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ChangeLog

English version by Google and by Yandex.

В разработке v0.12.2

Новое:

  • Отключение учета «грязных» страниц в не требующих этого режимах (MDBX_WRITEMAP при MDBX_AVOID_MSYNC=0). Доработка позволяет снизить накладные расходы и была запланирована давно, но откладывалась так как требовала других изменений.

  • Вытеснение из памяти (спиллинг) «грязных» страниц с учетом размера large/overflow-страниц. Доработка позволяет корректно соблюдать политику задаваемую опциями MDBX_opt_txn_dp_limit, MDBX_opt_spill_max_denominator, MDBX_opt_spill_min_denominator и была запланирована давно, но откладывалась так как требовала других изменений.

  • Для Windows в API добавлены UNICODE-зависимые определения макросов MDBX_DATANAME, MDBX_LOCKNAME и MDBX_LOCK_SUFFIX.

  • Переход на преимущественное использование типа size_t для уменьшения накладных расходов на платформе Эльбрус.

  • В API добавлены функции mdbx_limits_valsize4page_max() и mdbx_env_get_valsize4page_max() возвращающие максимальный размер в байтах значения, которое может быть размещена в одной large/overflow-странице, а не последовательности из двух или более таких страниц. Для таблиц с поддержкой дубликатов вынос значений на large/overflow-страницы не поддерживается, поэтому результат совпадает с mdbx_limits_valsize_max().

  • В API добавлены функции mdbx_limits_pairsize4page_max()и mdbx_env_get_pairsize4page_max() возвращающие в байтах максимальный суммарный размер пары ключ-значение для их размещения на одной листовой страницы, без выноса значения на отдельную large/overflow-страницу. Для таблиц с поддержкой дубликатов вынос значений на large/overflow-страницы не поддерживается, поэтому результат определяет максимальный/допустимый суммарный размер пары ключ-значение.

  • Реализовано использование асинхронной (overlapped) записи в Windows, включая использования небуфферизированного ввода-вывода и WriteGather(). Это позволяет сократить накладные расходы и частично обойти проблемы Windows с низкой производительностью ввода-вывода, включая большие задержки FlushFileBuffers(). Новый код также обеспечивает консолидацию записываемых регионов на всех платформах, а на Windows использование событий (events) сведено к минимум, одновременно с автоматических использованием WriteGather(). Поэтому ожидается существенное снижение накладных расходов взаимодействия с ОС, а в Windows это ускорение, в некоторых сценариях, может быть кратным в сравнении с LMDB.

  • Добавлена опция сборки MDBX_AVOID_MSYNC, которая определяет поведение libmdbx в режиме MDBX_WRITE_MAP (когда данные изменяются непосредственно в отображенных в ОЗУ страницах БД):

    • Если MDBX_AVOID_MSYNC=0 (по умолчанию на всех системах кроме Windows), то (как прежде) сохранение данных выполняется посредством msync(), либо FlushViewOfFile() на Windows. На платформах с полноценной подсистемой виртуальной памяти и адекватным файловым вводом-выводом это обеспечивает минимум накладных расходов (один системный вызов) и максимальную производительность. Однако, на Windows приводит к значительной деградации, в том числе из-за того что после FlushViewOfFile() требуется также вызов FlushFileBuffers() с массой проблем и суеты внутри ядра ОС.

    • Если MDBX_AVOID_MSYNC=1 (по умолчанию только на Windows), то сохранение данных выполняется явной записью в файл каждой измененной страницы БД. Это требует дополнительных накладных расходов, как на отслеживание измененных страниц (ведение списков "грязных" страниц), так и на системные вызовы для их записи. Кроме этого, с точки зрения подсистемы виртуальной памяти ядра ОС, страницы БД измененные в ОЗУ и явно записанные в файл, могут либо оставаться "грязными" и быть повторно записаны ядром ОС позже, либо требовать дополнительных накладных расходов для отслеживания PTE (Page Table Entries), их модификации и дополнительного копирования данных. Тем не менее, по имеющейся информации, на Windows такой путь записи данных в целом обеспечивает более высокую производительность.

  • Улучшение эвристики включения авто-слияния записей GC.

  • Изменение формата LCK и семантики некоторых внутренних полей. Версии libmdbx использующие разный формат не смогут работать с одной БД одновременно, а только поочередно (LCK-файл переписывается при открытии первым открывающим БД процессом).

  • В C++ API добавлены методы фиксации транзакции с получением информации о задержках.

  • Added MDBX_HAVE_BUILT IN_CPU_SUPPORTS build option to control use GCC's __builtin_cpu_supports() function, which could be unavailable on a fake OSes (macos, ios, android, etc).

Исправления:

  • Больше контроля и осторожности (паранойи) для страховки от дефектов mremap().
  • Костыль для починки сборки со старыми версиями stdatomic.h из GNU Lib C, где макросы ATOMIC_*_LOCK_FREE ошибочно переопределяются через функции.
  • Использование fcntl64(F_GETLK64/F_SETLK64/F_SETLKW64) при наличии. Это решает проблему срабатывания проверочного утверждения при сборке для платформ где тип off_t шире соответствующих полей структуры flock, используемой для блокировки файлов.
  • Доработан сбор информации о задержках при фиксации транзакций:
    • Устранено искажение замеров длительности обновления GC при включении отладочного внутреннего аудита;
    • Защита от undeflow-нуля только общей задержки в метриках, чтобы исключить ситуации, когда сумма отдельных стадий больше общей длительности.
  • Ряд исправлений для устранения срабатываний проверочных утверждения в отладочных сборках.
  • Более осторожное преобразование к типу mdbx_tid_t для устранения предупреждений.
  • Исправление лишнего сброса данных на диск в режиме MDBX_SAFE_NOSYNC при обновлении GC.
  • Fixed an extra check for MDBX_APPENDDUP inside mdbx_cursor_put() which could result in returning MDBX_EKEYMISMATCH for valid cases.
  • Fixed nasty clz() bug (by using _BitScanReverse(), only MSVC builds affected).

