# redb - Changelog

## Unreleased
* Optimize `Table::pop_first()` and `Table::pop_last()` to be about 2x faster.

## 4.1.0 - 2026-04-19
**This release contains a large number of bug fixes discovered by AI coding agents**

* Fix a bug where `MultimapValue::len()` and `is_empty()` returned stale counts after
  consuming entries via `next_back()`.
* Fix a bug where `restore_savepoint()` used in a non-`Immediate` durability transaction and when
  there are persistent savepoints newer than the one being restored, could fail
  with `SavepointError::InvalidSavepoint`, but the savepoint would actually be partially applied.
  The call now fails up front with `SavepointError::ImmediateDurabilityRequired`.
* Fix a bug in `restore_savepoint()` where modifications made earlier in the transaction might
  not be reverted.
* Fix a bug where renaming a table that was already modified in the same transaction could cause
  the database to become corrupted.
* Fix a bug where calling `restore_savepoint()` after modifying a table in the same
  transaction could cause the table to become corrupted in a future transaction.
* Fix a panic when `delete_table()` was called on a table that had been modified in the same
  transaction.
* Fix a panic in `restore_savepoint()` when passed a `Savepoint` from a different `Database`.
  `SavepointError::InvalidSavepoint` is now returned instead.
* Fix a bug where a transaction that created a persistent savepoint and was then
  aborted could cause the database file to grow excessively, until the `Database` was dropped.
* Fix a panic in `check_integrity()` when called while another transaction is still alive.
  `DatabaseError::TransactionInProgress` is now returned instead.
* Fix a bug where aborting a transaction that called `restore_savepoint()` with a savepoint
  when a newer savepoint existed could cause database space to be leaked.
* Fix a bug where aborting a transaction that called `restore_savepoint()` would leave more
  recent savepoints invalid.
* Improve performance when reading concurrently from multiple threads. Around 15% speedup on some benchmarks.
* Optimize cache usage, and general write performance. Around 1.5x speedup on some benchmarks.
* Optimize memory usage.
* Other performance optimizations.

## 4.0.0 - 2026-04-02
* Implement `Drop` on `AccessGuardMut` and `AccessGuardMutInPlace`, which requires that these be dropped
  before the `Table` they borrow from.
  This fixes a critical bug where the accessor could outlive the `Table`, and be dropped after the
  transaction had already committed. This could cause data loss due to the data in the accessor
  being written out after the transaction had already completed.
* Remove `Legacy` type. To migrate off the `Legacy` type, use the `Legacy` type in the 3.x release
  and copy the data to a table with plain tuples, before upgrading to the 4.x release.

## 3.1.3 - 2026-04-02
* Fix a data loss bug which can occur when the guard returned from `Table::get_mut()` is dropped
  after the transaction has been committed.
* Add a warning to `Table::insert_reserve()` indicating that it can cause data loss and recommending
  to upgrade to the 4.0.0 release.

## 3.1.2 - 2026-04-01
* Reduce memory usage of open databases

## 3.1.1 - 2026-03-08
* Fix panic which could occur when inserting into a table with fixed size keys when `debug_assertions` are enabled
* Add additional information to the stats returned by `cache_stats()`

## 3.1.0 - 2025-09-25
* Implement `std::error::Error` for `SetDurabilityError`
* Fix compilation error on various non-tier-1 platforms, such as wasm32-unknown

## 3.0.2 - 2025-09-16
* Fix performance issue where a transaction with a large number of writes would cause
  `WriteTransaction::abort()` and committing non-durable transactions to become slow.

## 3.0.1 - 2025-08-23
* Fix correctness issue with `range()`, `extract_from_if()`, and `retain_in()`. If a RangeBounds
  with `start` > `end` was passed as an argument and `start` and `end` keys were stored in different
  internal pages in the database (i.e. a sufficient condition is that more than 4KiB of key-value
  pairs were between the two keys) then these methods would perform as if the argument had been
  `start..`
* Fix performance regression, from redb 2.x, where `Durability::None` commits could become linearly
  slower during a series of transactions.

