Modules
	Error handling

	Opening & Closing

	Transactions

	Databases

	Create/Read/Update/Delete (see Quick Reference in details)

	Cursors

	Statistics & Information

	Settings

	Logging and runtime debug

	Range query estimation

	Extra operations

	Value-to-Key functions
	Value-to-Key functions to avoid using custom comparators.

	Key-to-Value functions
	Key-to-Value functions to avoid using custom comparators.

	B-tree Traversal

Classes
struct	MDBX_version_info
	libmdbx version information More...

struct	MDBX_build_info
	libmdbx build information More...

struct	MDBX_stat
	Statistics for a database in the environment. More...

struct	MDBX_envinfo
	Information about the environment. More...

struct	MDBX_txn_info
	Information about the transaction. More...

struct	MDBX_commit_latency
	Latency of commit stages in 1/65536 of seconds units. More...

struct	MDBX_canary
	The fours integers markers (aka "canary") associated with the environment. More...

struct	MDBX_version_info.git

struct	MDBX_envinfo.mi_geo

struct	MDBX_envinfo.mi_bootid
	A mostly unique ID that is regenerated on each boot. More...

struct	MDBX_envinfo.mi_bootid.current

struct	MDBX_envinfo.mi_bootid.meta0

struct	MDBX_envinfo.mi_bootid.meta1

struct	MDBX_envinfo.mi_bootid.meta2

struct	MDBX_envinfo.mi_pgop_stat

struct	MDBX_commit_latency.gc_prof
	Информация для профилирования работы GC. More...

Macros
#define	MDBX_VERSION_MAJOR 0

#define	MDBX_VERSION_MINOR 12

#define	LIBMDBX_API

#define	LIBMDBX_API_TYPE

#define	LIBMDBX_VERINFO_API __dll_export

#define	MDBX_LOCKNAME "/mdbx.lck"
	The name of the lock file in the environment without using MDBX_NOSUBDIR. More...

#define	MDBX_DATANAME "/mdbx.dat"
	The name of the data file in the environment without using MDBX_NOSUBDIR. More...

#define	MDBX_LOCK_SUFFIX "-lck"
	The suffix of the lock file when MDBX_NOSUBDIR is used. More...

#define	MDBX_MAP_RESIZED MDBX_MAP_RESIZED_is_deprecated()

Typedefs
typedef int	mdbx_filehandle_t

typedef pid_t	mdbx_pid_t

typedef pthread_t	mdbx_tid_t

typedef mode_t	mdbx_mode_t

typedef struct MDBX_env	MDBX_env
	Opaque structure for a database environment. More...

typedef struct iovec	MDBX_val
	Generic structure used for passing keys and data in and out of the database. . More...

typedef enum MDBX_txn_flags_t	MDBX_txn_flags_t

typedef enum MDBX_warmup_flags_t	MDBX_warmup_flags_t

typedef int(*	MDBX_preserve_func) (void context, MDBX_val target, const void *src, size_t bytes)

Enumerations
enum	MDBX_constants { MDBX_MAX_DBI = UINT32_C(32765) , MDBX_MAXDATASIZE = UINT32_C(0x7fff0000) , MDBX_MIN_PAGESIZE = 256 , MDBX_MAX_PAGESIZE = 65536 }

Functions
LIBMDBX_API const char *	mdbx_liberr2str (int errnum)

LIBMDBX_API int	mdbx_env_openW (MDBX_env env, const wchar_t pathname, MDBX_env_flags_t flags, mdbx_mode_t mode)
	Open an environment instance. More...

LIBMDBX_API int	mdbx_env_deleteW (const wchar_t *pathname, MDBX_env_delete_mode_t mode)
	Delete the environment's files in a proper and multiprocess-safe way. More...

LIBMDBX_API int	mdbx_env_copyW (MDBX_env env, const wchar_t dest, MDBX_copy_flags_t flags)
	Copy an MDBX environment to the specified path, with options. More...