Мелочи:

  • Проверка атомарности C11-операций c 32/64-битными данными.
  • Уменьшение в 42 раза значения по-умолчанию для me_options.dp_limit в отладочных сборках.
  • Добавление платформы gcc-riscv64-linux-gnu в список для цели cross-gcc.
  • Небольшие правки скрипта long_stochastic.sh для работы в Windows.
  • Удаление ненужного вызова LockFileEx() внутри mdbx_env_copy().
  • Добавлено описание использования файловых дескрипторов в различных режимах.
  • Добавлено использование _CrtDbgReport() в отладочных сборках.
  • Fixed an extra ensure/assertion check of oldest_reader inside txn_end().
  • Removed description of deprecated usage of MDBX_NODUPDATA.
  • Fixed regression ASAN/Valgring-enabled builds.
  • Fixed minor MingGW warning.

v0.12.1 (Positive Proxima) at 2022-08-24

The planned frontward release with new superior features on the day of 20 anniversary of Positive Technologies.

37 files changed, 7604 insertions(+), 7417 deletions(-)
Signed-off-by: Леонид Юрьев (Leonid Yuriev) <leo@yuriev.ru>

New:

  • The Big Foot feature which significantly reduces GC overhead for processing large lists of retired pages from huge transactions. Now libmdbx avoid creating large chunks of PNLs (page number lists) which required a long sequences of free pages, aka large/overflow pages. Thus avoiding searching, allocating and storing such sequences inside GC.
  • Improved hot/online validation and checking of database pages both for more robustness and performance.
  • New solid and fast method to latch meta-pages called Troika. The minimum of memory barriers, reads, comparisons and conditional transitions are used.
  • New MDBX_VALIDATION environment options to extra validation of DB structure and pages content for carefully/safe handling damaged or untrusted DB.
  • Accelerated ×16/×8/×4 by AVX512/AVX2/SSE2/Neon implementations of search page sequences.
  • Added the gcrtime_seconds16dot16 counter to the "Page Operation Statistics" that accumulates time spent for GC searching and reclaiming.
  • Copy-with-compactification now clears/zeroes unused gaps inside database pages.
  • The C and C++ APIs has been extended and/or refined to simplify using wchar_t pathnames. On Windows the mdbx_env_openW(), ``mdbx_env_get_pathW()(), mdbx_env_copyW(), mdbx_env_open_for_recoveryW() are available for now, but the mdbx_env_get_path() has been replaced in favor of mdbx_env_get_pathW().
  • Added explicit error message for Buildroot's Microblaze toolchain maintainers.
  • Added MDBX_MANAGE_BUILD_FLAGS build options for CMake.
  • Speed-up internal bsearch/lower_bound implementation using branchless tactic, including workaround for CLANG x86 optimiser bug.
  • A lot internal refinement and micro-optimisations.
  • Internally counted volume of dirty pages (unused for now but for coming features).

Fixes:

  • Never use modern __cxa_thread_atexit() on Apple's OSes.
  • Don't check owner for finished transactions.
  • Fixed typo in MDBX_EINVAL which breaks MingGW builds with CLANG.

v0.12.0 at 2022-06-19

Not a release but preparation for changing feature set and API.

v0.11.10 (the TriColor) at 2022-08-22

The stable bugfix release. It is planned that this will be the last release of the v0.11 branch.

14 files changed, 263 insertions(+), 252 deletions(-)
Signed-off-by: Леонид Юрьев (Leonid Yuriev) <leo@yuriev.ru>

New:

  • The C++ API has been refined to simplify support for wchar_t in path names.
  • Added explicit error message for Buildroot's Microblaze toolchain maintainers.

Fixes:

  • Never use modern __cxa_thread_atexit() on Apple's OSes.
  • Use MultiByteToWideChar(CP_THREAD_ACP) instead of mbstowcs().
  • Don't check owner for finished transactions.
  • Fixed typo in MDBX_EINVAL which breaks MingGW builds with CLANG.

Minors:

  • Fixed variable name typo.
  • Using ldd to check used dso.
  • Added MDBX_WEAK_IMPORT_ATTRIBUTE macro.
  • Use current transaction geometry for untouched parameters when env_set_geometry() called within a write transaction.
  • Minor clarified iov_page() failure case.

v0.11.9 (Чирчик-1992) at 2022-08-02

The stable bugfix release.

18 files changed, 318 insertions(+), 178 deletions(-)
Signed-off-by: Леонид Юрьев (Leonid Yuriev) <leo@yuriev.ru>

Acknowledgements:

New:

  • Ability to customise MDBX_LOCK_SUFFIX, MDBX_DATANAME, MDBX_LOCKNAME just by predefine ones during build.
  • Added to mdbx::env_managed's methods a few overloads with const char* pathname parameter (C++ API).

Fixes:

  • Fixed hang copy-with-compactification of a corrupted DB or in case the volume of output pages is a multiple of MDBX_ENVCOPY_WRITEBUF.
  • Fixed standalone non-CMake build on MacOS (#include AvailabilityMacros.h>).
  • Fixed unexpected MDBX_PAGE_FULL error in rare cases with large database page sizes.