## 2.6.3 - 2025-08-23
* Fix correctness issue with `range()`, `extract_from_if()`, and `retain_in()`. If a RangeBounds
  with `start` > `end` was passed as an argument and `start` and `end` keys were stored in different
  internal pages in the database (i.e. a sufficient condition is that more than 4KiB of key-value
  pairs were between the two keys) then these methods would perform as if the argument had been
  `start..`

## 1.5.2 - 2025-08-23
* Fix correctness issue with `range()`, `drain()`, and `drain_filter()`. If a RangeBounds
  with `start` > `end` was passed as an argument and `start` and `end` keys were stored in different
  internal pages in the database (i.e. a sufficient condition is that more than 4KiB of key-value
  pairs were between the two keys) then these methods would perform as if the argument had been
  `start..`

## 3.0.0 - 2025-08-09

### Removes support for file format v2.
Use `Database::upgrade()`, in redb 2.6, to migrate to the v3 file format.

### General storage optimizations
The v3 file format has been further optimized to reduce the size of the database. Databases with only
a few small keys will see the largest benefit, and the minimum size of a database file has decreased
from ~2.5MiB to ~50KiB. To achieve the smallest file size call `Database::compact()` before
dropping the `Database`.

Additionally, performance is ~15% better in bulk load benchmarks. This was achieved by implementing
a custom hash function for various in-memory `HashSet`s and `HashMap`s, and by optimizing the usage
of buffers held in `Arc`s to reduce the number of atomic instructions executed.

### Optimize storage of tuple types
Storage of variable width tuple types with arity greater than 1 is more efficient. The new format
elides the length of any fixed width fields and uses varint encoding for the lengths of all variable
width fields.

Note that this encoding is not compatible with the serialization of variable width tuples used in prior versions.
To load tuple data created prior to version 3.0, wrap them in the `Legacy` type.
For example, `TableDefinition<u64, (&str, u32)>` becomes `TableDefinition<u64, Legacy<(&str, u32)>>`.
Fixed width tuples, such as `(u32, u64)` are backwards compatible.

### Derive for Key and Value traits
`Key` and `Value` can be derived using the `redb-derive` crate. Note that it does not support
schema migration. The recommended pattern to migrate schema is to create a new table, and then
perform a migration from the old table to the new table.

### Read-only multi-process support
Multiple processes may open the same database file for reading by using the new `ReadOnlyDatabase`
type. On platforms which support file locks, this acquires a shared lock on the database file.

### Enable garbage collection in Durability::None transactions
Non-durable transactions will now free pages when possible (pages allocated in a preceding
non-durable transaction which are no longer referenced).
This resolves an issue where a long sequence of non-durable transactions led to significant growth
in the size of the database file.
This change increases the RAM required for a sequence of non-durable transactions, such that RAM
proportional to the net change in the database is now used. However, it will never use more than
about 0.2% of the database file size.

### Other changes

* Add `ReadOnlyDatabase`
* Add `Builder::open_read_only()`
* Add `StorageBackend::close()`
* Add `Table::get_mut()`
* Add `chrono_v0_4` feature flag which enables serialization of the `NaiveDate`, `NaiveTime`,
  `NaiveDatetime`, `DateTime<FixedOffset>`, and `FixedOffset` types in the `chrono` crate
* Add `uuid` feature flag which enables serialization of the `Uuid` type in the `uuid` crate
* Change `StorageBackend::read()` to accept a `&mut [u8]` output argument instead of returning
  a `Vec<u8>`
* Change `Table::insert_reserve()` to take `usize` instead of `u32` as the argument type
* Change `TypeName::name()` to be public
* Change `ReadTransactionStillInUse` to contain a `Box`
* Change `set_durability()` to return a `Result`
* Move `Database::cache_stats()` and `Database::begin_read()` to `ReadableDatabase` trait
* Rename `AccessGuardMut` to `AccessGuardMutInPlace`. Note that a new `AccessGuardMut` struct has
  been added; it serves a different purpose
* Remove `Durability::Paranoid`
* Fix a rare case where `check_integrity()` returned `Ok(false)` even though no repair was required,
  when called on a database that was not shutdown cleanly and was automatically repaired when opened
* Disallow access to the database from read transactions after the `Database` as been
  dropped. Access will now return `DatabaseClosed`

