


struct SimpleIncrement;


namespace DB
{

namespace ErrorCodes
{
	extern const int LOGICAL_ERROR;
	extern const int INVALID_PARTITION_NAME;
	extern const int TOO_MUCH_PARTS;
	extern const int NO_SUCH_DATA_PART;
	extern const int DUPLICATE_DATA_PART;
	extern const int DIRECTORY_ALREADY_EXISTS;
	extern const int TOO_MANY_UNEXPECTED_DATA_PARTS;
	extern const int NO_SUCH_COLUMN_IN_TABLE;
	extern const int TABLE_DIFFERS_TOO_MUCH;
}

/// Data structure for *MergeTree engines.
/// Merge tree is used for incremental sorting of data.
/// The table consists of several sorted parts.
/// During insertion new data is sorted according to the primary key and is written to the new part.
/// Parts are merged in the background according to a heuristic algorithm.
/// For each part the index file is created containing primary key values for every n-th row.
/// This allows efficient selection by primary key range predicate.
///
/// Additionally:
///
/// The date column is specified. For each part min and max dates are remembered.
/// Essentially it is an index too.
///
/// Data is partitioned by month. Parts belonging to different months are not merged - for the ease of
/// administration (data sync and backup).
///
/// File structure:
/// Part directory - / min-date _ max-date _ min-id _ max-id _ level /
/// Inside the part directory:
/// checksums.txt - contains the list of all files along with their sizes and checksums.
/// columns.txt - contains the list of all columns and their types.
/// primary.idx - contains the primary index.
/// [Column].bin - contains compressed column data.
/// [Column].mrk - marks, pointing to seek positions allowing to skip n * k rows.
///
/// Several modes are implemented. Modes determine additional actions during merge:
/// - Ordinary - don't do anything special
/// - Collapsing - collapse pairs of rows with the opposite values of sign_columns for the same values
///   of primary key (cf. CollapsingSortedBlockInputStream.h)
/// - Replacing - for all rows with the same primary key keep only the latest one. Or, if the version
///   column is set, keep the latest row with the maximal version.
/// - Summing - sum all numeric columns not contained in the primary key for all rows with the same primary key.
/// - Aggregating - merge columns containing aggregate function states for all rows with the same primary key.
/// - Unsorted - during the merge the data is not sorted but merely concatenated; this allows reading the data
///   in the same batches as they were written.
/// - Graphite - performs coarsening of historical data for Graphite (a system for quantitative monitoring).

/// The MergeTreeData class contains a list of parts and the data structure parameters.
/// To read and modify the data use other classes:
/// - MergeTreeDataSelectExecutor
/// - MergeTreeDataWriter
/// - MergeTreeDataMerger

 class MergeTreeData : public ITableDeclaration
{
	friend class ReshardingWorker;

public:
	/// Function to call if the part is suspected to contain corrupt data.
	using BrokenPartCallback = std::function<void (const String &)>;
	using DataPart = MergeTreeDataPart;

	using MutableDataPartPtr = std::shared_ptr<DataPart>;
	/// After the DataPart is added to the working set, it cannot be changed.
	using DataPartPtr = std::shared_ptr<const DataPart>;
	struct DataPartPtrLess { bool operator() (const DataPartPtr & lhs, const DataPartPtr & rhs) const { return *lhs < *rhs; } };
	using DataParts = std::set<DataPartPtr, DataPartPtrLess>;
	using DataPartsVector = std::vector<DataPartPtr>;

	/// For resharding.
	using MutableDataParts = std::set<MutableDataPartPtr, DataPartPtrLess>;
	using PerShardDataParts = std::unordered_map<size_t, MutableDataPartPtr>;

	/// Some operations on the set of parts return a Transaction object.
	/// If neither commit() nor rollback() was called, the destructor rollbacks the operation.
	class Transaction : private boost::noncopyable
	{
	public:
		Transaction() {}

		void commit()
		{
			clear();
		}

		void rollback()
		{
			if (data && (!parts_to_remove_on_rollback.empty() || !parts_to_add_on_rollback.empty()))
			{
				LOG_DEBUG(data->log, "Undoing transaction");
				data->replaceParts(parts_to_remove_on_rollback, parts_to_add_on_rollback, true);

				clear();
			}
		}

		~Transaction()
		{
			try
			{
				rollback();
			}
			catch(...)
			{
				tryLogCurrentException("~MergeTreeData::Transaction");
			}
		}
	private:
		friend class MergeTreeData;

		MergeTreeData * data = nullptr;

		/// What to do on rollback.
		DataPartsVector parts_to_remove_on_rollback;
		DataPartsVector parts_to_add_on_rollback;

		void clear()
		{
			data = nullptr;
			parts_to_remove_on_rollback.clear();
			parts_to_add_on_rollback.clear();
		}
	};

