redb

A simple, portable, high-performance, ACID, embedded key-value store.

redb is written in pure Rust and is loosely inspired by lmdb. Data is stored in a collection of copy-on-write B+trees. For more details, see the design doc

use redb::{Database, Error, ReadableDatabase, TableDefinition};

const TABLE: TableDefinition<&str, u64> = TableDefinition::new("my_data");

fn main() -> Result<(), Error> {
    let db = Database::create("my_db.redb")?;
    let write_txn = db.begin_write()?;
    {
        let mut table = write_txn.open_table(TABLE)?;
        table.insert("my_key", &123)?;
    }
    write_txn.commit()?;

    let read_txn = db.begin_read()?;
    let table = read_txn.open_table(TABLE)?;
    assert_eq!(table.get("my_key")?.unwrap().value(), 123);

    Ok(())
}

Status

Stable and maintained.

The file format is stable, and a reasonable effort will be made to provide an upgrade path if there are any future changes to it.

Features

• Zero-copy, thread-safe, BTreeMap based API
• Fully ACID-compliant transactions
• MVCC support for concurrent readers & writer, without blocking
• Crash-safe by default
• Savepoints and rollbacks

no_std

Turning off the std feature, with experimental-api-5 on, builds redb without the standard library. It needs alloc, panic = "abort", and a target with atomic compare-and-swap -- Cortex-M3 and above, but not Cortex-M0. There is no filesystem, so storage is supplied by implementing StorageBackend and passing it to Builder::create_with_backend(). The cache_metrics, chrono_v0_4 and uuid features are unavailable.

Development

just and rootless podman are required. Toolchain setup, dependency vendoring, and cargo-deny checks may use network access without compiling project dependencies. Other development recipes continue to run on the host. Cargo build artifacts are cached in the redb-sandbox-target Podman volume; remove that volume to force a clean sandbox build.

Benchmarks

redb has similar performance to other top embedded key-value stores such as lmdb and rocksdb

Source code for benchmark here. Results collected on a Ryzen 9950X3D with Samsung 9100 PRO NVMe.

License

Licensed under either of

• Apache License, Version 2.0
• MIT License

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.