Kira KV Engine

kira_kv_engine builds a static key -> id index for unique keys.

• Default MPH backend: PtrHash2025 (fast build + fast lookup)
• Optional numeric mode: PGM + MPH remap (auto_detect_numeric = true)
• Stable lookups after build: index in [0..n)

Install

[dependencies]

kira_kv_engine = ">=0.3"

Quick Start

use kira_kv_engine::IndexBuilder;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let keys = vec![
        b"user:1".to_vec(),
        b"user:2".to_vec(),
        42u64.to_le_bytes().to_vec(),
    ];

    // Default backend is PtrHash2025
    let index = IndexBuilder::new().build_index(keys)?;

    let id1 = index.lookup_str("user:1")?;
    let id2 = index.lookup_u64(42)?;

    println!("{} {}", id1, id2);
    Ok(())
}

Backends

Selectable via IndexBuilder::with_backend(...):

• BackendKind::PtrHash2025 (default)
• BackendKind::PTHash
• BackendKind::CHD
• BackendKind::RecSplit
• BackendKind::BBHash (only with bbhash feature)

Backends are selected via BackendKind; only currently supported variants are available.

Numeric Auto-Detect (PGM)

If every key is exactly 8 bytes (u64::to_le_bytes()), you can enable numeric mode:

use kira_kv_engine::IndexBuilder;

let keys: Vec<Vec<u8>> = (0..100_000u64).map(|v| v.to_le_bytes().to_vec()).collect();
let index = IndexBuilder::new()
    .auto_detect_numeric(true)
    .build_index(keys)?;
# Ok::<(), Box<dyn std::error::Error>>(())

In this mode:

• lookup_u64 is the native path
• range(min, max) returns matching index ids

Build/Perf Controls

IndexBuilder supports:

• .with_parallel_build(bool)
• .with_build_fast_profile(bool)
• .with_mph_config(...) (gamma, rehash_limit, salt)
• .with_backend(...)

Serialization

let bytes = index.to_bytes()?;
let restored = kira_kv_engine::Index::from_bytes(&bytes)?;

Benchmarks

Run:

cargo run --release --example million_build

cargo run --release --example ptrhash_bench

The benchmark outputs include:

• build time / build rate
• cold & warm lookup latency
• hit/miss ratios
• memory usage (bytes per key)

Notes

• Input keys must be unique.
• Indexes are static (rebuild on keyset change).
• Public API reference: API.md.

License

MIT