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Acknowledgements: ----------------- - [Mahlon E. Smith](https://github.com/mahlonsmith) for [Ruby bindings](https://rubygems.org/gems/mdbx/). - [Alex Sharov](https://github.com/AskAlexSharov) for [mdbx-go](https://github.com/torquem-ch/mdbx-go), bug reporting and testing. - [Artem Vorotnikov](https://github.com/vorot93) for bug reporting and PR. - [Paolo Rebuffo](https://www.linkedin.com/in/paolo-rebuffo-8255766/), [Alexey Akhunov](https://github.com/AlexeyAkhunov) and Mark Grosberg for donations. - [Noel Kuntze](https://github.com/Thermi) for preliminary [Python bindings](https://github.com/Thermi/libmdbx/tree/python-bindings) 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://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](https://rubygems.org/gems/mdbx/) is available now by [Mahlon E. Smith](https://github.com/mahlonsmith). - 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://github.com/erthink/libmdbx/pull/180). - Major rework page splitting (af9b7b560505684249b76730997f9e00614b8113) 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://github.com/erthink/libmdbx/issues/183). - Major rework internal labeling of a dirty pages (958fd5b9479f52f2124ab7e83c6b18b04b0e7dda) 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](https://en.wikipedia.org/wiki/Cache_replacement_policies#Least_recently_used_(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](https://github.com/Thermi/libmdbx/tree/python-bindings) is available now by [Noel Kuntze](https://github.com/Thermi) (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: ------ - Fixed performance regression due non-optimal C11 atomics usage (https://github.com/erthink/libmdbx/issues/160). - Fixed "reincarnation" of subDB after it deletion (https://github.com/erthink/libmdbx/issues/168). - Fixed (disallowing) implicit subDB deletion via operations on `@MAIN`'s DBI-handle. - Fixed a crash of `mdbx_env_info_ex()` in case of a call for a non-open environment (https://github.com/erthink/libmdbx/issues/171). - Fixed the selecting/adjustment values inside `mdbx_env_set_geometry()` for implicit out-of-range cases (https://github.com/erthink/libmdbx/issues/170). - Fixed `mdbx_env_set_option()` for set initial and limit size of dirty page list ((https://github.com/erthink/libmdbx/issues/179). - Fixed an unreasonably huge default upper limit for DB geometry (https://github.com/erthink/libmdbx/issues/183). - Fixed `constexpr` specifier for the `slice::invalid()`. - Fixed (no)readahead auto-handling (https://github.com/erthink/libmdbx/issues/164). - Fixed non-alloy build for Windows. - Switched to using Heap-functions instead of LocalAlloc/LocalFree on Windows. - Fixed `mdbx_env_stat_ex()` to returning statistics of the whole environment instead of MainDB only (https://github.com/erthink/libmdbx/issues/190). - Fixed building by GCC 4.8.5 (added workaround for a preprocessor's bug). - Fixed building C++ part for iOS <= 13.0 (unavailability of `std::filesystem::path`). - Fixed building for Windows target versions prior to Windows Vista (`WIN32_WINNT < 0x0600`). - Fixed building by MinGW for Windows (https://github.com/erthink/libmdbx/issues/155). TODO for a next releases: ------------------------- - [Get rid of dirty-pages list in MDBX_WRITEMAP mode](https://github.com/erthink/libmdbx/issues/193). - [Large/Overflow pages accounting for dirty-room](https://github.com/erthink/libmdbx/issues/192). - [C++ Buffer issue](https://github.com/erthink/libmdbx/issues/191). - Finalize C++ API (few typos and trivia bugs are still likely for now). - [Support for RAW devices](https://github.com/erthink/libmdbx/issues/124). - [Test framework issue](https://github.com/erthink/libmdbx/issues/127). - [Support MessagePack for Keys & Values](https://github.com/erthink/libmdbx/issues/115). - [Engage new terminology](https://github.com/erthink/libmdbx/issues/137). - Packages for [Astra Linux](https://astralinux.ru/), [ALT Linux](https://www.altlinux.org/), [ROSA Linux](https://www.rosalinux.ru/), Fedora/RHEL, Debian/Ubuntu.
49 lines
1.2 KiB
Groff
49 lines
1.2 KiB
Groff
.\" Copyright 2021 Leonid Yuriev <leo@yuriev.ru>.
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.\" Copyright 2014-2021 Howard Chu, Symas Corp. All Rights Reserved.
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.\" Copying restrictions apply. See COPYRIGHT/LICENSE.
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.TH MDBX_DROP 1 "2021-05-09" "MDBX 0.10.0"
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.SH NAME
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mdbx_drop \- MDBX database delete tool
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.SH SYNOPSIS
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.B mdbx_drop
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[\c
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.BR \-V ]
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[\c
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.BR \-d ]
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[\c
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.BI \-s \ subdb\fR]
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[\c
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.BR \-n ]
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.BR \ dbpath
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.SH DESCRIPTION
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The
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.B mdbx_drop
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utility empties or deletes a database in the specified
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environment.
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.SH OPTIONS
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.TP
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.BR \-V
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Write the library version number to the standard output, and exit.
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.TP
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.BR \-d
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Delete the specified database, don't just empty it.
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.TP
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.BR \-s \ subdb
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Operate on a specific subdatabase. If no database is specified, only the main database is dropped.
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.TP
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.BR \-n
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Dump an MDBX database which does not use subdirectories.
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This is legacy option. For now MDBX handles this automatically.
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.SH DIAGNOSTICS
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Exit status is zero if no errors occur.
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Errors result in a non-zero exit status and
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a diagnostic message being written to standard error.
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.SH "SEE ALSO"
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.BR mdbx_load (1),
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.BR mdbx_copy (1),
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.BR mdbx_chk (1),
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.BR mdbx_stat (1)
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.SH AUTHOR
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Howard Chu of Symas Corporation <http://www.symas.com>
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