## 2.6.2 - 2025-08-02
* Forward compatibility improvement which makes the file format more flexible to support a potential
  future optimization

## 2.6.1 - 2025-07-24
* Fix a forward compatibility issue which caused a crash when opening databases created with redb
  3.x. Note that opening 3.x databases with redb 2.x is not generally supported and only works
  in certain situations.

## 2.6.0 - 2025-05-22

### Add support for the v3 file format.
This file format improves savepoints.
Savepoints in the v3 format have constant, and small, overhead. Creating
and restoring them is also much faster. The v3 file format also supports
savepoints on large databases (v2 has a limit around 32TB). This release
creates v2 databases by default. Use `Builder::create_with_file_format_v3()`
and `Database::upgrade()`, respectively, to enable and migrate to v3.

**The upcoming 3.0 release will only support the v3 file format.**

* Add `Builder::create_with_file_format_v3()`
* Add `Database::upgrade()`

## 2.5.0 - 2025-04-21
* Add `rename_table()` and `rename_multimap_table()`
* Add `Key` and `Value` implementations for the unary tuple type (i.e. `(T,)`)
* Fix an issue which could cause a panic when concurrently performing read and write transactions,
  when `debug_assertions` were enabled
* Optimize `retain()` and `retain_in()` to use less space in the database file
* Improve handling of some internal errors to return `LockPoisoned` instead of panicking

## 2.4.0 - 2024-12-30
* Add `Database::cache_stats()`
* Fix `open()` and `create()` to return `InvalidData` when they are called on a database file
  that is not a valid redb database
* Significantly speed up `restore_savepoint()`. The time is takes now scales with the change delta
  since the savepoint was captured, rather than the size of the database file
* `DatabaseStats::fragmented_bytes()` is now more accurate

## 2.3.0 - 2024-12-10
* Add `WriteTransaction::set_two_phase_commit()`
* Add `WriteTransaction::set_quick_repair()` which enables a faster repair mechanism at the cost of
  slower transaction commits
* `Durability::Paranoid` is now deprecated. Use `set_two_phase_commit(true)` instead
* Fix various bugs when repairing the database after an unclean shutdown. These could result in
  panics, leaked space in the database file, or database corruption

## 2.2.0 - 2024-10-27
* Implement `TableHandle` for `ReadOnlyTable`
* Fix bug in write cache, which caused pages to be evicted randomly. Pages are now evicted based on
  how recently they have been accessed

## 2.1.4 - 2024-10-10
* Optimize `first()` and `last()` to be almost 2x faster
* Improve in-memory cache algorithm to resolve edge cases where certain pages could become
  uncacheable under cache pressure
* Fix bug in read cache where the read cache could become disabled. This was likely to occur in
  multithreaded workloads when the read cache was smaller than the database file. This bug lead to
  5-10x performance degradations for some workloads

## 2.1.3 - 2024-09-14
* Significant performance optimizations to `compact()`
* Fix some additional cases where `compact()` did not fully compact the database
* Fix a panic that could occur in `commit()` or `abort()` after an IO error. `StorageError::PreviousIo` is now returned
* Fix a potential panic that could occur when repairing the database after a crash

## 2.1.2 - 2024-08-25
### Major fixes:
* Fix leak of database space that could occur when calling `restore_savepoint()`
* Fix leak of database space when calling `delete_multimap_table()`
* Fix database corruption which could occur when restoring a savepoint. This edge case is rare,
  and could only occur if the database was less than approximately 4TiB when the savepoint was
  created, and greater than 4TiB when the savepoint was restored
* Fix edge case where a transient I/O error that occurred during transaction commit, but then did
  not reoccur when the `Database` was dropped, could cause database corruption

