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The libmdbx C++ API header file. More...

• #include <algorithm>
• #include <cassert>
• #include <climits>
• #include <cstdint>
• #include <cstring>
• #include <exception>
• #include <ostream>
• #include <sstream>
• #include <stdexcept>
• #include <string>
• #include <type_traits>
• #include <utility>
• #include <vector>
• #include "mdbx.h"

Namespaces

Type	Name
namespace	mdbx The libmdbx C++ API namespace.
namespace	allocation_aware_details
namespace	std STL namespace.

Classes

Type	Name
struct	bad_map_id Thrown on MDBX_BAD_DBI , i.e. an invalid table handle was used.
struct	bad_transaction Thrown on MDBX_BAD_TXN , i.e. a transaction handle is invalid or was used after being finished.
struct	bad_value_size Thrown on MDBX_BAD_VALSIZE , i.e. an unsupported size of a key or a data item.
class	buffer <class ALLOCATOR, typename CAPACITY_POLICY> The chunk of data stored inside the buffer or located outside it.
struct	capacity_holder
struct	inplace_flag_holder
struct	stub_allocated_holder
struct	buffer_pair_spec <typename ALLOCATOR, typename CAPACITY_POLICY> A pair of buffer instances for a key and a value, with the same allocator and capacity policy; the buffer counterpart ofpair .
struct	buffer_tag Type tag for delivered buffer template classes.
class	cache_entry Cache entry for the transparent read-your-writes caching, see txn::get_cached() andmdbx_cache_get() .
class	cursor Unmanaged cursor.
struct	estimate_result The result of a range estimation: the boundary key-value pair plus the approximate number of items.
struct	move_result The result of a cursor move/seek operation: the found key-value pair plus the success flag.
class	cursor_managed Managed cursor.
struct	dangling_map_id Thrown on MDBX_DANGLING_DBI , i.e. a table handle refers to a non-existent table.
struct	db_corrupted Thrown on MDBX_CORRUPTED , i.e. the database is corrupted or an invalid data was detected.
struct	db_full Thrown on MDBX_MAP_FULL , i.e. the database is full and the environment cannot be extended.
struct	db_invalid Thrown on MDBX_INVALID , i.e. an invalid parameter was specified or the environment is already closed.
struct	db_too_large Thrown on MDBX_TOO_LARGE , i.e. the database is too large for the current process/environment.
struct	db_unable_extend Thrown on MDBX_UNABLE_EXTEND_MAPSIZE , i.e. the requested geometry change needs the mapping to be re-created but it could not be applied right now.
struct	db_version_mismatch Thrown on MDBX_VERSION_MISMATCH , i.e. the database was created by an incompatible version of libmdbx.
struct	db_wanna_write_for_recovery Thrown on MDBX_WANNA_RECOVERY , i.e. the database requires recovery usingmdbx_chk and/ormdbx_env_open_for_recovery() .
struct	default_capacity_policy The default capacity policy for the buffer class: rounds the allocated capacity and advises whether to grow, keep or shrink it.
struct	duplicated_lck_file Thrown on MDBX_DUPLICATED_LCK , i.e. the lock file was created in a manner that conflicts with the current process' state.
class	env Unmanaged database environment.
struct	geometry Database geometry for size management.
struct	size Tagged type for output to std::ostream.
struct	limits A namespace-like holder of static functions returning the various libmdbx limits, the C++ counterpart of the mdbx_limits_*() C API.
struct	operate_options Operate options.
struct	operate_parameters Operate parameters.
struct	reader_info Reader information.
struct	reclaiming_options Garbage reclaiming options.
struct	sysraminfo Information about the system RAM, see mdbx_get_sysraminfo() .
class	env_managed Managed database environment.
struct	create_parameters Additional parameters for creating a new database.
class	error Implements error information and throwing corresponding exceptions.
class	exception Base class for all libmdbx's exceptions that correspond to libmdbx errors.
class	exception_thunk Transfers C++ exceptions thru C callbacks.
class	fatal Fatal exception that leads to termination anyway in dangerous unrecoverable cases.
struct	from_base58 Base58 decoder which satisfySliceTranscoder concept.
struct	from_base64 Base64 decoder which satisfySliceTranscoder concept.
struct	from_hex Hexadecimal decoder which satisfy SliceTranscoder concept.
struct	incompatible_operation Thrown on MDBX_INCOMPATIBLE , i.e. an operation is incompatible with the environment/table options.
struct	internal_page_full Thrown on MDBX_PAGE_FULL , i.e. an item does not fit into a page of the table.
struct	internal_problem Thrown on MDBX_PROBLEM , i.e. an unexpected internal problem was detected.
struct	key_exists Thrown on MDBX_KEYEXIST , i.e. the key/data pair already exists and_MDBX_NOOVERWRITE _was specified.
struct	key_mismatch Thrown on MDBX_EKEYMISMATCH , i.e. an insert with the append hint but the key is not the last one.
struct	laggard_reader Thrown on MDBX_LAGGARD_READER , i.e. the reader is lagging too much behind.
struct	map_handle A handle for an individual table (aka key-value space, maps or sub-database) in the environment.
struct	info Flags and state of a table (aka map).
struct	max_maps_reached Thrown on MDBX_DBS_FULL , i.e. the maximum number of table handles has been reached.
struct	max_readers_reached Thrown on MDBX_READERS_FULL , i.e. the environment's reader table is full.
struct	multivalue Thrown on MDBX_EMULTIVAL , i.e. the operation is not supported for the multi-value (dupsort) key.
struct	mvcc_retarded Thrown on MDBX_MVCC_RETARDED , i.e. the MVCC snapshot is retarded too much to continue.
struct	no_data Thrown on MDBX_ENODATA , i.e. the requested data is missing.
struct	not_found Thrown on MDBX_NOTFOUND , i.e. the requested key/data pair was not found.
struct	operation_not_permitted Thrown on MDBX_EPERM , i.e. the operation is not permitted in the current state/environment mode.
struct	pair Combines pair of slices for key and value to represent result of certain operations.
struct	pair_result Combines pair of slices for key and value with boolean flag to represent result of certain operations.
struct	permission_denied_or_not_writeable Thrown on MDBX_EACCESS , i.e. a permission was denied or the environment/data is not writable.
struct	reader_slot_busy Thrown on MDBX_BAD_RSLOT , i.e. a reader slot is invalid or busy.
struct	remote_media Thrown on MDBX_EREMOTE , i.e. a file/locking system call failed for the reason that could not be diagnosed.
struct	slice References a data located outside the slice.
struct	something_busy Thrown on MDBX_BUSY , i.e. some resource is busy by another thread or process.
struct	thread_mismatch Thrown on MDBX_THREAD_MISMATCH , i.e. the transaction/cursor is used by an alien thread.
struct	to_base58 Base58 encoder which satisfySliceTranscoder concept.
struct	to_base64 Base64 encoder which satisfySliceTranscoder concept.
struct	to_hex Hexadecimal encoder which satisfy SliceTranscoder concept.
struct	transaction_full Thrown on MDBX_TXN_FULL , i.e. the transaction has too many dirty pages and cannot be continued.
struct	transaction_ousted Thrown on MDBX_OUSTED , i.e. the current write transaction was ousted by a newer one.
struct	transaction_overlapping Thrown on MDBX_TXN_OVERLAPPING , i.e. a write transaction was started while another one is in progress by the same process.
class	txn Unmanaged database transaction.
class	txn_managed Managed database transaction.
struct	value_result Combines data slice with boolean flag to represent result of certain operations.
struct	hash<::mdbx::buffer< ALLOCATOR, CAPACITY_POLICY > > <class ALLOCATOR, typename CAPACITY_POLICY>
struct	hash<::mdbx::cursor > <>
struct	hash<::mdbx::env > <>
struct	hash<::mdbx::map_handle > <>
struct	hash<::mdbx::slice > <>
struct	hash<::mdbx::txn > <>

