Sharding database manager adapter. More...

#include <tkrzw_dbm_shard.h>

Classes
class	Iterator
	Iterator for each record. More...

Public Member Functions
	ShardDBM ()
	Default constructor. More...

virtual	~ShardDBM ()
	Destructor. More...

	ShardDBM (const ShardDBM &rhs)=delete
	Copy and assignment are disabled. More...

ShardDBM &	operator= (const ShardDBM &rhs)=delete

Status	Open (const std::string &path, bool writable, int32_t options=File::OPEN_DEFAULT) override
	Opens a database file. More...

Status	OpenAdvanced (const std::string &path, bool writable, int32_t options=File::OPEN_DEFAULT, const std::map< std::string, std::string > &params={}) override
	Opens a database file, in an advanced way. More...

Status	Close () override
	Closes the database file. More...

Status	Process (std::string_view key, RecordProcessor *proc, bool writable) override
	Processes a record with a processor. More...

Status	Get (std::string_view key, std::string *value=nullptr) override
	Gets the value of a record of a key. More...

Status	Set (std::string_view key, std::string_view value, bool overwrite=true, std::string *old_value=nullptr) override
	Sets a record of a key and a value. More...

Status	Remove (std::string_view key, std::string *old_value=nullptr) override
	Removes a record of a key. More...

Status	Append (std::string_view key, std::string_view value, std::string_view delim="") override
	Appends data at the end of a record of a key. More...

Status	ProcessFirst (RecordProcessor *proc, bool writable) override
	Processes the first record with a processor. More...

Status	ProcessMulti (const std::vector< std::pair< std::string_view, DBM::RecordProcessor * >> &key_proc_pairs, bool writable) override
	Processes multiple records with processors. More...

Status	CompareExchangeMulti (const std::vector< std::pair< std::string_view, std::string_view >> &expected, const std::vector< std::pair< std::string_view, std::string_view >> &desired) override
	Compares the values of records and exchanges if the condition meets. More...

Status	ProcessEach (RecordProcessor *proc, bool writable) override
	Processes each and every record in the database with a processor. More...

Status	Count (int64_t *count) override
	Gets the number of records. More...

Status	GetFileSize (int64_t *size) override
	Gets the current file size of the database. More...

Status	GetFilePath (std::string *path) override
	Gets the path of the database file. More...

Status	GetTimestamp (double *timestamp) override
	Gets the timestamp in seconds of the last modified time. More...

Status	Clear () override
	Removes all records. More...

Status	Rebuild () override
	Rebuilds the entire database. More...

Status	RebuildAdvanced (const std::map< std::string, std::string > &params={}) override
	Rebuilds the entire database, in an advanced way. More...

Status	ShouldBeRebuilt (bool *tobe) override
	Checks whether the database should be rebuilt. More...

Status	Synchronize (bool hard, FileProcessor *proc=nullptr) override
	Synchronizes the content of the database to the file system. More...

Status	SynchronizeAdvanced (bool hard, FileProcessor *proc=nullptr, const std::map< std::string, std::string > &params={}) override
	Synchronizes the content of the database to the file system, in an advanced way. More...

Status	CopyFileData (const std::string &dest_path, bool sync_hard=false) override
	Copies the content of the database files to other files. More...

std::vector< std::pair< std::string, std::string > >	Inspect () override
	Inspects the database. More...

bool	IsOpen () const override
	Checks whether the database is open. More...

bool	IsWritable () const override
	Checks whether the database is writable. More...

bool	IsHealthy () const override
	Checks whether the database condition is healthy. More...

bool	IsOrdered () const override
	Checks whether ordered operations are supported. More...

std::unique_ptr< DBM::Iterator >	MakeIterator () override
	Makes an iterator for each record. More...

std::unique_ptr< DBM >	MakeDBM () const override
	Makes a new DBM object of the same concrete class. More...

UpdateLogger *	GetUpdateLogger () const override
	Gets the logger to write all update operations. More...

void	SetUpdateLogger (UpdateLogger *update_logger) override
	Sets the logger to write all update operations. More...

DBM *	GetInternalDBM () const
	Gets the pointer to the first internal database object. More...

Public Member Functions inherited from tkrzw::ParamDBM
virtual	~ParamDBM ()=default
	Destructor. More...