Minors:

  • Minor fixes Doxygen references, comments, descriptions, etc.
  • Fixed copy&paste typo inside meta_checktxnid().
  • Minor fix meta_checktxnid() to avoid assertion in debug mode.
  • Minor fix mdbx_env_set_geometry() to avoid returning EINVAL in particular rare cases.
  • Minor refine/fix batch-get testcase for large page size.
  • Added --pagesize NN option to long-stotastic test script.
  • Updated Valgrind-suppressions file for modern GCC.
  • Fixed has no symbols warning from Apple's ranlib.

v0.11.8 (Baked Apple) at 2022-06-12

The stable release with an important fixes and workaround for the critical macOS thread-local-storage issue.

Acknowledgements:

New:

  • Added most of transactions flags to the public API.
  • Added MDBX_NOSUCCESS_EMPTY_COMMIT build option to return non-success result (MDBX_RESULT_TRUE) on empty commit.
  • Reworked validation and import of DBI-handles into a transaction. Assumes these changes will be invisible to most users, but will cause fewer surprises in complex DBI cases.
  • Added ability to open DB in without-LCK (exclusive read-only) mode in case no permissions to create/write LCK-file.

Fixes:

  • A series of fixes and improvements for automatically generated documentation (Doxygen).
  • Fixed copy&paste bug with could lead to SIGSEGV (nullptr dereference) in the exclusive/no-lck mode.
  • Fixed minor warnings from modern Apple's CLANG 13.
  • Fixed minor warnings from CLANG 14 and in-development CLANG 15.
  • Fixed SIGSEGV regression in without-LCK (exclusive read-only) mode.
  • Fixed mdbx_check_fs_local() for CDROM case on Windows.
  • Fixed nasty typo of typename which caused false MDBX_CORRUPTED error in a rare execution path, when the size of the thread-ID type not equal to 8.
  • Fixed Elbrus/E2K LCC 1.26 compiler warnings (memory model for atomic operations, etc).
  • Fixed write-after-free memory corruption on latest macOS during finalization/cleanup of thread(s) that executed read transaction(s).

    The issue was suddenly discovered by a CI after adding an iteration with macOS 11 "Big Sur", and then reproduced on recent release of macOS 12 "Monterey". The issue was never noticed nor reported on macOS 10 "Catalina" nor others. Analysis shown that the problem caused by a change in the behavior of the system library (internals of dyld and pthread) during thread finalization/cleanup: now a memory allocated for a __thread variable(s) is released before execution of the registered Thread-Local-Storage destructor(s), thus a TLS-destructor will write-after-free just by legitime dereference any __thread variable. This is unexpected crazy-like behavior since the order of resources releasing/destroying is not the reverse of ones acquiring/construction order. Nonetheless such surprise is now workarounded by using atomic compare-and-swap operations on a 64-bit signatures/cookies.

Minors:

  • Refined release-assets GNU Make target.
  • Added logging to mdbx_fetch_sdb() to help debugging complex DBI-handels use cases.
  • Added explicit error message from probe of no-support for std::filesystem.
  • Added contributors "score" table by git fame to generated docs.
  • Added mdbx_assert_fail() to public API (mostly for backtracing).
  • Now C++20 concepts used/enabled only when __cpp_lib_concepts >= 202002.
  • Don't provide nor report package information if used as a CMake subproject.

v0.11.7 (Resurrected Sarmat) at 2022-04-22

The stable risen release after the Github's intentional malicious disaster.

We have migrated to a reliable trusted infrastructure

The origin for now is at GitFlic since on 2022-04-15 the Github administration, without any warning nor explanation, deleted libmdbx along with a lot of other projects, simultaneously blocking access for many developers. For the same reason Github is blacklisted forever.

GitFlic already support Russian and English languages, plan to support more, including 和 中文. You are welcome!

New:

  • Added the tools-static make target to build statically linked MDBX tools.
  • Support for Microsoft Visual Studio 2022.
  • Support build by MinGW' make from command line without CMake.
  • Added mdbx::filesystem C++ API namespace that corresponds to std::filesystem or std::experimental::filesystem.
  • Created website for online auto-generated documentation.
  • Used https://web.archive.org/web/20220414235959/https://github.com/erthink/ for dead (or temporarily lost) resources deleted by Github.
  • Added --loglevel= command-line option to the mdbx_test tool.
  • Added few fast smoke-like tests into CMake builds.

Fixes:

  • Fixed a race between starting a transaction and creating a DBI descriptor that could lead to SIGSEGV in the cursor tracking code.
  • Clarified description of MDBX_EPERM error returned from mdbx_env_set_geometry().
  • Fixed non-promoting the parent transaction to be dirty in case the undo of the geometry update failed during abortion of a nested transaction.
  • Resolved linking issues with libstdc++fs/libc++fs/libc++experimental for C++ std::filesystem or std::experimental::filesystem for legacy compilers.
  • Added workaround for GNU Make 3.81 and earlier.
  • Added workaround for Elbrus/LCC 1.25 compiler bug of class inline static constexpr member field.
  • Fixed minor assertion regression (only debug builds were affected).
  • Fixed detection of C++20 concepts accessibility.
  • Fixed detection of Clang's LTO availability for Android.
  • Fixed extra definition of _FILE_OFFSET_BITS=64 for Android that is problematic for 32-bit Bionic.
  • Fixed build for ARM/ARM64 by MSVC.
  • Fixed non-x86 Windows builds with MDBX_WITHOUT_MSVC_CRT=ON and MDBX_BUILD_SHARED_LIBRARY=ON.