**Important: If your application has called `restore_savepoint()`, `delete_multimap_table()`,
or you suspect it may have experienced a transient I/O error during transaction commit.
It is recommended that you run `check_integrity()` after upgrading to this version.
This will both detect corruption and clean up any leaked space.**

### Other changes and fixes:
* Optimize page freeing to reduce the size of the database file
* Fix several cases where `check_integrity()` would return `Ok(false)` instead of `Ok(true)`
* Fix some cases where `compact()` did not fully compact the database
* Make the metadata overhead returned by `WriteTransaction::stats()` more accurate
* Return `StorageError::ValueTooLarge` when a key-value pair exceeds a total of 3.75GiB.
  Previously, a panic would occur for key-value pairs that were approximately 4GiB.
* Downgrade several `info!` log messages to `debug!`
* Improve documentation

## 2.1.1 - 2024-06-09
* Fix panic that occurred when calling `compact()` when a read transaction was in progress
* Fix `ReadTransaction::close()` to return `Ok` when it succeeds
* Performance optimizations

## 2.1.0 - 2024-04-20
* Implement `Key` and `Value` for `String`
* Allow users to implement `ReadableTableMetadata`, `ReadableTable`, and `ReadableMultimapTable`

## 2.0.0 - 2024-03-22

### Major file format change
2.0.0 uses a new file format that optimizes `len()` to be constant time. This means that it is not
backwards compatible with 1.x. To upgrade, consider using a pattern like that shown in the
[upgrade_v1_to_v2](https://github.com/cberner/redb/blob/222a37f4600588261b0983eebcd074bb69d6e5a0/tests/backward_compatibility.rs#L282-L299) test.

### Other changes
* `check_integrity()` now returns a `DatabaseError` instead of a `StorageError`
* Table metadata methods have moved to a new `ReadableTableMetadata` trait
* Rename `RedbKey` to `Key`
* Rename `RedbValue` to `Value`
* Remove lifetimes from read-only tables
* Remove lifetime from `WriteTransaction` and `ReadTransaction`
* Remove `drain()` and `drain_filter()` from `Table`. Use `retain`, `retain_in`, `extract_if` or `extract_from_if` instead
* impl `Clone` for `Range`
* Add support for `[T;N]` as a `Value` or `Key` as appropriate for the type `T`
* Add `len()` and `is_empty()` to `MultimapValue`
* Add `retain()` and `retain_in()` to `Table`
* Add `extract_if()` and `extract_from_if()` to `Table`
* Add `range()` returning a `Range` with the `'static` lifetime to read-only tables
* Add `get()` returning a range with the `'static` lifetime to read-only tables
* Add `close()` method to `ReadTransaction`

## 1.5.1 - 2024-03-16
* Fix `check_integrity()` so that it returns `Ok(true)` when no repairs were preformed. Previously,
  it returned `Ok(false)`

## 1.5.0 - 2024-01-15
* Export `TableStats` type
* Export `MutInPlaceValue` which allows custom types to support `insert_reserve()`
* Add untyped table API which allows metadata, such as table stats, to be retrieved for at table
  without knowing its type at compile time
* Fix compilation on uncommon platforms (those other than Unix and Windows)

## 1.4.0 - 2023-11-21
* Add `Builder::set_repair_callback()` which can be used to set a callback function that will be invoked if the database needs repair while opening it.
* Add support for custom storage backends. This is done by implementing the `StorageBackend` trait and
  using the `Builder::create_with_backend` function. This allows the database to be stored in a location other
  than the filesystem
* Implement `RedbKey` and `RedbValue` for `char`
* Implement `RedbKey` and `RedbValue` for `bool`
* Implement `TableHandle` for `Table`
* Implement `MultimapTableHandle` for `MultimapTable`
* Fix panic that could occur when inserting a large number of fixed width values into a table within a single transaction
* Fix panic when calling `delete_table()` on a table that is already open
* Improve performance for fixed width types
* Support additional platforms

## 1.3.0 - 2023-10-22
* Implement `RedbKey` for `Option<T>`
* Implement `RedbValue` for `Vec<T>`
* Implement `Debug` for tables
* Add `ReadableTable::first()` and `last()` which retrieve the first and last key-value pairs, respectively`
* Reduce lock contention for mixed read-write workloads
* Documentation improvements

