lsm-tree 2.10.4

A K.I.S.S. implementation of log-structured merge trees (LSM-trees/LSMTs)
Documentation 
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<p align="center">
  <img src="/logo.png" height="160">
</p>

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A K.I.S.S. implementation of log-structured merge trees (LSM-trees/LSMTs) in Rust.

> [!NOTE]
> This crate only provides a primitive LSM-tree, not a full storage engine.
> For example, it does not ship with a write-ahead log.
> You probably want to use https://github.com/fjall-rs/fjall instead.

## About

This is the most feature-rich LSM-tree implementation in Rust! It features:

- Thread-safe BTreeMap-like API
- [99.9% safe](./UNSAFE.md) & stable Rust
- Block-based tables with compression support
- Range & prefix searching with forward and reverse iteration
- Size-tiered, (concurrent) Leveled and FIFO compaction
- Multi-threaded flushing (immutable/sealed memtables)
- Partitioned block index to reduce memory footprint and keep startup time short [[1]](#footnotes)
- Block caching to keep hot data in memory
- Bloom filters to increase point lookup performance
- Snapshots (MVCC)
- Key-value separation (optional) [[2]](#footnotes)
- Single deletion tombstones ("weak" deletion)

Keys are limited to 65536 bytes, values are limited to 2^32 bytes. As is normal with any kind of storage
engine, larger keys and values have a bigger performance impact.

## Feature flags

### lz4

Allows using `LZ4` compression, powered by [`lz4_flex`](https://github.com/PSeitz/lz4_flex).

*Disabled by default.*

### miniz

Allows using `DEFLATE/zlib` compression, powered by [`miniz_oxide`](https://github.com/Frommi/miniz_oxide).

*Disabled by default.*

### bytes

Uses [`bytes`](https://github.com/tokio-rs/bytes) as the underlying `Slice` type.

*Disabled by default.*

## Stable disk format

The disk format is stable as of 1.0.0.

2.0.0 uses a new disk format and needs a manual format migration.

Future breaking changes will result in a major version bump and a migration path.

## Run unit benchmarks

```bash
cargo bench --features lz4,miniz
```

## License

All source code is licensed under MIT OR Apache-2.0.

All contributions are to be licensed as MIT OR Apache-2.0.

## Footnotes

[1] https://rocksdb.org/blog/2017/05/12/partitioned-index-filter.html

[2] https://github.com/facebook/rocksdb/wiki/BlobDB