Minors:

  • Resolve minor MSVC warnings: avoid /INCREMENTAL[:YES] with /LTCG, /W4 with /W3, the C5105 warning.
  • Switched to using MDBX_EPERM instead of MDBX_RESULT_TRUE to indicate that the geometry cannot be updated.
  • Added NULL checking during memory allocation inside mdbx_chk.
  • Resolved all warnings from MinGW while used without CMake.
  • Added inheretable target_include_directories() to CMakeLists.txt for easy integration.
  • Added build-time checks and paranoid runtime assertions for the off_t arguments of fcntl() which are used for locking.
  • Added -Wno-lto-type-mismatch to avoid false-positive warnings from old GCC during LTO-enabled builds.
  • Added checking for TID (system thread id) to avoid hang on 32-bit Bionic/Android within pthread_mutex_lock().
  • Reworked MDBX_BUILD_TARGET of CMake builds.
  • Added CMAKE_HOST_ARCH and CMAKE_HOST_CAN_RUN_EXECUTABLES_BUILT_FOR_TARGET.

v0.11.6 at 2022-03-24

The stable release with the complete workaround for an incoherence flaw of Linux unified page/buffer cache. Nonetheless the cause for this trouble may be an issue of Intel CPU cache/MESI. See issue#269 for more information.

Acknowledgements:

Fixes:

  • Added complete workaround for an incoherence flaw of Linux unified page/buffer cache.
  • Fixed cursor reusing for read-only transactions.
  • Fixed copy&paste typo inside mdbx::cursor::find_multivalue().

Minors:

  • Minor refine C++ API for convenience.
  • Minor internals refines.
  • Added lib-static and lib-shared targets for make.
  • Added minor workaround for AppleClang 13.3 bug.
  • Clarified error messages of a signature/version mismatch.

v0.11.5 at 2022-02-23

The release with the temporary hotfix for a flaw of Linux unified page/buffer cache. See issue#269 for more information.

Acknowledgements:

Fixes:

  • Added hotfix for a flaw of Linux unified page/buffer cache.
  • Fixed/Reworked move-assignment operators for "managed" classes of C++ API.
  • Fixed potential SIGSEGV while open DB with overrided non-default page size.
  • Made mdbx_env_open() idempotence in failure cases.
  • Refined/Fixed pages reservation inside mdbx_update_gc() to avoid non-reclamation in a rare cases.
  • Fixed typo in a retained space calculation for the hsr-callback.

Minors:

  • Reworked functions for meta-pages, split-off non-volatile.
  • Disentangled C11-atomic fences/barriers and pure-functions (with __attribute__((__pure__))) to avoid compiler misoptimization.
  • Fixed hypotetic unaligned access to 64-bit dwords on ARM with __ARM_FEATURE_UNALIGNED defined.
  • Reasonable paranoia that makes clarity for code readers.
  • Minor fixes Doxygen references, comments, descriptions, etc.

v0.11.4 at 2022-02-02

The stable release with fixes for large and huge databases sized of 4..128 TiB.

Acknowledgements:

New features, extensions and improvements:

  • Added treating the UINT64_MAX value as maximum for given option inside mdbx_env_set_option().
  • Added to_hex/to_base58/to_base64::output(std::ostream&) overloads without using temporary string objects as buffers.
  • Added --geometry-jitter=YES|no option to the test framework.
  • Added support for Deno support by Kris Zyp.

Fixes:

  • Fixed handling MDBX_opt_rp_augment_limit for GC's records from huge transactions (Erigon/Akula/Ethereum).
  • Fixed build on Android (avoid including sys/sem.h).
  • Fixed missing copy assignment operator for mdbx::move_result.
  • Fixed missing & for std::ostream &operator<<() overloads.
  • Fixed unexpected EXDEV (Cross-device link) error from mdbx_env_copy().
  • Fixed base64 encoding/decoding bugs in auxillary C++ API.
  • Fixed overflow of pgno_t during checking PNL on 64-bit platforms.
  • Fixed excessive PNL checking after sort for spilling.
  • Reworked checking MAX_PAGENO and DB upper-size geometry limit.
  • Fixed build for some combinations of versions of MSVC and Windows SDK.

Minors:

  • Added workaround for CLANG bug D79919/PR42445.
  • Fixed build test on Android (using pthread_barrier_t stub).
  • Disabled C++20 concepts for CLANG < 14 on Android.
  • Fixed minor unused parameter warning.
  • Added CI for Android.
  • Refine/cleanup internal logging.
  • Refined line splitting inside hex/base58/base64 encoding to avoid \n at the end.
  • Added workaround for modern libstdc++ with CLANG < 4.x
  • Relaxed txn-check rules for auxiliary functions.
  • Clarified a comments and descriptions, etc.
  • Using the -fno-semantic interposition option to reduce the overhead to calling self own public functions.

v0.11.3 at 2021-12-31

Acknowledgements:

New features, extensions and improvements:

  • Added mdbx_cursor_get_batch().
  • Added MDBX_SET_UPPERBOUND.
  • C++ API is finalized now.
  • The GC update stage has been significantly speeded when fixing huge Erigon's transactions (Ethereum ecosystem).

Fixes:

  • Disabled C++20 concepts for stupid AppleClang 13.x
  • Fixed internal collision of MDBX_SHRINK_ALLOWED with MDBX_ACCEDE.