Public Member Functions inherited from tkrzw::DBM
virtual	~DBM ()=default
	Destructor. More...

virtual Status	Process (std::string_view key, RecordLambdaType rec_lambda, bool writable)
	Processes a record with a lambda function. More...

virtual std::string	GetSimple (std::string_view key, std::string_view default_value="")
	Gets the value of a record of a key, in a simple way. More...

virtual Status	GetMulti (const std::vector< std::string_view > &keys, std::map< std::string, std::string > *records)
	Gets the values of multiple records of keys, with a string view vector. More...

virtual Status	GetMulti (const std::initializer_list< std::string_view > &keys, std::map< std::string, std::string > *records)
	Gets the values of multiple records of keys, with an initializer list. More...

virtual Status	GetMulti (const std::vector< std::string > &keys, std::map< std::string, std::string > *records)
	Gets the values of multiple records of keys, with a string vector. More...

virtual Status	SetMulti (const std::map< std::string_view, std::string_view > &records, bool overwrite=true)
	Sets multiple records, with a map of string views. More...

virtual Status	SetMulti (const std::initializer_list< std::pair< std::string_view, std::string_view >> &records, bool overwrite=true)
	Sets multiple records, with an initializer list. More...

virtual Status	SetMulti (const std::map< std::string, std::string > &records, bool overwrite=true)
	Sets multiple records, with a map of strings. More...

virtual Status	RemoveMulti (const std::vector< std::string_view > &keys)
	Removes records of keys, with a string view vector. More...

virtual Status	RemoveMulti (const std::initializer_list< std::string_view > &keys)
	Removes records of keys, with an initializer list. More...

virtual Status	RemoveMulti (const std::vector< std::string > &keys)
	Removes records of keys, with a string vector. More...

virtual Status	AppendMulti (const std::map< std::string_view, std::string_view > &records, std::string_view delim="")
	Appends data to multiple records, with a map of string views. More...

virtual Status	AppendMulti (const std::initializer_list< std::pair< std::string_view, std::string_view >> &records, std::string_view delim="")
	Appends data to multiple records, with an initializer list. More...

virtual Status	AppendMulti (const std::map< std::string, std::string > &records, std::string_view delim="")
	Appends data to multiple records, with a map of strings. More...

virtual Status	CompareExchange (std::string_view key, std::string_view expected, std::string_view desired, std::string actual=nullptr, bool found=nullptr)
	Compares the value of a record and exchanges if the condition meets. More...

virtual Status	Increment (std::string_view key, int64_t increment=1, int64_t *current=nullptr, int64_t initial=0)
	Increments the numeric value of a record. More...

virtual int64_t	IncrementSimple (std::string_view key, int64_t increment=1, int64_t initial=0)
	Increments the numeric value of a record, in a simple way. More...

virtual Status	ProcessMulti (const std::vector< std::pair< std::string_view, RecordProcessor * >> &key_proc_pairs, bool writable)=0
	Processes multiple records with processors. More...

virtual Status	ProcessMulti (const std::vector< std::pair< std::string_view, RecordLambdaType >> &key_lambda_pairs, bool writable)
	Processes multiple records with lambda functions. More...

virtual Status	Rekey (std::string_view old_key, std::string_view new_key, bool overwrite=true, bool copying=false, std::string *value=nullptr)
	Changes the key of a record. More...

virtual Status	ProcessFirst (RecordLambdaType rec_lambda, bool writable)
	Processes the first record with a lambda function. More...

virtual Status	PopFirst (std::string key=nullptr, std::string value=nullptr)
	Gets the first record and removes it. More...

virtual Status	PushLast (std::string_view value, double wtime=-1, std::string *key=nullptr)
	Adds a record with a key of the current timestamp. More...

virtual Status	ProcessEach (RecordLambdaType rec_lambda, bool writable)
	Processes each and every record in the database with a lambda function. More...

virtual int64_t	CountSimple ()
	Gets the number of records, in a simple way. More...

virtual int64_t	GetFileSizeSimple ()
	Gets the current file size of the database, in a simple way. More...

virtual std::string	GetFilePathSimple ()
	Gets the path of the database file, in a simple way. More...

virtual double	GetTimestampSimple ()
	Gets the timestamp of the last modified time, in a simple way. More...

virtual bool	ShouldBeRebuiltSimple ()
	Checks whether the database should be rebuilt, in a simple way. More...

virtual Status	Export (DBM *dest_dbm)
	Exports all records to another database. More...

const std::type_info &	GetType () const
	Gets the type information of the actual class. More...