Public Types

Type	Name
union	bin

Macros

Type	Name
define	MDBX_ASSERT_CXX20_CONCEPT_SATISFIED (CONCEPT, TYPE) static\_assert(CONCEPT<TYPE>)
define	MDBX_CONSTEXPR_ASSERT (expr) ((expr) ? void(0) : [] { assert(!#expr); }())
define	MDBX_CXX01_CONSTEXPR_ENUM [**MDBX\_CXX01\_CONSTEXPR**](group__api__macros.md#define-mdbx_cxx01_constexpr)
define	MDBX_CXX11_CONSTEXPR_ENUM [**MDBX\_CXX11\_CONSTEXPR**](group__api__macros.md#define-mdbx_cxx11_constexpr)
define	MDBX_CXX14_CONSTEXPR_ENUM [**MDBX\_CXX14\_CONSTEXPR**](group__api__macros.md#define-mdbx_cxx14_constexpr)
define	MDBX_CXX17_CONSTEXPR constexpr
define	MDBX_CXX17_CONSTEXPR_ENUM [**MDBX\_CXX17\_CONSTEXPR**](mdbx_8h_09_09.md#define-mdbx_cxx17_constexpr)
define	MDBX_CXX17_FALLTHROUGH [[fallthrough]]
define	MDBX_CXX20_CONSTEXPR constexpr
define	MDBX_CXX20_CONSTEXPR_ENUM [**MDBX\_CXX20\_CONSTEXPR**](mdbx_8h_09_09.md#define-mdbx_cxx20_constexpr)
define	MDBX_CXX20_LIKELY [[likely]]
define	MDBX_EXTERN_API_TEMPLATE (API_ATTRIBUTES, ...) extern template class API\_ATTRIBUTES \_\_VA\_ARGS\_\_
define	MDBX_IF_CONSTEXPR constexpr
define	MDBX_INSTALL_API_TEMPLATE (API_ATTRIBUTES, ...) template class \_\_VA\_ARGS\_\_
define	MDBX_MSVC_DECLSPEC_EMPTY_BASES
define	MDBX_NODISCARD [[nodiscard]]
define	MDBX_USING_CXX_EXPERIMENTAL_FILESYSTEM 0

Detailed Description

This file is part of the libmdbx amalgamated source code (v0.15.0-334-gb8f2dad5 at 2026-10-29T00:17:01+03:00).

libmdbx (aka MDBX) is an extremely fast, compact, powerful, embeddable, transactional key-value store, with Apache 2.0 license. MDBX has a specific set of properties and capabilities, focused on creating unique lightweight solutions with extraordinary performance.