LIBMDBX_API int	mdbx_env_get_pathW (const MDBX_env env, const wchar_t *dest)
	Return the path that was used in mdbx_env_open(). More...

LIBMDBX_API int	mdbx_dbi_open2 (MDBX_txn txn, const MDBX_val name, MDBX_db_flags_t flags, MDBX_dbi *dbi)

MDBX_DEPRECATED LIBMDBX_API int	mdbx_dbi_open_ex2 (MDBX_txn txn, const MDBX_val name, MDBX_db_flags_t flags, MDBX_dbi dbi, MDBX_cmp_func keycmp, MDBX_cmp_func *datacmp)

LIBMDBX_API int	mdbx_replace_ex (MDBX_txn txn, MDBX_dbi dbi, const MDBX_val key, MDBX_val new_data, MDBX_val old_data, MDBX_put_flags_t flags, MDBX_preserve_func preserver, void *preserver_context)

LIBMDBX_API MDBX_hsr_func *	mdbx_env_get_hsr (const MDBX_env *env)
	Gets current Handle-Slow-Readers callback used to resolve database full/overflow issue due to a reader(s) which prevents the old data from being recycled. More...

Variables
LIBMDBX_VERINFO_API const struct MDBX_version_info	mdbx_version
	libmdbx version information More...

LIBMDBX_VERINFO_API const struct MDBX_build_info	mdbx_build
	libmdbx build information More...

Detailed Description

Class Documentation

◆ MDBX_version_info

struct MDBX_version_info

libmdbx version information

Class Members
struct MDBX_version_info	git	source information from git
uint8_t	major	Major version number
uint8_t	minor	Minor version number
uint16_t	release	Release number of Major.Minor
uint32_t	revision	Revision number of Release
const char *	sourcery	sourcery anchor for pinning

◆ MDBX_build_info

struct MDBX_build_info

libmdbx build information

Attention: Some strings could be NULL in case no corresponding information was provided at build time (i.e. flags).

Class Members
const char *	compiler	compiler
const char *	datetime	build timestamp (ISO-8601 or DATE TIME)
const char *	flags	CFLAGS and CXXFLAGS
const char *	options	mdbx-related options
const char *	target	cpu/arch-system-config triplet

◆ MDBX_stat

struct MDBX_stat

Statistics for a database in the environment.

See also: mdbx_env_stat_ex(); mdbx_dbi_stat()

Class Members
uint64_t	ms_branch_pages	Number of internal (non-leaf) pages
uint32_t	ms_depth	Depth (height) of the B-tree
uint64_t	ms_entries	Number of data items
uint64_t	ms_leaf_pages	Number of leaf pages
uint64_t	ms_mod_txnid	Transaction ID of committed last modification
uint64_t	ms_overflow_pages	Number of overflow pages
uint32_t	ms_psize	Size of a database page. This is the same for all databases.

◆ MDBX_envinfo

struct MDBX_envinfo

Information about the environment.

See also: mdbx_env_info_ex()