Minors:

  • Fixed returning MDBX_RESULT_TRUE (unexpected -1) from mdbx_env_set_option().
  • Added mdbx_env_get_syncbytes() and mdbx_env_get_syncperiod().
  • Clarified description of MDBX_INTEGERKEY.
  • Reworked/simplified mdbx_env_sync_internal().
  • Fixed extra assertion inside mdbx_cursor_put() for MDBX_DUPFIXED cases.
  • Avoiding extra looping inside mdbx_env_info_ex().
  • Explicitly enabled core dumps from stochastic tests scripts on Linux.
  • Fixed mdbx_override_meta() to avoid false-positive assertions.
  • For compatibility reverted returning MDBX_ENODATAfor some cases.

v0.11.2 at 2021-12-02

Acknowledgements:

Fixes:

Minors:

  • Fixed constexpr-related macros for legacy compilers.
  • Allowed to define 'CMAKE_CXX_STANDARD` using an environment variable.
  • Simplified collection statistics of page operation .
  • Added MDBX_FORCE_BUILD_AS_MAIN_PROJECT cmake option.
  • Remove unneeded #undef P_DIRTY.

v0.11.1 at 2021-10-23

Backward compatibility break:

The database format signature has been changed to prevent forward-interoperability with an previous releases, which may lead to a false positive diagnosis of database corruption due to flaws of an old library versions.

This change is mostly invisible:

  • previously versions are unable to read/write a new DBs;
  • but the new release is able to handle an old DBs and will silently upgrade ones.

Acknowledgements:

v0.10.5 at 2021-10-13 (obsolete, please use v0.11.1)

Unfortunately, the v0.10.5 accidentally comes not full-compatible with previous releases:

  • v0.10.5 can read/processing DBs created by previous releases, i.e. the backward-compatibility is provided;
  • however, previous releases may lead to false-corrupted state with DB that was touched by v0.10.5, i.e. the forward-compatibility is broken for v0.10.4 and earlier.

This cannot be fixed, as it requires fixing past versions, which as a result we will just get a current version. Therefore, it is recommended to use v0.11.1 instead of v0.10.5.

Acknowledgements:

Fixes:

  • Fixed unaligned access regression after the #pragma pack fix for modern compilers.
  • Added UBSAN-test to CI to avoid a regression(s) similar to lately fixed.
  • Fixed possibility of meta-pages clashing after manually turn to a particular meta-page using mdbx_chk utility.

Minors:

  • Refined handling of weak or invalid meta-pages while a DB opening.
  • Refined providing information for the @MAIN and @GC sub-databases of a last committed modification transaction's ID.

v0.10.4 at 2021-10-10

Acknowledgements:

Fixes:

  • Fixed possibility of looping update GC during transaction commit (no public issue since the problem was discovered inside Positive Technologies).
  • Fixed #pragma pack to avoid provoking some compilers to generate code with unaligned access.
  • Fixed noexcept for potentially throwing txn::put() of C++ API.

Minors:

  • Added stochastic test script for checking small transactions cases.
  • Removed extra transaction commit/restart inside test framework.
  • In debugging builds fixed a too small (single page) by default DB shrink threshold.

v0.10.3 at 2021-08-27

Acknowledgements:

Extensions and improvements:

  • Added cursor::erase() overloads for key and for key-value.
  • Resolve minor Coverity Scan issues (no fixes but some hint/comment were added).
  • Resolve minor UndefinedBehaviorSanitizer issues (no fixes but some workaround were added).

Fixes:

Minors:

  • Fixed getting revision number from middle of history during amalgamation (GNU Makefile).
  • Fixed search GCC tools for LTO (CMake scripts).
  • Fixed/reorder dirs list for search CLANG tools for LTO (CMake scripts).
  • Fixed/workarounds for CLANG < 9.x
  • Fixed CMake warning about compatibility with 3.8.2

v0.10.2 at 2021-07-26

Acknowledgements:

New features, extensions and improvements:

  • Allow to predefine/override MDBX_BUILD_TIMESTAMP for builds reproducibility.
  • Added options support for long-stochastic script.
  • Avoided MDBX_TXN_FULL error for large transactions when possible.
  • The MDBX_READERS_LIMIT increased to 32767.
  • Raise MDBX_TOO_LARGE under Valgrind/ASAN if being opened DB is 100 larger than RAM (to avoid hangs and OOM).
  • Minimized the size of poisoned/unpoisoned regions to avoid Valgrind/ASAN stuck.
  • Added more workarounds for QEMU for testing builds for 32-bit platforms, Alpha and Sparc architectures.
  • mdbx_chk now skips iteration & checking of DB' records if corresponding page-tree is corrupted (to avoid SIGSEGV, ASAN failures, etc).
  • Added more checks for rare/fuzzing corruption cases.

Backward compatibility break:

  • Use file VERSION.txt for version information instead of VERSION to avoid collision with #include <version>.
  • Rename slice::from/to_FOO_bytes() to `slice::envisage_from/to_FOO_length()'.
  • Rename MDBX_TEST_EXTRA make's variable to MDBX_SMOKE_EXTRA.
  • Some details of the C++ API have been changed for subsequent freezing.

Fixes:

v0.10.1 at 2021-06-01

Acknowledgements:

New features:

  • Added -p option to mdbx_stat utility for printing page operations statistic.
  • Added explicit checking for and warning about using unfit github's archives.
  • Added fallback from OFD locking to legacy non-OFD POSIX file locks on an EINVAL error.
  • Added Plan 9 network file system to the whitelist for an ability to open a DB in exclusive mode.
  • Support for opening from WSL2 environment a DB hosted on Windows drive and mounted via DrvFs (i.e by Plan 9 noted above).