Please visit https://libmdbx.dqdkfa.ru for more information, documentation, C++ API description and links to the origin git repo with the source code. Questions, feedback and suggestions are welcome to the Telegram' group https://t.me/libmdbx, MAX' chat https://max.ru/join/dKckvyuARxp1vRK-wnPur8zYCEkbR3OUOmpPWkWxp78.

Donations are welcome to ETH 0xD104d8f8B2dC312aaD74899F83EBf3EEBDC1EA3A, BTC bc1qzvl9uegf2ea6cwlytnanrscyv8snwsvrc0xfsu, SOL FTCTgbHajoLVZGr8aEFWMzx3NDMyS5wXJgfeMTmJznRi. Всё будет хорошо!

The libmdbx project has been completely relocated to the jurisdiction of the Russian Federation.

Note:

libmdbx is still open and provided with first-class free support.

Copyright:

SPDX-License-Identifier: Apache-2.0

Author:

Леонид Юрьев aka Leonid Yuriev leo@yuriev.ru

Date:

2020-2026

Public Types Documentation

union bin

---

Macro Definition Documentation

define MDBX_ASSERT_CXX20_CONCEPT_SATISFIED

#define MDBX_ASSERT_CXX20_CONCEPT_SATISFIED (
    CONCEPT,
    TYPE
) `static_assert(CONCEPT<TYPE>)`

---

define MDBX_CONSTEXPR_ASSERT

#define MDBX_CONSTEXPR_ASSERT (
    expr
) `((expr) ? void(0) : [] { assert(!#expr); }())`

Workaround for old compilers without support assertion inside constexpr functions.

---

define MDBX_CXX01_CONSTEXPR_ENUM

#define MDBX_CXX01_CONSTEXPR_ENUM `MDBX_CXX01_CONSTEXPR`

---

define MDBX_CXX11_CONSTEXPR_ENUM

#define MDBX_CXX11_CONSTEXPR_ENUM `MDBX_CXX11_CONSTEXPR`

---

define MDBX_CXX14_CONSTEXPR_ENUM

#define MDBX_CXX14_CONSTEXPR_ENUM `MDBX_CXX14_CONSTEXPR`

---

define MDBX_CXX17_CONSTEXPR

#define MDBX_CXX17_CONSTEXPR `constexpr`

Workaround for old compilers without properly support for C++17 constexpr

---

define MDBX_CXX17_CONSTEXPR_ENUM

#define MDBX_CXX17_CONSTEXPR_ENUM `MDBX_CXX17_CONSTEXPR`

---

define MDBX_CXX17_FALLTHROUGH

#define MDBX_CXX17_FALLTHROUGH `[[fallthrough]]`

---

define MDBX_CXX20_CONSTEXPR

#define MDBX_CXX20_CONSTEXPR `constexpr`

Workaround for old compilers without properly support for C++20 constexpr.

---

define MDBX_CXX20_CONSTEXPR_ENUM

#define MDBX_CXX20_CONSTEXPR_ENUM `MDBX_CXX20_CONSTEXPR`

---

define MDBX_CXX20_LIKELY

#define MDBX_CXX20_LIKELY `[[likely]]`

---

define MDBX_EXTERN_API_TEMPLATE

#define MDBX_EXTERN_API_TEMPLATE (
    API_ATTRIBUTES,
    ...
) `extern template class API_ATTRIBUTES __VA_ARGS__`

---

define MDBX_IF_CONSTEXPR

#define MDBX_IF_CONSTEXPR `constexpr`

Workaround for old compilers without properly support for C++20 if constexpr.

---

define MDBX_INSTALL_API_TEMPLATE

#define MDBX_INSTALL_API_TEMPLATE (
    API_ATTRIBUTES,
    ...
) `template class __VA_ARGS__`

---

define MDBX_MSVC_DECLSPEC_EMPTY_BASES

#define MDBX_MSVC_DECLSPEC_EMPTY_BASES 

---

define MDBX_NODISCARD

#define MDBX_NODISCARD `[[nodiscard]]`

Workaround for old compilers without [[nodiscard]] support

---

define MDBX_USING_CXX_EXPERIMENTAL_FILESYSTEM

#define MDBX_USING_CXX_EXPERIMENTAL_FILESYSTEM `0`

---

---

The documentation for this class was generated from the following file mdbx.h++