Class Members
uint32_t	mi_autosync_period_seconds16dot16	Current auto-sync period in 1/65536 of second, see mdbx_env_set_syncperiod().
uint64_t	mi_autosync_threshold	Current auto-sync threshold, see mdbx_env_set_syncbytes().
struct MDBX_envinfo	mi_bootid	A mostly unique ID that is regenerated on each boot. As such it can be used to identify the local machine's current boot. MDBX uses such when open the database to determine whether rollback required to the last steady sync point or not. I.e. if current bootid is differ from the value within a database then the system was rebooted and all changes since last steady sync must be reverted for data integrity. Zeros mean that no relevant information is available from the system.
uint32_t	mi_dxb_pagesize	Database pagesize
struct MDBX_envinfo	mi_geo
uint64_t	mi_last_pgno	Number of the last used page
uint64_t	mi_latter_reader_txnid	ID of the last reader transaction
uint64_t	mi_mapsize	Size of the data memory map
uint32_t	mi_maxreaders	Total reader slots in the environment
uint64_t	mi_meta0_sign
uint64_t	mi_meta0_txnid
uint64_t	mi_meta1_sign
uint64_t	mi_meta1_txnid
uint64_t	mi_meta2_sign
uint64_t	mi_meta2_txnid
uint32_t	mi_mode	Current environment mode. The same as mdbx_env_get_flags() returns.
uint32_t	mi_numreaders	Max reader slots used in the environment
struct MDBX_envinfo	mi_pgop_stat	Statistics of page operations. Overall statistics of page operations of all (running, completed and aborted) transactions in the current multi-process session (since the first process opened the database after everyone had previously closed it).
uint64_t	mi_recent_txnid	ID of the last committed transaction
uint64_t	mi_self_latter_reader_txnid	ID of the last reader transaction of caller process
uint32_t	mi_since_reader_check_seconds16dot16	Time since the last readers check in 1/65536 of second, see mdbx_reader_check().
uint32_t	mi_since_sync_seconds16dot16	Time since entering to a "dirty" out-of-sync state in units of 1/65536 of second. In other words, this is the time since the last non-steady commit or zero if it was steady.
uint32_t	mi_sys_pagesize	System pagesize
uint64_t	mi_unsync_volume	Bytes not explicitly synchronized to disk

◆ MDBX_txn_info

struct MDBX_txn_info

Information about the transaction.

See also: mdbx_txn_info

Class Members
uint64_t	txn_id	The ID of the transaction. For a READ-ONLY transaction, this corresponds to the snapshot being read.
uint64_t	txn_reader_lag	For READ-ONLY transaction: the lag from a recent MVCC-snapshot, i.e. the number of committed transaction since read transaction started. For WRITE transaction (provided if `scan_rlt=true`): the lag of the oldest reader from current transaction (i.e. at least 1 if any reader running).
uint64_t	txn_space_dirty	For READ-ONLY transaction (provided if `scan_rlt=true`): The space that actually become available for reuse when only this transaction will be finished. For WRITE transaction: The summarized size of the dirty database pages that generated during this transaction.
uint64_t	txn_space_leftover	For READ-ONLY transaction: the space available for writer(s) and that must be exhausted for reason to call the Handle-Slow-Readers callback for this read transaction. For WRITE transaction: the space inside transaction that left to `MDBX_TXN_FULL` error.
uint64_t	txn_space_limit_hard	Upper bound for size the database file, i.e. the value `size_upper` argument of the appropriate call of mdbx_env_set_geometry().
uint64_t	txn_space_limit_soft	Current size of database file.
uint64_t	txn_space_retired	For READ-ONLY transaction: The total size of the database pages that were retired by committed write transactions after the reader's MVCC-snapshot, i.e. the space which would be freed after the Reader releases the MVCC-snapshot for reuse by completion read transaction. For WRITE transaction: The summarized size of the database pages that were retired for now due Copy-On-Write during this transaction.
uint64_t	txn_space_used	Used space by this transaction, i.e. corresponding to the last used database page.

◆ MDBX_commit_latency

struct MDBX_commit_latency

Latency of commit stages in 1/65536 of seconds units.

Warning: This structure may be changed in future releases.

See also: mdbx_txn_commit_ex()

Class Members
uint32_t	audit	Duration of internal audit if enabled.
uint32_t	ending	Duration of transaction ending (releasing resources).
uint32_t	gc_cputime	User-mode CPU time spent on GC update.
struct MDBX_commit_latency	gc_prof	Информация для профилирования работы GC. Note Статистика является общей для всех процессов работающих с одним файлом БД и хранится в LCK-файле. Данные аккумулируются при фиксации всех транзакций, но только в сборках libmdbx c установленной опцией MDBX_ENABLE_PROFGC. Собранная статистика возвращаются любому процессу при использовании mdbx_txn_commit_ex() и одновременно обнуляется при завершении транзакций верхнего уровня (не вложенных).
uint32_t	gc_wallclock	Duration of GC update by wall clock.
uint32_t	preparation	Duration of preparation (commit child transactions, update sub-databases records and cursors destroying).
uint32_t	sync	Duration of syncing written data to the disk/storage, i.e. the duration of a `fdatasync()` or a `msync()` syscall during commit.
uint32_t	whole	The total duration of a commit.
uint32_t	write	Duration of writing dirty/modified data pages to a filesystem, i.e. the summary duration of a `write()` syscalls during commit.