Static Public Member Functions
static Status	GetNumberOfShards (const std::string &path, int32_t *num_shards)
	Gets the number of shards of a database. More...

static Status	RestoreDatabase (const std::string &old_file_path, const std::string &new_file_path, const std::string &class_name="", int64_t end_offset=-1, std::string_view cipher_key="")
	Restores a broken database as a new healthy database. More...

static Status	RenameDatabase (const std::string &old_file_path, const std::string &new_file_path)
	Renames all files of a database to ones of another name. More...

Additional Inherited Members
Public Types inherited from tkrzw::DBM
typedef std::function< std::string_view(std::string_view, std::string_view)>	RecordLambdaType
	Lambda function type to process a record. More...

Static Public Attributes inherited from tkrzw::DBM
static const std::string_view	ANY_DATA
	The special string_view value to represent any data. More...

Detailed Description

Sharding database manager adapter.

All operations except for Open and Close are thread-safe; Multiple threads can access the same database concurrently. Every opened database must be closed explicitly to avoid data corruption.

This class is a wrapper of PolyDBM for sharding the database into multiple instances.

Constructor & Destructor Documentation

◆ ShardDBM() [1/2]

tkrzw::ShardDBM::ShardDBM ( )

explicit

Default constructor.

◆ ~ShardDBM()

virtual tkrzw::ShardDBM::~ShardDBM ( )

virtual

Destructor.

◆ ShardDBM() [2/2]

tkrzw::ShardDBM::ShardDBM ( const ShardDBM & rhs )

explicitdelete

Copy and assignment are disabled.

Member Function Documentation

◆ Open()

Status tkrzw::ShardDBM::Open	(	const std::string &	path,
		bool	writable,
		int32_t	options = `File::OPEN_DEFAULT`
	)

overridevirtual

Opens a database file.

Parameters

path	A path of the file.
writable	If true, the file is writable. If false, it is read-only.
options	Bit-sum options of File::OpenOption enums for opening the file.

Returns: The result status.

Implements tkrzw::DBM.

◆ OpenAdvanced()

Status tkrzw::ShardDBM::OpenAdvanced	(	const std::string &	path,
		bool	writable,
		int32_t	options = `File::OPEN_DEFAULT`,
		const std::map< std::string, std::string > &	params = `{}`
	)

overridevirtual

Opens a database file, in an advanced way.

Parameters

path	A path of the file.
writable	If true, the file is writable. If false, it is read-only.
options	Bit-sum options for opening the file.
params	Optional parameters. All parameters for PolyDBM::OpenAdvanced are supported. Moreover, the parameter "num_shards" specifies the number of shards. Each shard file has a suffix like "-00003-of-00015". If the number of shards is not specified and existing files match the path, it is implicitly specified. If there are no matching files, 1 is implicitly set.

Returns: The result status.

Implements tkrzw::ParamDBM.

◆ Close()

Status tkrzw::ShardDBM::Close ( )

overridevirtual

Closes the database file.

Returns: The result status.

Implements tkrzw::DBM.

◆ Process()

Status tkrzw::ShardDBM::Process	(	std::string_view	key,
		RecordProcessor *	proc,
		bool	writable
	)

overridevirtual

Processes a record with a processor.

Parameters

key	The key of the record.
proc	The pointer to the processor object.
writable	True if the processor can edit the record.

Returns: The result status.

If the specified record exists, the ProcessFull of the processor is called. Otherwise, the ProcessEmpty of the processor is called.

Implements tkrzw::DBM.

◆ Get()

Status tkrzw::ShardDBM::Get	(	std::string_view	key,
		std::string *	value = `nullptr`
	)

overridevirtual

Gets the value of a record of a key.

Parameters

key	The key of the record.
value	The pointer to a string object to contain the result value. If it is nullptr, the value data is ignored.

Returns: The result status. If there's no matching record, NOT_FOUND_ERROR is returned.

Reimplemented from tkrzw::DBM.

◆ Set()

Status tkrzw::ShardDBM::Set	(	std::string_view	key,
		std::string_view	value,
		bool	overwrite = `true`,
		std::string *	old_value = `nullptr`
	)

overridevirtual

Sets a record of a key and a value.

