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mdbx: drop/deprecate MDBX_MAPASYNC.

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Change-Id: I472f97f568a32325eb056c8ee4d2f2350a473bda
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Leonid Yuriev
2020-08-01 19:13:17 +03:00
parent 135bead730
commit 5e43ee61a2
11 changed files with 182 additions and 214 deletions
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17
README.md
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@@ -227,7 +227,7 @@ the user's point of view.
7. Fast estimation of range query result volume, i.e. how many items can
be found between a `KEY1` and a `KEY2`. This is a prerequisite for build
and/or optimize query execution plans.
> _libmdbx_ performs a rough estimate based on common B-tree pages of the paths from root to corresponding keys.
> _libmdbx_ performs a rough estimate based on common B-tree pages of the paths from root to corresponding keys.
8. `mdbx_chk` tool for database integrity check.
@@ -259,9 +259,13 @@ pair, to the first, to the last, or not set to anything.
## Other fixes and specifics
1. Fixed more than 10 significant errors, in particular: page leaks, wrong sub-database statistics, segfault in several conditions, nonoptimal page merge strategy, updating an existing record with a change in data size (including for multimap), etc.
1. Fixed more than 10 significant errors, in particular: page leaks,
wrong sub-database statistics, segfault in several conditions,
nonoptimal page merge strategy, updating an existing record with
a change in data size (including for multimap), etc.
2. All cursors can be reused and should be closed explicitly, regardless ones were opened within a write or read transaction.
2. All cursors can be reused and should be closed explicitly,
regardless ones were opened within a write or read transaction.
3. Opening database handles are spared from race conditions and
pre-opening is not needed.
@@ -269,10 +273,9 @@ pre-opening is not needed.
4. Returning `MDBX_EMULTIVAL` error in case of ambiguous update or delete.
5. Guarantee of database integrity even in asynchronous unordered write-to-disk mode.
> _libmdbx_ propose additional trade-off by implementing append-like manner for updates
> in `MDBX_SAFE_NOSYNC` and `MDBX_WRITEMAP|MDBX_MAPASYNC` modes, that avoid database corruption after a system crash
> contrary to LMDB. Nevertheless, the `MDBX_UTTERLY_NOSYNC` mode is available to match LMDB behaviour,
> and for special use-cases.
> _libmdbx_ propose additional trade-off by `MDBX_SAFE_NOSYNC` with append-like manner for updates,
> that avoids database corruption after a system crash contrary to LMDB.
> Nevertheless, the `MDBX_UTTERLY_NOSYNC` mode is available to match behaviour of the `MDB_NOSYNC` in LMDB.
6. On **MacOS & iOS** the `fcntl(F_FULLFSYNC)` syscall is used _by
default_ to synchronize data with the disk, as this is [the only way to