Fixes:

v0.10.0 at 2021-05-09

Acknowledgements:

New features:

  • Added mdbx_env_set_option() and mdbx_env_get_option() for controls various runtime options for an environment (announce of this feature was missed in a previous news).
  • Added MDBX_DISABLE_PAGECHECKS build option to disable some checks to reduce an overhead and detection probability of database corruption to a values closer to the LMDB. The MDBX_DISABLE_PAGECHECKS=1 provides a performance boost of about 10% in CRUD scenarios, and conjointly with the MDBX_ENV_CHECKPID=0 and MDBX_TXN_CHECKOWNER=0 options can yield up to 30% more performance compared to LMDB.
  • Using float point (exponential quantized) representation for internal 16-bit values of grow step and shrink threshold when huge ones (https://web.archive.org/web/20220414235959/https://github.com/erthink/libmdbx/issues/166). To minimize the impact on compatibility, only the odd values inside the upper half of the range (i.e. 32769..65533) are used for the new representation.
  • Added the mdbx_drop similar to LMDB command-line tool to purge or delete (sub)database(s).
  • Ruby bindings is available now by Mahlon E. Smith.
  • Added MDBX_ENABLE_MADVISE build option which controls the use of POSIX madvise() hints and friends.
  • The internal node sizes were refined, resulting in a reduction in large/overflow pages in some use cases and a slight increase in limits for a keys size to ≈½ of page size.
  • Added to mdbx_chk output number of keys/items on pages.
  • Added explicit install-strip and install-no-strip targets to the Makefile (https://web.archive.org/web/20220414235959/https://github.com/erthink/libmdbx/pull/180).
  • Major rework page splitting (af9b7b5605) for
    • An "auto-appending" feature upon insertion for both ascending and descending key sequences. As a result, the optimality of page filling increases significantly (more densely, less slackness) while inserting ordered sequences of keys,
    • A "splitting at middle" to make page tree more balanced on average.
  • Added mdbx_get_sysraminfo() to the API.
  • Added guessing a reasonable maximum DB size for the default upper limit of geometry (https://web.archive.org/web/20220414235959/https://github.com/erthink/libmdbx/issues/183).
  • Major rework internal labeling of a dirty pages (958fd5b947) for a "transparent spilling" feature with the gist to make a dirty pages be ready to spilling (writing to a disk) without further altering ones. Thus in the MDBX_WRITEMAP mode the OS kernel able to oust dirty pages to DB file without further penalty during transaction commit. As a result, page swapping and I/O could be significantly reduced during extra large transactions and/or lack of memory.
  • Minimized reading leaf-pages during dropping subDB(s) and nested trees.
  • Major rework a spilling of dirty pages to support LRU policy and prioritization for a large/overflow pages.
  • Statistics of page operations (split, merge, copy, spill, etc) now available through mdbx_env_info_ex().
  • Auto-setup limit for length of dirty pages list (MDBX_opt_txn_dp_limit option).
  • Support make options to list available build options.
  • Support make help to list available make targets.
  • Silently make's build by default.
  • Preliminary Python bindings is available now by Noel Kuntze (https://web.archive.org/web/20220414235959/https://github.com/erthink/libmdbx/issues/147).

Backward compatibility break:

  • The MDBX_AVOID_CRT build option was renamed to MDBX_WITHOUT_MSVC_CRT. This option is only relevant when building for Windows.
  • The mdbx_env_stat() always, and mdbx_env_stat_ex() when called with the zeroed transaction parameter, now internally start temporary read transaction and thus may returns MDBX_BAD_RSLOT error. So, just never use deprecated mdbx_env_stat()' and call mdbx_env_stat_ex()` with transaction parameter.
  • The build option MDBX_CONFIG_MANUAL_TLS_CALLBACK was removed and now just a non-zero value of the MDBX_MANUAL_MODULE_HANDLER macro indicates the requirement to manually call mdbx_module_handler() when loading libraries and applications uses statically linked libmdbx on an obsolete Windows versions.

Fixes:

v0.9.3 at 2021-02-02

Acknowledgements:

Removed options and features:

  • Drop MDBX_HUGE_TRANSACTIONS build-option (now no longer required).

New features:

  • Package for FreeBSD is available now by Mahlon E. Smith.
  • New API functions to get/set various options (https://web.archive.org/web/20220414235959/https://github.com/erthink/libmdbx/issues/128):
    • the maximum number of named databases for the environment;
    • the maximum number of threads/reader slots;
    • threshold (since the last unsteady commit) to force flush the data buffers to disk;
    • relative period (since the last unsteady commit) to force flush the data buffers to disk;
    • limit to grow a list of reclaimed/recycled page's numbers for finding a sequence of contiguous pages for large data items;
    • limit to grow a cache of dirty pages for reuse in the current transaction;
    • limit of a pre-allocated memory items for dirty pages;
    • limit of dirty pages for a write transaction;
    • initial allocation size for dirty pages list of a write transaction;
    • maximal part of the dirty pages may be spilled when necessary;
    • minimal part of the dirty pages should be spilled when necessary;
    • how much of the parent transaction dirty pages will be spilled while start each child transaction;
  • Unlimited/Dynamic size of retired and dirty page lists (https://web.archive.org/web/20220414235959/https://github.com/erthink/libmdbx/issues/123).
  • Added -p option (purge subDB before loading) to mdbx_load tool.
  • Reworked spilling of large transaction and committing of nested transactions:
    • page spilling code reworked to avoid the flaws and bugs inherited from LMDB;
    • limit for number of dirty pages now is controllable at runtime;
    • a spilled pages, including overflow/large pages, now can be reused and refunded/compactified in nested transactions;
    • more effective refunding/compactification especially for the loosed page cache.
  • Added MDBX_ENABLE_REFUND and MDBX_PNL_ASCENDING internal/advanced build options.
  • Added mdbx_default_pagesize() function.
  • Better support architectures with a weak/relaxed memory consistency model (ARM, AARCH64, PPC, MIPS, RISC-V, etc) by means C11 atomics.
  • Speed up page number lists and dirty page lists (https://web.archive.org/web/20220414235959/https://github.com/erthink/libmdbx/issues/132).
  • Added LIBMDBX_NO_EXPORTS_LEGACY_API build option.