◆ MDBX_canary

struct MDBX_canary

The fours integers markers (aka "canary") associated with the environment.

See also: mdbx_canary_set(); mdbx_canary_get()

The x, y and z values could be set by mdbx_canary_put(), while the 'v' will be always set to the transaction number. Updated values becomes visible outside the current transaction only after it was committed. Current values could be retrieved by mdbx_canary_get().

Class Members
uint64_t	v
uint64_t	x
uint64_t	y
uint64_t	z

◆ MDBX_version_info.git

struct MDBX_version_info.git

Class Members
const char *	commit	tree hash, i.e. digest of the source code
const char *	datetime	committer date, strict ISO-8601 format
const char *	describe	git-describe string
const char *	tree	commit hash (hexadecimal digits)

◆ MDBX_envinfo.mi_geo

struct MDBX_envinfo.mi_geo

Class Members
uint64_t	current	Current datafile size
uint64_t	grow	Growth step for datafile
uint64_t	lower	Lower limit for datafile size
uint64_t	shrink	Shrink threshold for datafile
uint64_t	upper	Upper limit for datafile size

◆ MDBX_envinfo.mi_bootid

struct MDBX_envinfo.mi_bootid

A mostly unique ID that is regenerated on each boot.

As such it can be used to identify the local machine's current boot. MDBX uses such when open the database to determine whether rollback required to the last steady sync point or not. I.e. if current bootid is differ from the value within a database then the system was rebooted and all changes since last steady sync must be reverted for data integrity. Zeros mean that no relevant information is available from the system.

Class Members
mi_bootid	current
mi_bootid	meta0
mi_bootid	meta1
mi_bootid	meta2

◆ MDBX_envinfo.mi_bootid.current

struct MDBX_envinfo.mi_bootid.current

Class Members
uint64_t	x
uint64_t	y

◆ MDBX_envinfo.mi_bootid.meta0

struct MDBX_envinfo.mi_bootid.meta0

Class Members
uint64_t	x
uint64_t	y

◆ MDBX_envinfo.mi_bootid.meta1

struct MDBX_envinfo.mi_bootid.meta1

Class Members
uint64_t	x
uint64_t	y

◆ MDBX_envinfo.mi_bootid.meta2

struct MDBX_envinfo.mi_bootid.meta2

Class Members
uint64_t	x
uint64_t	y

◆ MDBX_envinfo.mi_pgop_stat

struct MDBX_envinfo.mi_pgop_stat

Statistics of page operations.

Overall statistics of page operations of all (running, completed and aborted) transactions in the current multi-process session (since the first process opened the database after everyone had previously closed it).

Class Members
uint64_t	clone	Quantity of parent's dirty pages clones for nested transactions
uint64_t	cow	Quantity of pages copied for update
uint64_t	fsync	Number of explicit fsync-to-disk operations (not a pages)
uint64_t	merge	Page merges
uint64_t	mincore	Number of mincore() calls
uint64_t	msync	Number of explicit msync-to-disk operations (not a pages)
uint64_t	newly	Quantity of a new pages added
uint64_t	prefault	Number of prefault write operations (not a pages)
uint64_t	spill	Quantity of spilled dirty pages
uint64_t	split	Page splits
uint64_t	unspill	Quantity of unspilled/reloaded pages
uint64_t	wops	Number of explicit write operations (not a pages) to a disk

◆ MDBX_commit_latency.gc_prof

struct MDBX_commit_latency.gc_prof

Информация для профилирования работы GC.