Parameters

key	The key of the record.
value	The value of the record.
overwrite	Whether to overwrite the existing value if there's a record with the same key. If true, the existing value is overwritten by the new value. If false, the operation is given up and an error status is returned.
old_value	The pointer to a string object to contain the old value. Assignment is done even on the duplication error. If it is nullptr, it is ignored.

Returns: The result status. If overwriting is abandoned, DUPLICATION_ERROR is returned.

Reimplemented from tkrzw::DBM.

◆ Remove()

Status tkrzw::ShardDBM::Remove	(	std::string_view	key,
		std::string *	old_value = `nullptr`
	)

overridevirtual

Removes a record of a key.

Parameters

key	The key of the record.
old_value	The pointer to a string object to contain the old value. If it is nullptr, it is ignored.

Returns: The result status. If there's no matching record, NOT_FOUND_ERROR is returned.

Reimplemented from tkrzw::DBM.

◆ Append()

Status tkrzw::ShardDBM::Append	(	std::string_view	key,
		std::string_view	value,
		std::string_view	delim = `""`
	)

overridevirtual

Appends data at the end of a record of a key.

Parameters

key	The key of the record.
value	The value to append.
delim	The delimiter to put after the existing record.

Returns: The result status.

If there's no existing record, the value is set without the delimiter.

Reimplemented from tkrzw::DBM.

◆ ProcessFirst()

Status tkrzw::ShardDBM::ProcessFirst	(	RecordProcessor *	proc,
		bool	writable
	)

overridevirtual

Processes the first record with a processor.

Parameters

proc	The pointer to the processor object.
writable	True if the processor can edit the record.

Returns: The result status.

If the first record exists, the ProcessFull of the processor is called. Otherwise, this method fails and no method of the processor is called. Whereas ordered databases have efficient implementations of this method, unordered databases have inefficient implementations.

Implements tkrzw::DBM.

◆ ProcessMulti()

Status tkrzw::ShardDBM::ProcessMulti	(	const std::vector< std::pair< std::string_view, DBM::RecordProcessor * >> &	key_proc_pairs,
		bool	writable
	)

override

Processes multiple records with processors.

Parameters

key_proc_pairs	Pairs of the keys and their processor objects.
writable	True if the processors can edit the records.

Returns: The result status.

Precondition: The database is opened. The writable parameter should be consistent to the open mode.

If the specified record exists, the ProcessFull of the processor is called. Otherwise, the ProcessEmpty of the processor is called.

ShardDBM has a special implementation to assure isolation of transactions in multi-threading environments. The given keys are locked in the space of the first shard so that isolation is assured among ProcessMulti even if actual keys belongs to different shards. In other words, other methods such as Get, Set, and Remove are executed without exclusive control.

◆ CompareExchangeMulti()

Status tkrzw::ShardDBM::CompareExchangeMulti	(	const std::vector< std::pair< std::string_view, std::string_view >> &	expected,
		const std::vector< std::pair< std::string_view, std::string_view >> &	desired
	)

overridevirtual

Compares the values of records and exchanges if the condition meets.

Parameters

expected	The record keys and their expected values. If the value is nullptr, no existing record is expected. If the value is ANY_DATA, an existing record with any value is expacted.
desired	The record keys and their desired values. If the value is nullptr, the record is to be removed.

Returns: The result status. If the condition doesn't meet, INFEASIBLE_ERROR is returned.

ShardDBM has a special implementation to assure isolation of transactions in multi-threading environments. In contrast to the ProcessMulti method, isolation of CompareExchangeMulti is assured among all kinds of methods.

Reimplemented from tkrzw::DBM.

◆ ProcessEach()

Status tkrzw::ShardDBM::ProcessEach	(	RecordProcessor *	proc,
		bool	writable
	)

overridevirtual

Processes each and every record in the database with a processor.

Parameters

proc	The pointer to the processor object.
writable	True if the processor can edit the record.

Returns: The result status.

The ProcessFull of the processor is called repeatedly for each record. The ProcessEmpty of the processor is called once before the iteration and once after the iteration.

Implements tkrzw::DBM.

◆ Count()

Status tkrzw::ShardDBM::Count ( int64_t * count )

overridevirtual

Gets the number of records.

Parameters

count The pointer to an integer object to contain the result count.

Returns: The result status.

Implements tkrzw::DBM.

