embedvec — High-Performance Embedded Vector Database

Fast, lightweight, in-process vector database with HNSW indexing, SIMD-accelerated distance calculations, metadata filtering, E8 lattice quantization, and optional persistence via Sled or RocksDB.

Why embedvec?

• Pure Rust — No C++ dependencies (unless using RocksDB), safe and portable
• Blazing Fast — AVX2/FMA SIMD acceleration, optimized HNSW with O(1) lookups
• Memory Efficient — E8 quantization provides 4-6× compression with <5% recall loss
• Flexible Persistence — Choose between Sled (pure Rust) or RocksDB (high performance)
• Production Ready — Async API, metadata filtering, batch operations

Benchmarks

768-dimensional vectors, 10k dataset, AVX2 enabled:

Run cargo bench to reproduce on your hardware.

Core Features

Quick Start — Rust

[dependencies]
embedvec = "0.5"
tokio = { version = "1.0", features = ["rt-multi-thread", "macros"] }
serde_json = "1.0"

use embedvec::{Distance, EmbedVec, FilterExpr, Quantization};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create in-memory index with E8 quantization
    let mut db = EmbedVec::builder()
        .dimension(768)
        .metric(Distance::Cosine)
        .m(32)                              // HNSW connections per layer
        .ef_construction(200)               // Build-time beam width
        .quantization(Quantization::e8_default())  // 4-6× memory savings
        .build()
        .await?;

    // Add vectors with metadata
    let vectors = vec![
        vec![0.1; 768],
        vec![0.2; 768],
    ];
    let payloads = vec![
        serde_json::json!({"doc_id": "123", "category": "finance", "timestamp": 1737400000}),
        serde_json::json!({"doc_id": "456", "category": "tech", "timestamp": 1737500000}),
    ];

    db.add_many(&vectors, payloads).await?;

    // Search with metadata filter
    let filter = FilterExpr::eq("category", "finance")
        .and(FilterExpr::gt("timestamp", 1730000000));

    let results = db.search(
        &vec![0.15; 768],  // query vector
        10,                 // k
        128,                // ef_search
        Some(filter)
    ).await?;

    for hit in results {
        println!("id: {}, score: {:.4}, payload: {:?}", hit.id, hit.score, hit.payload);
    }

    Ok(())
}

Quick Start — Python

pip install embedvec-py

import embedvec_py
import numpy as np

# Create database with E8 quantization
db = embedvec_py.EmbedVec(
    dim=768,
    metric="cosine",
    m=32,
    ef_construction=200,
    quantization="e8-10bit",  # or None, "e8-8bit", "e8-12bit"
    persist_path=None,         # or "/tmp/embedvec.db"
)

# Add vectors (numpy array or list-of-lists)
vectors = np.random.randn(50000, 768).tolist()
payloads = [{"doc_id": str(i), "tag": "news" if i % 3 == 0 else "blog"} 
            for i in range(50000)]

db.add_many(vectors, payloads)

# Search with filter
query = np.random.randn(768).tolist()
hits = db.search(
    query_vector=query,
    k=10,
    ef_search=128,
    filter={"tag": "news"}  # simple exact-match shorthand
)

for hit in hits:
    print(f"score: {hit['score']:.4f}  id: {hit['id']}  {hit['payload']}")

API Reference

EmbedVec Builder

EmbedVec::builder()
    .dimension(768)                    // Vector dimension (required)
    .metric(Distance::Cosine)          // Distance metric
    .m(32)                             // HNSW M parameter
    .ef_construction(200)              // HNSW build parameter
    .quantization(Quantization::None)  // Or E8 for compression
    .persistence("path/to/db")         // Optional disk persistence
    .build()
    .await?;

Core Operations

FilterExpr — Composable Filters

// Equality
FilterExpr::eq("category", "finance")