Note: Статистика является общей для всех процессов работающих с одним файлом БД и хранится в LCK-файле. Данные аккумулируются при фиксации всех транзакций, но только в сборках libmdbx c установленной опцией MDBX_ENABLE_PROFGC. Собранная статистика возвращаются любому процессу при использовании mdbx_txn_commit_ex() и одновременно обнуляется при завершении транзакций верхнего уровня (не вложенных).

Class Members
uint32_t	coalescences	Количество итераций слияния записей GC.
uint32_t	flushes	Количество принудительных фиксаций на диск во избежания приращения БД при работе вне режима MDBX_UTTERLY_NOSYNC.
uint32_t	kicks	Количество обращений к механизму Handle-Slow-Readers во избежания приращения БД. See also MDBX_hsr_func
uint32_t	self_counter	Счетчик выполнения по медленному пути (slow path execution count) GC для целей поддержки и обновления самой GC.
uint32_t	self_majflt	Количество страничных промахов (page faults) внутри GC при выделении и подготовки страниц для самой GC.
uint32_t	self_rsteps	Количество итераций поиска внутри GC при выделении страниц для целей поддержки и обновления самой GC.
uint32_t	self_rtime_monotonic	Время "по настенным часам" затраченное на чтение и поиск внутри GC для целей поддержки и обновления самой GC.
uint32_t	self_xpages	Количество запросов на выделение последовательностей страниц для самой GC.
uint32_t	self_xtime_cpu	Время ЦПУ в режиме пользователе затраченное на подготовку страниц извлекаемых из GC для целей поддержки и обновления самой GC, включая подкачку с диска.
uint32_t	wipes	Количество уничтожений предыдущих надежных/устойчивых точек фиксации при работе в режиме MDBX_UTTERLY_NOSYNC.
uint32_t	wloops	Количество итераций обновления GC, больше 1 если были повторы/перезапуски.
uint32_t	work_counter	Счетчик выполнения по медленному пути (slow path execution count) GC ради данных пользователя.
uint32_t	work_majflt	Количество страничных промахов (page faults) внутри GC при выделении и подготовки страниц для данных пользователя.
uint32_t	work_rsteps	Количество итераций поиска внутри GC при выделении страниц ради данных пользователя.
uint32_t	work_rtime_monotonic	Время "по настенным часам" затраченное на чтение и поиск внутри GC ради данных пользователя.
uint32_t	work_xpages	Количество запросов на выделение последовательностей страниц ради данных пользователя.
uint32_t	work_xtime_cpu	Время ЦПУ в режиме пользователе затраченное на подготовку страниц извлекаемых из GC для данных пользователя, включая подкачку с диска.

Macro Definition Documentation

◆ LIBMDBX_API

#define LIBMDBX_API

◆ LIBMDBX_API_TYPE

#define LIBMDBX_API_TYPE

◆ LIBMDBX_VERINFO_API

#define LIBMDBX_VERINFO_API __dll_export

◆ MDBX_DATANAME

#define MDBX_DATANAME "/mdbx.dat"

The name of the data file in the environment without using MDBX_NOSUBDIR.

◆ MDBX_LOCK_SUFFIX

#define MDBX_LOCK_SUFFIX "-lck"

The suffix of the lock file when MDBX_NOSUBDIR is used.

◆ MDBX_LOCKNAME

#define MDBX_LOCKNAME "/mdbx.lck"

The name of the lock file in the environment without using MDBX_NOSUBDIR.

◆ MDBX_MAP_RESIZED

#define MDBX_MAP_RESIZED MDBX_MAP_RESIZED_is_deprecated()

◆ MDBX_VERSION_MAJOR

#define MDBX_VERSION_MAJOR 0

◆ MDBX_VERSION_MINOR

#define MDBX_VERSION_MINOR 12

Typedef Documentation

◆ MDBX_env

typedef struct MDBX_env MDBX_env

Opaque structure for a database environment.

An environment supports multiple key-value sub-databases (aka key-value spaces or tables), all residing in the same shared-memory map.