Fixes:

v0.9.2 at 2020-11-27

Acknowledgements:

Added features:

  • Provided package for buildroot.
  • Binding for Nim is available now by Jens Alfke.
  • Added mdbx_env_delete() for deletion an environment files in a proper and multiprocess-safe way.
  • Added mdbx_txn_commit_ex() with collecting latency information.
  • Fast completion pure nested transactions.
  • Added LIBMDBX_INLINE_API macro and inline versions of some API functions.
  • Added mdbx_cursor_copy() function.
  • Extended tests for checking cursor tracking.
  • Added MDBX_SET_LOWERBOUND operation for mdbx_cursor_get().

Fixes:

v0.9.1 2020-09-30

Added features:

  • Preliminary C++ API with support for C++17 polymorphic allocators.
  • Online C++ API reference by Doxygen.
  • Quick reference for Insert/Update/Delete operations.
  • Explicit MDBX_SYNC_DURABLE to sync modes for API clarity.
  • Explicit MDBX_ALLDUPS and MDBX_UPSERT for API clarity.
  • Support for read transactions preparation (MDBX_TXN_RDONLY_PREPARE flag).
  • Support for cursor preparation/(pre)allocation and reusing (mdbx_cursor_create() and mdbx_cursor_bind() functions).
  • Support for checking database using specified meta-page (see mdbx_chk -h).
  • Support for turn to the specific meta-page after checking (see mdbx_chk -h).
  • Support for explicit reader threads (de)registration.
  • The mdbx_txn_break() function to explicitly mark a transaction as broken.
  • Improved handling of corrupted databases by mdbx_chk utility and mdbx_walk_tree() function.
  • Improved DB corruption detection by checking parent-page-txnid.
  • Improved opening large DB (> 4Gb) from 32-bit code.
  • Provided pure-function and const-function attributes to C API.
  • Support for user-settable context for transactions & cursors.
  • Revised API and documentation related to Handle-Slow-Readers callback feature.

Deprecated functions and flags:

  • For clarity and API simplification the MDBX_MAPASYNC flag is deprecated. Just use MDBX_SAFE_NOSYNC or MDBX_UTTERLY_NOSYNC instead of it.
  • MDBX_oom_func, mdbx_env_set_oomfunc() and mdbx_env_get_oomfunc() replaced with MDBX_hsr_func, mdbx_env_get_hsr and mdbx_env_get_hsr().

Fixes:

  • Fix mdbx_strerror() for MDBX_BUSY error (no error description is returned).
  • Fix update internal meta-geo information in read-only mode (EACCESS or EBADFD error).
  • Fix mdbx_page_get() null-defer when DB corrupted (crash by SIGSEGV).
  • Fix mdbx_env_open() for re-opening after non-fatal errors (mdbx_chk unexpected failures).
  • Workaround for MSVC 19.27 static_assert() bug.
  • Doxygen descriptions and refinement.
  • Update Valgrind's suppressions.
  • Workaround to avoid infinite loop of 'nested' testcase on MIPS under QEMU.
  • Fix a lot of typos & spelling (Thanks to Josh Soref for PR).
  • Fix getopt() messages for Windows (Thanks to Andrey Sporaw for reporting).
  • Fix MSVC compiler version requirements (Thanks to Andrey Sporaw for reporting).
  • Workarounds for QEMU's bugs to run tests for cross-builded library under QEMU.
  • Now C++ compiler optional for building by CMake.

v0.9.0 2020-07-31 (not a release, but API changes)

Added features:

  • Online C API reference by Doxygen.
  • Separated enums for environment, sub-databases, transactions, copying and data-update flags.

Deprecated functions and flags:

  • Usage of custom comparators and the mdbx_dbi_open_ex() are deprecated, since such databases couldn't be checked by the mdbx_chk utility. Please use the value-to-key functions to provide keys that are compatible with the built-in libmdbx comparators.

2020-07-06

  • Added support multi-opening the same DB in a process with SysV locking (BSD).
  • Fixed warnings & minors for LCC compiler (E2K).
  • Enabled to simultaneously open the same database from processes with and without the MDBX_WRITEMAP option.
  • Added key-to-value, mdbx_get_keycmp() and mdbx_get_datacmp() functions (helpful to avoid using custom comparators).
  • Added ENABLE_UBSAN CMake option to enabling the UndefinedBehaviorSanitizer from GCC/CLANG.
  • Workaround for CLANG bug.
  • Returning MDBX_CORRUPTED in case all meta-pages are weak and no other error.
  • Refined mode bits while auto-creating LCK-file.
  • Avoids unnecessary database file re-mapping in case geometry changed by another process(es). From the user's point of view, the MDBX_UNABLE_EXTEND_MAPSIZE error will now be returned less frequently and only when using the DB in the current process really requires it to be reopened.
  • Remapping on-the-fly and of the database file was implemented. Now remapping with a change of address is performed automatically if there are no dependent readers in the current process.

2020-06-12

  • Minor change versioning. The last number in the version now means the number of commits since last release/tag.
  • Provide ChangeLog file.
  • Fix for using libmdbx as a C-only sub-project with CMake.
  • Fix mdbx_env_set_geometry() for case it is called from an opened environment outside of a write transaction.
  • Add support for huge transactions and MDBX_HUGE_TRANSACTIONS build-option (default OFF).
  • Refine LTO (link time optimization) for clang.
  • Force enabling exceptions handling for MSVC (/EHsc option).

