C API

Topics
	Error handling
	Opening & Closing
	Transactions
	Tables
	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.
	Checking and Recovery

Classes
struct	MDBX_version_info
	libmdbx version information, More...
struct	MDBX_build_info
	libmdbx build information More...
struct	MDBX_stat
	Statistics for a table 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.meta
struct	MDBX_envinfo.mi_pgop_stat
struct	MDBX_envinfo.mi_dxbid
struct	MDBX_commit_latency.gc_prof
	Информация для профилирования работы GC. More...
struct	MDBX_commit_latency.gc_prof.pnl_merge_work
struct	MDBX_commit_latency.gc_prof.pnl_merge_self

Macros
#define	MDBX_VERSION_UNSTABLE
#define	MDBX_VERSION_MAJOR   0
#define	MDBX_VERSION_MINOR   14
#define	LIBMDBX_API   __dll_export
#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.
#define	MDBX_DATANAME   "/mdbx.dat"
	The name of the data file in the environment without using MDBX_NOSUBDIR.
#define	MDBX_LOCK_SUFFIX   "-lck"
	The suffix of the lock file when MDBX_NOSUBDIR is used.
#define	MDBX_MAP_RESIZED   MDBX_MAP_RESIZED_is_deprecated()
#define	mdbx_env_openT(env, pathname, flags, mode)
#define	mdbx_env_deleteT(pathname, mode)
#define	mdbx_env_copyT(env, dest, flags)
#define	mdbx_txn_copy2pathnameT(txn, dest, flags)
#define	mdbx_env_get_pathT(env, dest)

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

Variables
LIBMDBX_VERINFO_API const struct MDBX_version_info	mdbx_version
	libmdbx version information
LIBMDBX_VERINFO_API const struct MDBX_build_info	mdbx_build
	libmdbx build information

Detailed Description

---

Class Documentation

MDBX_version_info

struct MDBX_version_info

libmdbx version information,

See also

https://semver.org/

Class Members
struct MDBX_version_info.git	git	source information from git
uint16_t	major	Major version number
uint16_t	minor	Minor version number
uint16_t	patch	Patch number
const char *	semver_prerelease	Semantic Versioning pre-release
const char *	sourcery	sourcery anchor for pinning
uint16_t	tweak	Tweak number

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 *	metadata	an extra/custom information provided via the MDBX_BUILD_METADATA definition during library build
const char *	options	mdbx-related options
const char *	target	cpu/arch-system-config triplet

MDBX_stat

struct MDBX_stat

Statistics for a table 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 large/overflow pages
uint32_t	ms_psize	Size of a table page. This is the same for all tables in a database.

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	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_dxbid	mi_dxbid
struct MDBX_envinfo.mi_geo	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_meta_sign[3]
uint64_t	mi_meta_txnid[3]
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	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	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 table's 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_put()

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
struct MDBX_envinfo.mi_bootid.current	current
struct MDBX_envinfo.mi_bootid.meta	meta[3]

MDBX_envinfo.mi_bootid.current

struct MDBX_envinfo.mi_bootid.current

Class Members
uint64_t	x
uint64_t	y

MDBX_envinfo.mi_bootid.meta

struct MDBX_envinfo.mi_bootid.meta

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_envinfo.mi_dxbid

struct MDBX_envinfo.mi_dxbid

Class Members
uint64_t	x
uint64_t	y

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
struct MDBX_commit_latency.gc_prof.pnl_merge_self	pnl_merge_self
struct MDBX_commit_latency.gc_prof.pnl_merge_work	pnl_merge_work
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.

MDBX_commit_latency.gc_prof.pnl_merge_work

struct MDBX_commit_latency.gc_prof.pnl_merge_work

Class Members
uint32_t	calls
uint32_t	time
uint64_t	volume

MDBX_commit_latency.gc_prof.pnl_merge_self

struct MDBX_commit_latency.gc_prof.pnl_merge_self

Class Members
uint32_t	calls
uint32_t	time
uint64_t	volume

Macro Definition Documentation

LIBMDBX_API

#define LIBMDBX_API   __dll_export

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_env_copyT

#define mdbx_env_copyT	(		env,
			dest,
			flags )

Value:

mdbx_env_copyW(env, dest, flags)

mdbx_env_deleteT

#define mdbx_env_deleteT	(		pathname,
			mode )

Value:

mdbx_env_deleteW(pathname, mode)

mdbx_env_get_pathT

#define mdbx_env_get_pathT	(		env,
			dest )

Value:

mdbx_env_get_pathW(env, dest)

mdbx_env_openT

#define mdbx_env_openT	(		env,
			pathname,
			flags,
			mode )

Value:

mdbx_env_openW(env, pathname, flags, mode)

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_txn_copy2pathnameT

#define mdbx_txn_copy2pathnameT	(		txn,
			dest,
			flags )

Value:

mdbx_txn_copy2pathnameW(txn, dest, path)

MDBX_VERSION_MAJOR

#define MDBX_VERSION_MAJOR   0

MDBX_VERSION_MINOR

#define MDBX_VERSION_MINOR   14

MDBX_VERSION_UNSTABLE

#define MDBX_VERSION_UNSTABLE

Typedef Documentation

MDBX_env

typedef struct MDBX_env MDBX_env

Opaque structure for a database environment.

An environment supports multiple key-value tables (aka key-value maps, spaces or sub-databases), 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_val

typedef struct iovec MDBX_val

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

See also

mdbx::slice

mdbx::buffer

Values returned from the table 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 tables 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.

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_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()

mdbx_txn_park()

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_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_NOSTICKYTHREADS, 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_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