See also: mdbx_env_create(); mdbx_env_close()

◆ mdbx_filehandle_t

typedef int mdbx_filehandle_t

◆ mdbx_mode_t

typedef mode_t mdbx_mode_t

◆ mdbx_pid_t

typedef pid_t mdbx_pid_t

◆ MDBX_preserve_func

typedef int(* MDBX_preserve_func) (void *context, MDBX_val *target, const void *src, size_t bytes)

◆ mdbx_tid_t

typedef pthread_t mdbx_tid_t

◆ MDBX_txn_flags_t

typedef enum MDBX_txn_flags_t MDBX_txn_flags_t

◆ MDBX_val

typedef struct iovec MDBX_val

Generic structure used for passing keys and data in and out of the database. .

See also: mdbx::slice; mdbx::buffer

Values returned from the database are valid only until a subsequent update operation, or the end of the transaction. Do not modify or free them, they commonly point into the database itself.

Key sizes must be between 0 and mdbx_env_get_maxkeysize() inclusive. The same applies to data sizes in databases with the MDBX_DUPSORT flag. Other data items can in theory be from 0 to MDBX_MAXDATASIZE bytes long.

Note: The notable difference between MDBX and LMDB is that MDBX support zero length keys.

◆ MDBX_warmup_flags_t

typedef enum MDBX_warmup_flags_t MDBX_warmup_flags_t

Enumeration Type Documentation

◆ MDBX_constants

enum MDBX_constants

Enumerator
MDBX_MAX_DBI	The hard limit for DBI handles
MDBX_MAXDATASIZE	The maximum size of a data item.
MDBX_MIN_PAGESIZE	The minimal database page size in bytes.
MDBX_MAX_PAGESIZE	The maximal database page size in bytes.

Function Documentation

◆ mdbx_dbi_open2()

LIBMDBX_API int mdbx_dbi_open2	(	MDBX_txn *	txn,
		const MDBX_val *	name,
		MDBX_db_flags_t	flags,
		MDBX_dbi *	dbi
	)

◆ mdbx_dbi_open_ex2()

MDBX_DEPRECATED LIBMDBX_API int mdbx_dbi_open_ex2	(	MDBX_txn *	txn,
		const MDBX_val *	name,
		MDBX_db_flags_t	flags,
		MDBX_dbi *	dbi,
		MDBX_cmp_func *	keycmp,
		MDBX_cmp_func *	datacmp
	)

◆ mdbx_env_copyW()

LIBMDBX_API int mdbx_env_copyW	(	MDBX_env *	env,
		const wchar_t *	dest,
		MDBX_copy_flags_t	flags
	)

Copy an MDBX environment to the specified path, with options.

This function may be used to make a backup of an existing environment. No lockfile is created, since it gets recreated at need.

Note: This call can trigger significant file size growth if run in parallel with write transactions, because it employs a read-only transaction. See long-lived transactions under Restrictions & Caveats section.; On Windows the mdbx_env_copyW() is recommended to use.

Parameters

[in]	env	An environment handle returned by mdbx_env_create(). It must have already been opened successfully.
[in]	dest	The pathname of a file in which the copy will reside. This file must not be already exist, but parent directory must be writable.
[in]	flags	Specifies options for this operation. This parameter must be bitwise OR'ing together any of the constants described here:

MDBX_CP_DEFAULTS Perform copy as-is without compaction, etc.
MDBX_CP_COMPACT Perform compaction while copying: omit free pages and sequentially renumber all pages in output. This option consumes little bit more CPU for processing, but may running quickly than the default, on account skipping free pages.
MDBX_CP_FORCE_DYNAMIC_SIZE Force to make resizable copy, i.e. dynamic size instead of fixed.

Returns: A non-zero error value on failure and 0 on success.

Note: Available only on Windows.

See also: mdbx_env_copy()

◆ mdbx_env_deleteW()

LIBMDBX_API int mdbx_env_deleteW	(	const wchar_t *	pathname,
		MDBX_env_delete_mode_t	mode
	)

Delete the environment's files in a proper and multiprocess-safe way.