## 1.2.0 - 2023-09-24
* Add `Builder::create_file()` which does the same thing as `create()` but
  takes a `File` instead of a path
* Add `stats()` to tables which provides informational statistics on the table's storage
* Fix `WriteTransaction::stats()` to correctly count the storage used by multi-map tables
* Fix panics that could occur when operating on savepoints concurrently from multiple threads
  on the same `WriteTransaction`
* Implement `Send` for `WriteTransaction`
* Change MSRV to 1.66
* Performance optimizations

## 1.1.0 - 2023-08-20
* Fix panic when calling `compact()` on certain databases
* Fix panic when calling `compact()` when an ephemeral `Savepoint` existed
* Improve performance of `compact()`
* Relax lifetime requirements on arguments to `insert()`

## 1.0.5 - 2023-07-16
* Fix a rare panic when recovering a database file after a crash
* Minor performance improvement to write heavy workloads

## 1.0.4 - 2023-07-01
* Fix serious data corruption issue when calling `drain()` or `drain_filter()` on a `Table` that had
  uncommitted data

## 1.0.3 - 2023-06-30
* Fix panic when re-opening databases of certain, small, sizes

## 1.0.2 - 2023-06-29
* Fix panic when recovering some databases after a forceful shutdown
* Fix panic when recovering databases with multimaps that have fixed width values after a forceful shutdown

## 1.0.1 - 2023-06-26
* Fix panic that could occur after an IO error when reopening a database
* Fix panic that could occur after an IO error when opening a table
* Improve error message when opening a table twice to include a more meaningful line number
* Performance improvements

## 1.0.0 - 2023-06-16
### Announcement
redb has reached its first stable release! The file format is now gauranteed to be backward compatible,
and the API is stable. I've run pretty extensive fuzz testing, but please report any bugs you encounter.

The following features are complete:
* MVCC with a single `WriteTransaction` and multiple `ReadTransaction`s
* Zero-copy reads
* ACID semantics, including non-durable transactions which only sacrifice Durability
* Savepoints which allow the state of the database to be captured and restored later

#### Changes from 0.22.0:
* Stabilize file format
* Improve performance of `restore_savepoint()`

## 0.22.0 - 2023-06-12
* Fix panic while repairing a database file after crash
* Fix rare panic in `restore_savepoint()`

## 0.21.0 - 2023-06-09
* Improve cache heuristic. This asymptotically improves performance on large databases. Benchmarks show 30% to 5x+
* Fix rare crash that could occur under certain conditions when inserting values > 2GiB
* Fix crash when growing database beyond 4TiB
* Fix panic when repairing a database containing a multimap table with fixed width values
* Performance optimizations
* File format simplifications

## 0.20.0 - 2023-05-30
* Export `TransactionError` and `CommitError`. These were unintentionally private
* Implement `std::error::Error` for all error enums

## 0.19.0 - 2023-05-29
* Remove `Clone` bound from range argument type on `drain()` and `drain_filter()`
* File format changes to improve future extensibility

## 0.18.0 - 2023-05-28
* Improve errors to be more granular. `Error` has been split into multiple different `enum`s, which
  can all be implicitly converted back to `Error` for convenience
* Rename `savepoint()` to `ephemeral_savepoint()`
* Add support for persistent savepoints. These persist across database restarts and must be explicitly
  released
* Optimize `restore_savepoint()` to be ~30x faster
* Add experimental support for WASI. This requires nightly
* Implement `RedbKey` for `()`
* Fix some rare crash and data corruption bugs

## 0.17.0 - 2023-05-09
* Enforce a limit of 3GiB on keys & values
* Fix database corruption bug that could occur if a `Durability::None` commit was made,
  followed by a durable commit and the durable commit crashed or encountered an I/O error during `commit()`
* Fix panic when re-openning a database file, when the process that last had it open had crashed
* Fix several bugs where an I/O error during `commit()` could cause a panic instead of returning an `Err`
* Change `length` argument to `insert_reserve()` to `u32`
* Change `Table::len()` to return `u64`
* Change width of most fields in `DatabaseStats` to `u64`
* Remove `K` type parameter from `AccessGuardMut`
* Add `Database::compact()` which compacts the database file
* Performance optimizations