◆ GetFileSize()

Status tkrzw::ShardDBM::GetFileSize ( int64_t * size )

overridevirtual

Gets the current file size of the database.

Parameters

size	The pointer to an integer object to contain the result size.

Returns: The result status.

Implements tkrzw::DBM.

◆ GetFilePath()

Status tkrzw::ShardDBM::GetFilePath ( std::string * path )

overridevirtual

Gets the path of the database file.

Parameters

path	The pointer to a string object to contain the result path.

Returns: The result status.

Implements tkrzw::DBM.

◆ GetTimestamp()

Status tkrzw::ShardDBM::GetTimestamp ( double * timestamp )

overridevirtual

Gets the timestamp in seconds of the last modified time.

Parameters

timestamp The pointer to a double object to contain the timestamp.

Returns: The result status.

Implements tkrzw::DBM.

◆ Clear()

Status tkrzw::ShardDBM::Clear ( )

overridevirtual

Removes all records.

Returns: The result status.

Implements tkrzw::DBM.

◆ Rebuild()

Status tkrzw::ShardDBM::Rebuild ( )

overridevirtual

Rebuilds the entire database.

Returns: The result status.

Implements tkrzw::DBM.

◆ RebuildAdvanced()

Status tkrzw::ShardDBM::RebuildAdvanced ( const std::map< std::string, std::string > & params = {} )

overridevirtual

Rebuilds the entire database, in an advanced way.

Parameters

params Optional parameters.

Returns: The result status.

The parameters work in the same way as with PolyDBM::RebuildAdvanced.

Implements tkrzw::ParamDBM.

◆ ShouldBeRebuilt()

Status tkrzw::ShardDBM::ShouldBeRebuilt ( bool * tobe )

overridevirtual

Checks whether the database should be rebuilt.

Parameters

tobe	The pointer to a boolean object to contain the result decision.

Returns: The result status.

Implements tkrzw::DBM.

◆ Synchronize()

Status tkrzw::ShardDBM::Synchronize	(	bool	hard,
		FileProcessor *	proc = `nullptr`
	)

overridevirtual

Synchronizes the content of the database to the file system.

Parameters

hard	True to do physical synchronization with the hardware or false to do only logical synchronization with the file system.
proc	The pointer to the file processor object, whose Process method is called while the content of the file is synchronized. If it is nullptr, it is ignored.

Returns: The result status.

Implements tkrzw::DBM.

◆ SynchronizeAdvanced()

Status tkrzw::ShardDBM::SynchronizeAdvanced	(	bool	hard,
		FileProcessor *	proc = `nullptr`,
		const std::map< std::string, std::string > &	params = `{}`
	)

overridevirtual

Synchronizes the content of the database to the file system, in an advanced way.

Parameters

hard	True to do physical synchronization with the hardware or false to do only logical synchronization with the file system.
proc	The pointer to the file processor object, whose Process method is called while the content of the file is synchronized. If it is nullptr, it is ignored.
params	Optional parameters.

Returns: The result status.

The parameters work in the same way as with PolyDBM::OpenAdvanced.

Implements tkrzw::ParamDBM.

◆ CopyFileData()

Status tkrzw::ShardDBM::CopyFileData	(	const std::string &	dest_path,
		bool	sync_hard = `false`
	)

overridevirtual

Copies the content of the database files to other files.

Parameters

dest_path	A path prefix to the destination files.
sync_hard	True to do physical synchronization with the hardware.

Returns: The result status.

Copying is done while the content is synchronized and stable. So, this method is suitable for making a backup file while running a database service. Each shard file is copied and the destination file also has the same suffix.

Reimplemented from tkrzw::DBM.

◆ Inspect()

std::vector<std::pair<std::string, std::string> > tkrzw::ShardDBM::Inspect ( )

overridevirtual

Inspects the database.

Returns: A vector of pairs of a property name and its value.

Implements tkrzw::DBM.

◆ IsOpen()

bool tkrzw::ShardDBM::IsOpen ( ) const

overridevirtual

Checks whether the database is open.

Returns: True if the database is open, or false if not.

Implements tkrzw::DBM.

◆ IsWritable()

bool tkrzw::ShardDBM::IsWritable ( ) const

overridevirtual

Checks whether the database is writable.

Returns: True if the database is writable, or false if not.

Implements tkrzw::DBM.