Note: On Windows the mdbx_env_deleteW() is recommended to use.

Parameters

[in]	pathname	The pathname for the database or the directory in which the database files reside.
[in]	mode	Specifies deletion mode for the environment. This parameter must be set to one of the constants described above in the MDBX_env_delete_mode_t section.

Note: The MDBX_ENV_JUST_DELETE don't supported on Windows since system unable to delete a memory-mapped files.

Returns: A non-zero error value on failure and 0 on success, some possible errors are:

Return values

MDBX_RESULT_TRUE No corresponding files or directories were found, so no deletion was performed.

Note: Available only on Windows.

See also: mdbx_env_delete()

◆ mdbx_env_get_hsr()

LIBMDBX_API MDBX_hsr_func* mdbx_env_get_hsr ( const MDBX_env * env )

Gets current Handle-Slow-Readers callback used to resolve database full/overflow issue due to a reader(s) which prevents the old data from being recycled.

See also: MDBX_hsr_func; mdbx_env_set_hsr(); Long-lived read transactions

Parameters

[in] env An environment handle returned by mdbx_env_create().

Returns: A MDBX_hsr_func function or NULL if disabled or something wrong.

◆ mdbx_env_get_pathW()

LIBMDBX_API int mdbx_env_get_pathW	(	const MDBX_env *	env,
		const wchar_t **	dest
	)

Return the path that was used in mdbx_env_open().

Note: On Windows the mdbx_env_get_pathW() is recommended to use.

Parameters

[in]	env	An environment handle returned by mdbx_env_create()
[out]	dest	Address of a string pointer to contain the path. This is the actual string in the environment, not a copy. It should not be altered in any way.

Returns: A non-zero error value on failure and 0 on success, some possible errors are:

Return values

MDBX_EINVAL An invalid parameter was specified.

Note: Available only on Windows.

See also: mdbx_env_get_path()

◆ mdbx_env_openW()

LIBMDBX_API int mdbx_env_openW	(	MDBX_env *	env,
		const wchar_t *	pathname,
		MDBX_env_flags_t	flags,
		mdbx_mode_t	mode
	)

Open an environment instance.

Indifferently this function will fails or not, the mdbx_env_close() must be called later to discard the MDBX_env handle and release associated resources.

Note: On Windows the mdbx_env_openW() is recommended to use.

Parameters

[in]	env	An environment handle returned by mdbx_env_create()
[in]	pathname	The pathname for the database or the directory in which the database files reside. In the case of directory it must already exist and be writable.
[in]	flags	Specifies options for this environment. This parameter must be bitwise OR'ing together any constants described above in the env_flags and SYNC MODES sections.

Flags set by mdbx_env_set_flags() are also used:

MDBX_ENV_DEFAULTS, MDBX_NOSUBDIR, MDBX_RDONLY, MDBX_EXCLUSIVE, MDBX_WRITEMAP, MDBX_NOTLS, MDBX_NORDAHEAD, MDBX_NOMEMINIT, MDBX_COALESCE, MDBX_LIFORECLAIM. See env_flags section.
MDBX_SYNC_DURABLE, MDBX_NOMETASYNC, MDBX_SAFE_NOSYNC, MDBX_UTTERLY_NOSYNC. See SYNC MODES section.

Note: MDB_NOLOCK flag don't supported by MDBX, try use MDBX_EXCLUSIVE as a replacement.; MDBX don't allow to mix processes with different MDBX_SAFE_NOSYNC flags on the same environment. In such case MDBX_INCOMPATIBLE will be returned.

If the database is already exist and parameters specified early by mdbx_env_set_geometry() are incompatible (i.e. for instance, different page size) then mdbx_env_open() will return MDBX_INCOMPATIBLE error.

Parameters

[in] mode The UNIX permissions to set on created files. Zero value means to open existing, but do not create.