	/// An object that stores the names of temporary files created in the part directory during ALTER of its
	/// columns.
	class AlterDataPartTransaction : private boost::noncopyable
	{
	public:
		/// Renames temporary files, finishing the ALTER of the part.
		void commit();

		/// If commit() was not called, deletes temporary files, canceling the ALTER.
		~AlterDataPartTransaction();

		/// Review the changes before the commit.
		const NamesAndTypesList & getNewColumns() const { return new_columns; }
		const DataPart::Checksums & getNewChecksums() const { return new_checksums; }

	private:
		friend class MergeTreeData;

		AlterDataPartTransaction(DataPartPtr data_part_) : data_part(data_part_), alter_lock(data_part->alter_mutex) {}

		void clear()
		{
			alter_lock.unlock();
			data_part = nullptr;
		}

		DataPartPtr data_part;
		std::unique_lock<std::mutex> alter_lock;

		DataPart::Checksums new_checksums;
		NamesAndTypesList new_columns;
		/// If the value is an empty string, the file is not temporary, and it must be deleted.
		NameToNameMap rename_map;
	};

	using AlterDataPartTransactionPtr = std::unique_ptr<AlterDataPartTransaction>;


	/// Parameters for various modes.
	struct MergingParams
	{
		/// Merging mode. See above.
		enum Mode
		{
			Ordinary 	= 0,	/// Enum values are saved. Do not change them.
			Collapsing 	= 1,
			Summing 	= 2,
			Aggregating = 3,
			Unsorted 	= 4,
			Replacing	= 5,
			Graphite	= 6,
		};

		Mode mode;

		/// For collapsing mode.
		String sign_column;

		/// For Summing mode. If empty - columns_to_sum is determined automatically.
		Names columns_to_sum;

		/// For Replacing mode. Can be empty.
		String version_column;

		/// For Graphite mode.
		Graphite::Params graphite_params;

		/// Check that needed columns are present and have correct types.
		void check(const NamesAndTypesList & columns) const;

		String getModeName() const;
	};


	/// Attach the table corresponding to the directory in full_path (must end with /), with the given columns.
	/// Correctness of names and paths is not checked.
	///
	/// primary_expr_ast - expression used for sorting; empty for UnsortedMergeTree.
	/// index_granularity - how many rows correspond to one primary key value.
	/// require_part_metadata - should checksums.txt and columns.txt exist in the part directory.
	/// attach - whether the existing table is attached or the new table is created.
	MergeTreeData(	const String & full_path_, NamesAndTypesListPtr columns_,
					const NamesAndTypesList & materialized_columns_,
					const NamesAndTypesList & alias_columns_,
					const ColumnDefaults & column_defaults_,
					Context & context_,
					ASTPtr & primary_expr_ast_,
					const String & date_column_name_,
					const ASTPtr & sampling_expression_, /// nullptr, if sampling is not supported.
					size_t index_granularity_,
					const MergingParams & merging_params_,
					const MergeTreeSettings & settings_,
					const String & log_name_,
					bool require_part_metadata_,
					bool attach,
					BrokenPartCallback broken_part_callback_ = [](const String &){});

	/// Load the set of data parts from disk. Call once - immediately after the object is created.
	void loadDataParts(bool skip_sanity_checks);

	bool supportsSampling() const { return !!sampling_expression; }
	bool supportsPrewhere() const { return true; }

	bool supportsFinal() const
	{
		return merging_params.mode == MergingParams::Collapsing
			|| merging_params.mode == MergingParams::Summing
			|| merging_params.mode == MergingParams::Aggregating
			|| merging_params.mode == MergingParams::Replacing;
	}

	Int64 getMaxDataPartIndex();

	std::string getTableName() const override
	{
		throw Exception("Logical error: calling method getTableName of not a table.", ErrorCodes::LOGICAL_ERROR);
	}

	const NamesAndTypesList & getColumnsListImpl() const override { return *columns; }

	NameAndTypePair getColumn(const String & column_name) const override
	{
		if (column_name == "_part")
			return NameAndTypePair("_part", std::make_shared<DataTypeString>());
		if (column_name == "_part_index")
			return NameAndTypePair("_part_index", std::make_shared<DataTypeUInt64>());
		if (column_name == "_sample_factor")
			return NameAndTypePair("_sample_factor", std::make_shared<DataTypeFloat64>());

		return ITableDeclaration::getColumn(column_name);
	}

	bool hasColumn(const String & column_name) const override
	{
		return ITableDeclaration::hasColumn(column_name)
			|| column_name == "_part"
			|| column_name == "_part_index"
			|| column_name == "_sample_factor";
	}

	String getFullPath() const { return full_path; }

	String getLogName() const { return log_name; }

	/// Returns a copy of the list so that the caller shouldn't worry about locks.
	DataParts getDataParts() const;
	DataPartsVector getDataPartsVector() const;
	DataParts getAllDataParts() const;