## 0.16.0 - 2023-04-28
* Combine `Builder::set_read_cache_size()` and `Builder::set_write_cache_size()` into a single,
  `Builder::set_cache_size()` setting
* Relax lifetime constraints on read methods on tables
* Optimizations to `Savepoint`

## 0.15.0 - 2023-04-09
* Add `Database::check_integrity()` to explicitly run repair process (it is still always run if needed on db open)
* Change `list_tables()` to return a `TableHandle`
* Change `delete_table()` to take a `TableHandle`
* Make `insert_reserve()` API signature type safe
* Change all iterators to return `Result` and propagate I/O errors
* Replace `WriteStrategy` with `Durability::Paranoid`
* Remove `Builder::set_initial_size()`
* Enable db file shrinking on Windows
* Performance optimizations

## 0.14.0 - 2023-03-26
* Remove `Builder::create_mmapped()` and `Builder::open_mmapped()`. The mmap backend has been removed
  because it was infeasible to prove that it was sound. This makes the redb API entirely safe,
  and the remaining `File` based backed is within a factor of ~2x on all workloads that I've benchmarked
* Make `Table` implement `Send`. It is now possible to insert into multiple `Table`s concurrently
* Expose `AccessGuardMut`, `Drain` and `DrainFilter` in the public API
* Rename `RangeIter` to `Range`
* Rename`MultimapRangeIter` to `MultimapRange`
* Rename `MultimapValueIter` to `MultimapValue`
* Performance optimizations

## 0.13.0 - 2023-02-05
* Fix a major data corruption issue that was introduced in version 0.12.0. It caused databases
  greater than ~4GB to become irrecoverably corrupted due to an integer overflow in `PageNumber::address_range`
  that was introduced by commit `b2c44a824d1ba69f526a1a75c56ae8484bae7248`
* Add `drain_filter()` to `Table`
* Make key and value type bounds more clear for tables

## 0.12.1 - 2023-01-22
* Fix `open()` on platforms with OS page size != 4KiB
* Relax lifetime requirements on argument to `range()` and `drain()`

## 0.12.0 - 2023-01-21
* Add `pop_first()` and `pop_last()` to `Table`
* Add `drain()` to `Table`
* Add support for `Option<T>` as a value type
* Add support for user defined key and value types. Users must implement `RedbKey` and/or `RedbValue`
* Change `get()`, `insert()`, `remove()`...etc to take arguments of type `impl Borrow<SelfType>`
* Return `Error::UpgradeRequired` when opening a file with an outdated file format
* Improve support for 32bit platforms
* Performance optimizations

## 0.11.0 - 2022-12-26
* Remove `[u8]` and `str` type support. Use `&[u8]` and `&str` instead.
* Change `get()`, `range()` and several other methods to return `AccessGuard`.
* Rename `AccessGuard::to_value()` to `value()`
* Add a non-mmap based backend which is now the default. This makes `Database::create()` and
  `Database::open()` safe, but has worse performance in some cases. The mmap backend is available
  via `create_mmapped()`/`open_mmapped()`. There is no difference in the file format, so applications
  can switch from one backend to the other.
* Better handling of fsync failures

## 0.10.0 - 2022-11-23
* Remove maximum database size argument from `create()`. Databases are now unbounded in size
* Reduce address space usage on Windows
* Remove `set_dynamic_growth()`
* Add `set_initial_size()` to `Builder`
* Optimize cleanup of deleted pages. This resolves a performance issue where openning a Database
  or performing a small transaction, could be slow if the last committed transaction deleted a large
  number of pages
* Remove `set_page_size()`. 4kB pages are always used now
* Add `iter()` method to `Table` and `MultimapTable`
* Fix various lifetime issues with type that had a lifetime, such as `&str` and `(&[u8], u64)`