Returns: A non-zero error value on failure and 0 on success, some possible errors are:

Return values

MDBX_VERSION_MISMATCH	The version of the MDBX library doesn't match the version that created the database environment.
MDBX_INVALID	The environment file headers are corrupted.
MDBX_ENOENT	The directory specified by the path parameter doesn't exist.
MDBX_EACCES	The user didn't have permission to access the environment files.
MDBX_EAGAIN	The environment was locked by another process.
MDBX_BUSY	The MDBX_EXCLUSIVE flag was specified and the environment is in use by another process, or the current process tries to open environment more than once.
MDBX_INCOMPATIBLE	Environment is already opened by another process, but with different set of MDBX_SAFE_NOSYNC, MDBX_UTTERLY_NOSYNC flags. Or if the database is already exist and parameters specified early by mdbx_env_set_geometry() are incompatible (i.e. different pagesize, etc).
MDBX_WANNA_RECOVERY	The MDBX_RDONLY flag was specified but read-write access is required to rollback inconsistent state after a system crash.
MDBX_TOO_LARGE	Database is too large for this process, i.e. 32-bit process tries to open >4Gb database.

Note: Available only on Windows.

See also: mdbx_env_open()

◆ mdbx_liberr2str()

LIBMDBX_API const char* mdbx_liberr2str ( int errnum )

◆ mdbx_replace_ex()

LIBMDBX_API int mdbx_replace_ex	(	MDBX_txn *	txn,
		MDBX_dbi	dbi,
		const MDBX_val *	key,
		MDBX_val *	new_data,
		MDBX_val *	old_data,
		MDBX_put_flags_t	flags,
		MDBX_preserve_func	preserver,
		void *	preserver_context
	)

Variable Documentation

◆ mdbx_build

LIBMDBX_VERINFO_API const struct MDBX_build_info mdbx_build

libmdbx build information

◆ mdbx_version

LIBMDBX_VERINFO_API const struct MDBX_version_info mdbx_version

libmdbx version information

Modules

Classes

Macros

Typedefs

Enumerations

Functions

Variables

Detailed Description

Class Documentation

◆ MDBX_version_info

◆ MDBX_build_info

◆ MDBX_stat

◆ MDBX_envinfo

◆ MDBX_txn_info

◆ MDBX_commit_latency

◆ MDBX_canary

◆ MDBX_version_info.git

◆ MDBX_envinfo.mi_geo

◆ MDBX_envinfo.mi_bootid

◆ MDBX_envinfo.mi_bootid.current

◆ MDBX_envinfo.mi_bootid.meta0

◆ MDBX_envinfo.mi_bootid.meta1

◆ MDBX_envinfo.mi_bootid.meta2

◆ MDBX_envinfo.mi_pgop_stat

◆ MDBX_commit_latency.gc_prof

Macro Definition Documentation

◆ LIBMDBX_API

◆ LIBMDBX_API_TYPE

◆ LIBMDBX_VERINFO_API

◆ MDBX_DATANAME

◆ MDBX_LOCK_SUFFIX

◆ MDBX_LOCKNAME

◆ MDBX_MAP_RESIZED

◆ MDBX_VERSION_MAJOR

◆ MDBX_VERSION_MINOR

Typedef Documentation

◆ MDBX_env

◆ mdbx_filehandle_t

◆ mdbx_mode_t

◆ mdbx_pid_t

◆ MDBX_preserve_func

◆ mdbx_tid_t

◆ MDBX_txn_flags_t

◆ MDBX_val

◆ MDBX_warmup_flags_t

Enumeration Type Documentation

◆ MDBX_constants

Function Documentation

◆ mdbx_dbi_open2()

◆ mdbx_dbi_open_ex2()

◆ mdbx_env_copyW()

◆ mdbx_env_deleteW()

◆ mdbx_env_get_hsr()

◆ mdbx_env_get_pathW()

◆ mdbx_env_openW()

◆ mdbx_liberr2str()

◆ mdbx_replace_ex()

Variable Documentation

◆ mdbx_build

◆ mdbx_version