mappedbptree

A persistent, memory-mapped B+tree for Rust with a BTreeMap-like API.

Built by Claude.

Features

• File-backed storage via mmap — data survives process restarts
• Thread-safe: multiple concurrent readers, exclusive writers (RwLock)
• Zero-copy access to keys and values via bytemuck::Pod
• Full B+tree operations: insert, get, remove, iter, range, clear
• Auto-tuned node capacity based on system page size (4096 bytes)

Constraints

Keys (K: Ord + Pod) and values (V: Pod) must be plain-data types — fixed-size, no heap allocations. Integers, arrays, and #[repr(C)] structs work; String and Vec do not.

Quick start

[dependencies]
mappedbptree = "0.1"

use mappedbptree::MmapBTreeBuilder;

let tree = MmapBTreeBuilder::<i32, u64>::new()
    .path("data.db")
    .build()?;

tree.insert(1, 100)?;
assert_eq!(tree.get(&1)?, Some(100));

tree.remove(&1)?;

for (k, v) in tree.range(0..50)? {
    println!("{k}: {v}");
}

License

MIT