// Comparisons
FilterExpr::gt("timestamp", 1730000000)
FilterExpr::gte("score", 0.5)
FilterExpr::lt("price", 100)
FilterExpr::lte("count", 10)

// String operations
FilterExpr::contains("name", "test")
FilterExpr::starts_with("path", "/api")

// Membership
FilterExpr::in_values("status", vec!["active", "pending"])

// Existence
FilterExpr::exists("optional_field")

// Boolean composition
FilterExpr::eq("a", 1)
    .and(FilterExpr::eq("b", 2))
    .or(FilterExpr::not(FilterExpr::eq("c", 3)))

Quantization Modes

// No quantization (full f32)
Quantization::None

// E8 with Hadamard preprocessing (recommended)
Quantization::E8 {
    bits_per_block: 10,
    use_hadamard: true,
    random_seed: 0xcafef00d,
}

// Convenience constructor
Quantization::e8_default()  // 10-bit with Hadamard

E8 Lattice Quantization

embedvec implements state-of-the-art E8 lattice quantization based on QuIP#/NestQuant/QTIP research (2024-2025):

1. Hadamard Preprocessing: Fast Walsh-Hadamard transform + random signs makes coordinates more Gaussian/i.i.d.
2. Block-wise Quantization: Split vectors into 8D blocks, quantize each to nearest E8 lattice point
3. Asymmetric Search: Query remains FP32, database vectors decoded on-the-fly during HNSW traversal
4. Compact Storage: ~2-2.5 bits per dimension effective

Why E8?

The E8 lattice has exceptional packing density in 8 dimensions, providing better rate-distortion than scalar quantization or product quantization for normalized embeddings typical in LLM/RAG applications.

Performance

Measured Benchmarks (768-dim, 10k vectors, AVX2)

Projected Performance at Scale

Feature Flags

[dependencies]
embedvec = { version = "0.5", features = ["persistence-sled", "async"] }

Persistence Backends

embedvec supports two persistence backends:

Sled (Default)

Pure Rust embedded database. Good default for most use cases.

use embedvec::{EmbedVec, Distance, BackendConfig, BackendType};

// Simple path-based persistence (uses Sled)
let db = EmbedVec::with_persistence("/path/to/db", 768, Distance::Cosine, 32, 200).await?;

// Or via builder
let db = EmbedVec::builder()
    .dimension(768)
    .persistence("/path/to/db")
    .build()
    .await?;

RocksDB (Optional)

Higher performance LSM-tree database. Better for write-heavy workloads and large datasets.

[dependencies]
embedvec = { version = "0.5", features = ["persistence-rocksdb", "async"] }

use embedvec::{EmbedVec, Distance, BackendConfig, BackendType};

// Configure RocksDB backend
let config = BackendConfig::new("/path/to/db")
    .backend(BackendType::RocksDb)
    .cache_size(256 * 1024 * 1024);  // 256MB cache

let db = EmbedVec::with_backend(config, 768, Distance::Cosine, 32, 200).await?;

Testing

# Run all tests
cargo test

# Run with specific features
cargo test --features "persistence"

# Run benchmarks
cargo bench

Benchmarking

# Install criterion
cargo install cargo-criterion

# Run benchmarks
cargo criterion

# Memory profiling (requires jemalloc)
cargo bench --features "jemalloc"

Roadmap

• v0.5 (current): E8 quantization stable + persistence
• v0.6: Binary/PQ fallback, delete support, batch queries
• v0.7: LangChain/LlamaIndex official integration
• Future: Hybrid sparse-dense, full-text + vector

License

MIT OR Apache-2.0

Contributing

Contributions welcome! Please read CONTRIBUTING.md before submitting PRs.

Acknowledgments

• HNSW algorithm: Malkov & Yashunin (2016)
• E8 quantization: Inspired by QuIP#, NestQuant, QTIP (2024-2025)
• Rust ecosystem: serde, tokio, pyo3, sled

embedvec — The "SQLite of vector search" for Rust-first teams in 2026.