	/// Total size of active parts in bytes.
	size_t getTotalActiveSizeInBytes() const;

	size_t getMaxPartsCountForMonth() const;

	/// Returns a pair of min block number in the given month and a bool denoting if there is at least one part.
	std::pair<Int64, bool> getMinBlockNumberForMonth(DayNum_t month) const;

	///	Returns true if block_number is contained in some part of the given month.
	bool hasBlockNumberInMonth(Int64 block_number, DayNum_t month) const;

	/// If the table contains too many active parts, sleep for a while to give them time to merge.
	/// If until is non-null, wake up from the sleep earlier if the event happened.
	void delayInsertIfNeeded(Poco::Event * until = nullptr);

	/// Returns an active part with the given name or a part containing it. If there is no such part,
	/// returns nullptr.
	DataPartPtr getActiveContainingPart(const String & part_name);

	/// Returns the part with the given name or nullptr if no such part.
	DataPartPtr getPartIfExists(const String & part_name);
	DataPartPtr getShardedPartIfExists(const String & part_name, size_t shard_no);

	/// Renames temporary part to a permanent part and adds it to the working set.
	/// If increment != nullptr, part index is determing using increment. Otherwise part index remains unchanged.
	/// It is assumed that the part does not intersect with existing parts.
	/// If out_transaction != nullptr, sets it to an object allowing to rollback part addition (but not the renaming).
	void renameTempPartAndAdd(MutableDataPartPtr & part, SimpleIncrement * increment = nullptr, Transaction * out_transaction = nullptr);

	/// The same as renameTempPartAndAdd but the part can intersect existing parts.
	/// Deletes and returns all parts covered by the added part (in ascending order).
	DataPartsVector renameTempPartAndReplace(
		MutableDataPartPtr & part, SimpleIncrement * increment = nullptr, Transaction * out_transaction = nullptr);

	/// Removes from the working set parts in remove and adds parts in add. Parts in add must already be in
	/// all_data_parts.
	/// If clear_without_timeout is true, the parts will be deleted at once, or during the next call to
	/// clearOldParts (ignoring old_parts_lifetime).
	void replaceParts(const DataPartsVector & remove, const DataPartsVector & add, bool clear_without_timeout);

	/// Adds new part to the list of known parts and to the working set.
	void attachPart(const DataPartPtr & part);

	/// Renames the part to detached/<prefix>_<part> and forgets about it. The data won't be deleted in
	/// clearOldParts.
	/// If restore_covered is true, adds to the working set inactive parts, which were merged into the deleted part.
	void renameAndDetachPart(const DataPartPtr & part, const String & prefix = "", bool restore_covered = false, bool move_to_detached = true);

	/// Removes the part from the list of parts (including all_data_parts), but doesn't move the directory.
	void detachPartInPlace(const DataPartPtr & part);

	/// Returns old inactive parts that can be deleted. At the same time removes them from the list of parts
	/// but not from the disk.
	DataPartsVector grabOldParts();

	/// Reverts the changes made by grabOldParts().
	void addOldParts(const DataPartsVector & parts);

	/// Delete irrelevant parts.
	void clearOldParts();

	void clearOldTemporaryDirectories();

	/// After the call to dropAllData() no method can be called.
	/// Deletes the data directory and flushes the uncompressed blocks cache and the marks cache.
	void dropAllData();

	/// Moves the entire data directory.
	/// Flushes the uncompressed blocks cache and the marks cache.
	/// Must be called with locked lockStructureForAlter().
	void setPath(const String & full_path, bool move_data);

	/// Check if the ALTER can be performed:
	/// - all needed columns are present.
	/// - all type conversions can be done.
	/// - columns corresponding to primary key, sign, sampling expression and date are not affected.
	/// If something is wrong, throws an exception.
	void checkAlter(const AlterCommands & params);

	/// Performs ALTER of the data part, writes the result to temporary files.
	/// Returns an object allowing to rename temporary files to permanent files.
	/// If the number of affected columns is suspiciously high and skip_sanity_checks is false, throws an exception.
	/// If no data transformations are necessary, returns nullptr.
	AlterDataPartTransactionPtr alterDataPart(
		const DataPartPtr & part,
		const NamesAndTypesList & new_columns,
		const ASTPtr & new_primary_key,
		bool skip_sanity_checks);

	/// Must be called with locked lockStructureForAlter().
	void setColumnsList(const NamesAndTypesList & new_columns) { columns = std::make_shared<NamesAndTypesList>(new_columns); }

	/// Should be called if part data is suspected to be corrupted.
	void reportBrokenPart(const String & name)
	{
		broken_part_callback(name);
	}