2020-06-05

  • Support for Android/Bionic.
  • Support for iOS.
  • Auto-handling MDBX_NOSUBDIR while opening for any existing database.
  • Engage github-actions to make release-assets.
  • Clarify API description.
  • Extended keygen-cases in stochastic test.
  • Fix fetching of first/lower key from LEAF2-page during page merge.
  • Fix missing comma in array of error messages.
  • Fix div-by-zero while copy-with-compaction for non-resizable environments.
  • Fixes & enhancements for custom-comparators.
  • Fix MDBX_WITHOUT_MSVC_CRT option and missing ntdll.def.
  • Fix mdbx_env_close() to work correctly called concurrently from several threads.
  • Fix null-deref in an ASAN-enabled builds while opening the environment with error and/or read-only.
  • Fix AddressSanitizer errors after closing the environment.
  • Fix/workaround to avoid GCC 10.x pedantic warnings.
  • Fix using ENODATA for FreeBSD.
  • Avoid invalidation of DBI-handle(s) when it just closes.
  • Avoid using pwritev() for single-writes (up to 10% speedup for some kernels & scenarios).
  • Avoiding MDBX_UTTERLY_NOSYNC as result of flags merge.
  • Add mdbx_dbi_dupsort_depthmask() function.
  • Add MDBX_CP_FORCE_RESIZEABLE option.
  • Add deprecated MDBX_MAP_RESIZED for compatibility.
  • Add MDBX_BUILD_TOOLS option (default ON).
  • Refine mdbx_dbi_open_ex() to safe concurrently opening the same handle from different threads.
  • Truncate clk-file during environment closing. So a zero-length lck-file indicates that the environment was closed properly.
  • Refine mdbx_update_gc() for huge transactions with small sizes of database page.
  • Extends dump/load to support all MDBX attributes.
  • Avoid upsertion the same key-value data, fix related assertions.
  • Rework min/max length checking for keys & values.
  • Checking the order of keys on all pages during checking.
  • Support CFLAGS_EXTRA make-option for convenience.
  • Preserve the last txnid while copying with compactification.
  • Auto-reset running transaction in mdbx_txn_renew().
  • Automatically abort errored transaction in mdbx_txn_commit().
  • Auto-choose page size for large databases.
  • Rearrange source files, rework build, options-support by CMake.
  • Crutch for WSL1 (Windows subsystem for Linux).
  • Refine install/uninstall targets.
  • Support for Valgrind 3.14 and later.
  • Add check-analyzer check-ubsan check-asan check-leak targets to Makefile.
  • Minor fix/workaround to avoid UBSAN traps for memcpy(ptr, NULL, 0).
  • Avoid some GCC-analyzer false-positive warnings.

2020-03-18

  • Workarounds for Wine (Windows compatibility layer for Linux).
  • MDBX_MAP_RESIZED renamed to MDBX_UNABLE_EXTEND_MAPSIZE.
  • Clarify API description, fix typos.
  • Speedup runtime checks in debug/checked builds.
  • Added checking for read/write transactions overlapping for the same thread, added MDBX_TXN_OVERLAPPING error and MDBX_DBG_LEGACY_OVERLAP option.
  • Added mdbx_key_from_jsonInteger(), mdbx_key_from_double(), mdbx_key_from_float(), mdbx_key_from_int64() and mdbx_key_from_int32() functions. See mdbx.h for description.
  • Fix compatibility (use zero for invalid DBI).
  • Refine/clarify error messages.
  • Avoids extra error messages "bad txn" from mdbx_chk when DB is corrupted.

2020-01-21

  • Fix mdbx_load utility for custom comparators.
  • Fix checks related to MDBX_APPEND flag inside mdbx_cursor_put().
  • Refine/fix dbi_bind() internals.
  • Refine/fix handling STATUS_CONFLICTING_ADDRESSES.
  • Rework MDBX_DBG_DUMP option to avoid disk I/O performance degradation.
  • Add built-in help to test tool.
  • Fix mdbx_env_set_geometry() for large page size.
  • Fix env_set_geometry() for large pagesize.
  • Clarify API description & comments, fix typos.

2019-12-31

  • Fix returning MDBX_RESULT_TRUE from page_alloc().
  • Fix false-positive ASAN issue.
  • Fix assertion for MDBX_NOTLS option.
  • Rework MADV_DONTNEED threshold.
  • Fix mdbx_chk utility for don't checking some numbers if walking on the B-tree was disabled.
  • Use page's mp_txnid for basic integrity checking.
  • Add MDBX_FORCE_ASSERTIONS built-time option.
  • Rework MDBX_DBG_DUMP to avoid performance degradation.
  • Rename MDBX_NOSYNC to MDBX_SAFE_NOSYNC for clarity.
  • Interpret ERROR_ACCESS_DENIED from OpenProcess() as 'process exists'.
  • Avoid using FILE_FLAG_NO_BUFFERING for compatibility with small database pages.
  • Added install section for CMake.

2019-12-02

  • Support for Mac OSX, FreeBSD, NetBSD, OpenBSD, DragonFly BSD, OpenSolaris, OpenIndiana (AIX and HP-UX pending).
  • Use bootid for decisions of rollback.
  • Counting retired pages and extended transaction info.
  • Add MDBX_ACCEDE flag for database opening.
  • Using OFD-locks and tracking for in-process multi-opening.
  • Hot backup into pipe.
  • Support for cmake & amalgamated sources.
  • Fastest internal sort implementation.
  • New internal dirty-list implementation with lazy sorting.
  • Support for lazy-sync-to-disk with polling.
  • Extended key length.
  • Last update transaction number for each sub-database.
  • Automatic read ahead enabling/disabling.
  • More auto-compactification.
  • Using -fsanitize=undefined and -Wpedantic options.
  • Rework page merging.
  • Nested transactions.
  • API description.
  • Checking for non-local filesystems to avoid DB corruption.

For early changes see the git commit history.