## 0.9.0 - 2022-11-05
* Add support for dynamic file growth on Windows
* Add support for tuple types as keys and values
* Remove `Builder::set_region_size`
* Save lifetime from `Savepoint`
* Fix crash when using `create()` to open an existing database created with `WriteStrategy::TwoPhase`
* Fix rare crash when writing a mix of small and very large values into the same table
* Performance optimizations

## 0.8.0 - 2022-10-18
* Performance improvements for database files that are too large to fit in RAM
* Fix deadlock in concurrent calls to `savepoint()` and `restore_savepoint()`
* Fix crash if `restore_savepoint()` failed
* Move `savepoint()` and `restore_savepoint()` methods to `WriteTransaction`
* Implement `Iterator` for the types returned from `range()` and `remove_all()`

## 0.7.0 - 2022-09-25
* Add support for Windows
* Add `Database::set_write_strategy` which allows the `WriteStrategy` of the database to be changed after creation
* Make `Database::begin_write` block, instead of panic'ing, if there is another write already in progress
* Add `Database::savepoint` and `Database::restore_savepoint` which can be used to snapshot and rollback the database
* Rename `DatabaseBuilder` to `Builder`
* Performance optimizations for large databases

## 0.6.1 - 2022-09-11
* Fix crash when `Database::open()` was called on a database that had been created with `WriteStrategy::TwoPhase`
* Change default region size on 32bit platforms to 4GiB

## 0.6.0 - 2022-09-10
* Return `Err` instead of panic'ing when opening a database file with an incompatible file format version
* Many optimizations to the file format, and progress toward stabilizing it
* Fix race between read & write transactions, which could cause reads to return corrupted data
* Better document the different `WriteStrategy`s
* Fix panic when recovering a database that was uncleanly shutdown, which had been created with `WriteStrategy::Checksum` (which is the default)
* Fix panic when using `insert_reserve()` in certain cases

## 0.5.0 - 2022-08-06
* Optimize `MultimapTable` storage format to use `O(k * log(n_k) + v * log(n_v / n_k))` space instead of `O(k * log(n_k + n_v) + v * log(n_k + n_v))` space,
  where k is the size of the stored keys, v is the size of the stored values, n_k is the number of stored keys,
  n_v is the number of stored values
* Fix compilation errors for 32bit x86 targets
* Add support for the unit type, `()`, as a value
* Return an error when attempting to open the same database file for writing in multiple locations, concurrently
* More robust handling of fsync failures
* Change `MultimapTable::range` to return an iterator of key-value-collection pairs, instead of key-value pairs
* Automatically abort `WriteTransaction` on drop

## 0.4.0 - 2022-07-26
* Add single phase with checksum commit strategy. This is now the default and reduces commit latency by ~2x. For more details,
  see the [design doc](docs/design.md#1-phase--checksum-durable-commits) and
  [blog post](https://www.redb.org/post/2022/07/26/faster-commits-with-1pcc-instead-of-2pc/). The previous behavior is available
  via `WriteStrategy::Throughput`, and can have better performance when writing a large number of bytes per transaction.

## 0.3.1 - 2022-07-20
* Fix a bug where re-opening a `Table` during a `WriteTransaction` lead to stale results being read

## 0.3.0 - 2022-07-19
* Fix a serious data corruption issue that caused many write operations to corrupt the database
* Make redb region size configurable
* Implement garbage collection of empty regions
* Fixes and optimizations to make the file format more efficient

## 0.2.0 - 2022-06-10
* Add information log messages which can be enabled with the `logging` feature
* Add support for `[u8; N]` type
* Optimize storage of fixed width types. The value length is no longer stored, which reduces storage space by ~50% for `u64`,
  2x for `u32`, and also improves performance.

## 0.1.2 - 2022-05-08
* Change `insert()` to return an `Option<V>` with the previous value, instead of `()`

## 0.1.1 - 2022-04-24
* Improved documentation

## 0.1.0 - 2022-04-23
* Initial beta release