mre / sled-rs.github.io

sled

A modern embedded database. Written in Rust, usable on servers and phones from any C-compatible language.

let db = sled::open(path)?; // as in fs::open
db.insert(k, v)?;           // as in BTreeMap::insert
db.get(&k)?;                // as in BTreeMap::get
for kv in db.range(k..) {}  // as in BTreeMap::range
db.remove(&k)?;             // as in BTreeMap::remove
drop(db);                   // fsync and close file

Embedded databases are useful in several cases:

• you want to store data on disk, without facing the complexity of files
• you want to be simple, without operating an external database
• you want to be fast, without paying network costs
• using disk storage as a building block in your system

sled features

• API similar to a threadsafe BTreeMap<[u8], [u8]>
• fully serializable multi-key and multi-Tree transactions
• fully atomic single-key operations, including compare and swap and update and fetch
• zero-copy reads
• write batch support
• subscription/watch semantics on key prefixes
• multiple keyspaces
• merge operators
• forward and reverse iterators
• a crash-safe monotonic ID generator capable of generating over 100 million unique ID's per second
• zstd compression (use the compression build feature)
• cpu-scalable lock-free implementation
• SSD-optimized log-structured storage
• prefix encoded and suffix truncated keys reducing the storage cost of complex keys

references

• architectural outlook
• The Bw-Tree: A B-tree for New Hardware Platforms
• LLAMA: A Cache/Storage Subsystem for Modern Hardware
• Cicada: Dependably Fast Multi-Core In-Memory Transactions
• The Design and Implementation of a Log-Structured File System
• TinyLFU: A Highly Efficient Cache Admission Policy