◆ IsHealthy()

bool tkrzw::ShardDBM::IsHealthy ( ) const

overridevirtual

Checks whether the database condition is healthy.

Returns: True if the database condition is healthy, or false if not.

Implements tkrzw::DBM.

◆ IsOrdered()

bool tkrzw::ShardDBM::IsOrdered ( ) const

overridevirtual

Checks whether ordered operations are supported.

Returns: True if ordered operations are supported, or false if not.

Implements tkrzw::DBM.

◆ MakeIterator()

std::unique_ptr<DBM::Iterator> tkrzw::ShardDBM::MakeIterator ( )

overridevirtual

Makes an iterator for each record.

Returns: The iterator for each record.

Implements tkrzw::DBM.

◆ MakeDBM()

std::unique_ptr<DBM> tkrzw::ShardDBM::MakeDBM ( ) const

overridevirtual

Makes a new DBM object of the same concrete class.

Returns: The new DBM object.

Implements tkrzw::DBM.

◆ GetUpdateLogger()

UpdateLogger* tkrzw::ShardDBM::GetUpdateLogger ( ) const

overridevirtual

Gets the logger to write all update operations.

Returns: The update logger if it has been set or nullptr if it hasn't.

Implements tkrzw::DBM.

◆ SetUpdateLogger()

void tkrzw::ShardDBM::SetUpdateLogger ( UpdateLogger * update_logger )

overridevirtual

Sets the logger to write all update operations.

Parameters

update_logger The pointer to the update logger object. Ownership is not taken. If it is nullptr, no logger is used.

Implements tkrzw::DBM.

◆ GetInternalDBM()

DBM* tkrzw::ShardDBM::GetInternalDBM ( ) const

Gets the pointer to the first internal database object.

Returns: The pointer to the first internal database object, or nullptr on failure.

◆ GetNumberOfShards()

static Status tkrzw::ShardDBM::GetNumberOfShards	(	const std::string &	path,
		int32_t *	num_shards
	)

static

Gets the number of shards of a database.

Parameters

path	The database path.
num_shards	The pointer to a variable to store the result.

Returns: The result status.

If there are multiple candidates, this function report a failure.

◆ RestoreDatabase()

static Status tkrzw::ShardDBM::RestoreDatabase	(	const std::string &	old_file_path,
		const std::string &	new_file_path,
		const std::string &	class_name = `""`,
		int64_t	end_offset = `-1`,
		std::string_view	cipher_key = `""`
	)

static

Restores a broken database as a new healthy database.

Parameters

old_file_path	The path of the broken database.
new_file_path	The path of the new database to be created.
class_name	The name of the database class. If it is empty, the class is guessed from the file extension.
end_offset	The exclusive end offset of records to read. Negative means unlimited. 0 means the size when the database is synched or closed properly. Using a positive value is not meaningful if the number of shards is more than one.
cipher_key	The encryption key for cipher compressors.

Returns: The result status.

◆ RenameDatabase()

static Status tkrzw::ShardDBM::RenameDatabase	(	const std::string &	old_file_path,
		const std::string &	new_file_path
	)

static

Renames all files of a database to ones of another name.

Parameters

old_file_path	The path of the database.
new_file_path	The path of the new database.

Returns: The result status.

Classes

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ShardDBM() [1/2]

◆ ~ShardDBM()

◆ ShardDBM() [2/2]

Member Function Documentation

◆ Open()

◆ OpenAdvanced()

◆ Close()

◆ Process()

◆ Get()

◆ Set()

◆ Remove()

◆ Append()

◆ ProcessFirst()

◆ ProcessMulti()

◆ CompareExchangeMulti()

◆ ProcessEach()

◆ Count()

◆ GetFileSize()

◆ GetFilePath()

◆ GetTimestamp()

◆ Clear()

◆ Rebuild()

◆ RebuildAdvanced()

◆ ShouldBeRebuilt()

◆ Synchronize()

◆ SynchronizeAdvanced()

◆ CopyFileData()

◆ Inspect()

◆ IsOpen()

◆ IsWritable()

◆ IsHealthy()

◆ IsOrdered()

◆ MakeIterator()

◆ MakeDBM()

◆ GetUpdateLogger()

◆ SetUpdateLogger()

◆ GetInternalDBM()

◆ GetNumberOfShards()

◆ RestoreDatabase()

◆ RenameDatabase()