	ExpressionActionsPtr getPrimaryExpression() const { return primary_expr; }
	SortDescription getSortDescription() const { return sort_descr; }

	/// Check that the part is not broken and calculate the checksums for it if they are not present.
	/// Проверить, что кусок не сломан и посчитать для него чексуммы, если их нет.
	MutableDataPartPtr loadPartAndFixMetadata(const String & relative_path);

	/** Create local backup (snapshot) for parts with specified prefix.
	  * Backup is created in directory clickhouse_dir/shadow/i/, where i - incremental number,
	  *  or if 'with_name' is specified - backup is created in directory with specified name.
	  */
	void freezePartition(const std::string & prefix, const String & with_name);

	/// Returns the size of partition in bytes.
	size_t getPartitionSize(const std::string & partition_name) const;

	size_t getColumnSize(const std::string & name) const
	{
		std::lock_guard<std::mutex> lock{data_parts_mutex};

		const auto it = column_sizes.find(name);
		return it == std::end(column_sizes) ? 0 : it->second;
	}

	using ColumnSizes = std::unordered_map<std::string, size_t>;
	ColumnSizes getColumnSizes() const
	{
		std::lock_guard<std::mutex> lock{data_parts_mutex};
		return column_sizes;
	}

	size_t getColumnsTotalSize() const
	{
		std::lock_guard<std::mutex> lock{data_parts_mutex};
		size_t total_size = 0;

		for (const auto & col : column_sizes)
			total_size += col.second;
		return total_size;
	}

	/// For ATTACH/DETACH/DROP/RESHARD PARTITION.
	static String getMonthName(const Field & partition);
	static String getMonthName(DayNum_t month);
	static DayNum_t getMonthDayNum(const Field & partition);
	static DayNum_t getMonthFromName(const String & month_name);
	/// Get month from the part name or a sufficient prefix.
	static DayNum_t getMonthFromPartPrefix(const String & part_prefix);

	Context & context;
	const String date_column_name;
	const ASTPtr sampling_expression;
	const size_t index_granularity;

	/// Merging params - what additional actions to perform during merge.
	const MergingParams merging_params;

	const MergeTreeSettings settings;

	ASTPtr primary_expr_ast;
	Block primary_key_sample;
	DataTypes primary_key_data_types;

private:
	friend struct MergeTreeDataPart;
	friend class StorageMergeTree;
	friend class MergeTreeDataMerger;

	bool require_part_metadata;

	ExpressionActionsPtr primary_expr;
	SortDescription sort_descr;

	String full_path;

	NamesAndTypesListPtr columns;
	/// Current column sizes in compressed form.
	ColumnSizes column_sizes;

	BrokenPartCallback broken_part_callback;

	String log_name;
	Logger * log;

	/// Current set of data parts.
	DataParts data_parts;
	mutable std::mutex data_parts_mutex;

	/// The set of all data parts including already merged but not yet deleted. Usually it is small (tens of elements).
	/// The part is referenced from here, from the list of current parts and from each thread reading from it.
	/// This means that if reference count is 1 - the part is not used right now and can be deleted.
	DataParts all_data_parts;
	mutable std::mutex all_data_parts_mutex;

	/// Used to serialize calls to grabOldParts.
	std::mutex grab_old_parts_mutex;
	/// The same for clearOldTemporaryDirectories.
	std::mutex clear_old_temporary_directories_mutex;

	/// For each shard of the set of sharded parts.
	PerShardDataParts per_shard_data_parts;

	/// Check that columns list doesn't contain multidimensional arrays.
	/// If attach is true (attaching an existing table), writes an error message to log.
	/// Otherwise (new table or alter) throws an exception.
	void checkNoMultidimensionalArrays(const NamesAndTypesList & columns, bool attach) const;

	void initPrimaryKey();

	/// Expression for column type conversion.
	/// If no conversions are needed, out_expression=nullptr.
	/// out_rename_map maps column files for the out_expression onto new table files.
	/// out_force_update_metadata denotes if metadata must be changed even if out_rename_map is empty (used
	/// for transformation-free changing of Enum values list).
	/// Files to be deleted are mapped to an empty string in out_rename_map.
	/// If part == nullptr, just checks that all type conversions are possible.
	void createConvertExpression(const DataPartPtr & part, const NamesAndTypesList & old_columns, const NamesAndTypesList & new_columns,
		ExpressionActionsPtr & out_expression, NameToNameMap & out_rename_map, bool & out_force_update_metadata) const;

	/// Calculates column sizes in compressed form for the current state of data_parts. Call with data_parts mutex locked.
	void calculateColumnSizes();
	/// Adds or subtracts the contribution of the part to compressed column sizes.
	void addPartContributionToColumnSizes(const DataPartPtr & part);
	void removePartContributionToColumnSizes(const DataPartPtr & part);
};

}