ruvector/docs/guide/ADVANCED_FEATURES.md

Advanced Features Guide

This guide covers advanced features of Ruvector including hybrid search, filtered search, MMR, quantization techniques, and performance optimization.

Table of Contents

1. Hybrid Search (Vector + Keyword)
2. Filtered Search
3. MMR (Maximal Marginal Relevance)
4. Product Quantization
5. Conformal Prediction
6. Performance Optimization

Hybrid Search

Combine vector similarity with keyword-based BM25 scoring for best of both worlds.

Rust

use ruvector_core::{HybridSearch, HybridConfig};

fn hybrid_search_example(db: &VectorDB) -> Result<(), Box<dyn std::error::Error>> {
    let config = HybridConfig {
        vector_weight: 0.7,  // 70% vector similarity
        bm25_weight: 0.3,    // 30% keyword relevance
        k1: 1.5,             // BM25 parameter
        b: 0.75,             // BM25 parameter
    };

    let hybrid = HybridSearch::new(db, config)?;

    // Search with both vector and keywords
    let results = hybrid.search(
        &query_vector,
        &["machine", "learning", "embeddings"],
        10
    )?;

    for result in results {
        println!(
            "ID: {}, Vector Score: {:.4}, BM25 Score: {:.4}, Combined: {:.4}",
            result.id, result.vector_score, result.bm25_score, result.combined_score
        );
    }

    Ok(())
}

Node.js

const { HybridSearch } = require('ruvector');

const hybrid = new HybridSearch(db, {
    vectorWeight: 0.7,
    bm25Weight: 0.3,
    k1: 1.5,
    b: 0.75
});

const results = await hybrid.search(
    queryVector,
    ['machine', 'learning', 'embeddings'],
    10
);

results.forEach(result => {
    console.log(`ID: ${result.id}`);
    console.log(`  Vector: ${result.vectorScore.toFixed(4)}`);
    console.log(`  BM25: ${result.bm25Score.toFixed(4)}`);
    console.log(`  Combined: ${result.combinedScore.toFixed(4)}`);
});

Use Cases

• Document search: Combine semantic similarity with keyword matching
• E-commerce: Vector similarity for visual features + text search for descriptions
• Q&A systems: Semantic understanding + exact term matching

Filtered Search

Apply metadata filters before or after vector search.

Pre-filtering

Apply filters before graph traversal (efficient for selective filters).

use ruvector_core::{FilteredSearch, FilterExpression, FilterStrategy};
use serde_json::json;

fn pre_filtering_example(db: &VectorDB) -> Result<(), Box<dyn std::error::Error>> {
    let filter = FilterExpression::And(vec![
        FilterExpression::Eq("category".to_string(), json!("tech")),
        FilterExpression::Gte("timestamp".to_string(), json!(1640000000)),
    ]);

    let filtered = FilteredSearch::new(db, FilterStrategy::PreFilter);

    let results = filtered.search(&query_vector, 10, Some(filter))?;

    Ok(())
}

Post-filtering

Traverse full graph, then apply filters (better for loose constraints).

let filtered = FilteredSearch::new(db, FilterStrategy::PostFilter);

let filter = FilterExpression::In(
    "tags".to_string(),
    vec![json!("ml"), json!("ai")]
);

let results = filtered.search(&query_vector, 10, Some(filter))?;

Filter Expressions

// Equality
FilterExpression::Eq("status".into(), json!("active"))

// Comparison
FilterExpression::Gt("score".into(), json!(0.8))
FilterExpression::Gte("timestamp".into(), json!(start_time))
FilterExpression::Lt("price".into(), json!(100))
FilterExpression::Lte("rating".into(), json!(5))

// Set operations
FilterExpression::In("category".into(), vec![json!("a"), json!("b")])
FilterExpression::Nin("id".into(), vec![json!("exclude1"), json!("exclude2")])

// Logical operators
FilterExpression::And(vec![expr1, expr2])
FilterExpression::Or(vec![expr1, expr2])
FilterExpression::Not(Box::new(expr))

Node.js

const { FilteredSearch } = require('ruvector');

const filtered = new FilteredSearch(db, 'preFilter');

const results = await filtered.search(queryVector, 10, {
    and: [
        { field: 'category', op: 'eq', value: 'tech' },
        { field: 'timestamp', op: 'gte', value: 1640000000 }
    ]
});

MMR (Maximal Marginal Relevance)

Diversify search results to reduce redundancy.

Rust

use ruvector_core::{MMRSearch, MMRConfig};

fn mmr_example(db: &VectorDB) -> Result<(), Box<dyn std::error::Error>> {
    let config = MMRConfig {
        lambda: 0.5,        // Balance relevance (1.0) vs diversity (0.0)
        diversity_weight: 0.3,
    };

    let mmr = MMRSearch::new(db, config)?;

    // Get diverse results
    let results = mmr.search(&query_vector, 20)?;

    println!("Diverse results (λ = 0.5):");
    for (i, result) in results.iter().enumerate() {
        println!("{}. ID: {}, Relevance: {:.4}", i + 1, result.id, result.score);
    }

    Ok(())
}

Lambda Parameter

• λ = 1.0: Pure relevance (no diversity)
• λ = 0.5: Balanced (recommended)
• λ = 0.0: Pure diversity (may sacrifice relevance)

Node.js

const { MMRSearch } = require('ruvector');

const mmr = new MMRSearch(db, {
    lambda: 0.5,
    diversityWeight: 0.3
});

const results = await mmr.search(queryVector, 20);

Use Cases

• Recommendation systems: Avoid showing too many similar items
• Document retrieval: Diverse perspectives on a topic
• Search results: Reduce redundancy in top results

Product Quantization

Achieve 8-16x memory compression with 90-95% recall.

Rust

use ruvector_core::{EnhancedPQ, PQConfig};

fn product_quantization_example() -> Result<(), Box<dyn std::error::Error>> {
    let mut options = DbOptions::default();
    options.dimensions = 128;
    options.quantization = QuantizationConfig::Product {
        subspaces: 16,  // Split into 16 subvectors of 8D each
        k: 256,         // 256 centroids per subspace
    };

    let db = VectorDB::new(options)?;

    // Insert vectors (automatically quantized)
    db.insert_batch(vectors)?;

    // Search uses quantized vectors
    let results = db.search(&query)?;

    Ok(())
}

Configuration

Subspaces	Dimensions per subspace	Compression	Recall
8	16	8x	92-95%
16	8	16x	90-94%
32	4	32x	85-90%

Node.js

const db = new VectorDB({
    dimensions: 128,
    quantization: {
        type: 'product',
        subspaces: 16,
        k: 256
    }
});

Performance Impact

Without PQ: 1M vectors × 128 dims × 4 bytes = 512 MB
With PQ (16 subspaces): 1M vectors × 16 bytes = 16 MB (32x compression)
+ Codebooks: 16 × 256 × 8 × 4 bytes = 128 KB
Total: ~16.1 MB

Conformal Prediction

Get confidence intervals for predictions.

Rust

use ruvector_core::{ConformalPredictor, ConformalConfig, PredictionSet};

fn conformal_prediction_example() -> Result<(), Box<dyn std::error::Error>> {
    let config = ConformalConfig {
        alpha: 0.1,              // 90% confidence
        calibration_size: 1000,  // Calibration set size
    };

    let mut predictor = ConformalPredictor::new(config);

    // Calibrate with known similarities
    let calibration_data: Vec<(Vec<f32>, Vec<f32>, f64)> = get_calibration_data();
    predictor.calibrate(&calibration_data)?;

    // Predict with confidence
    let prediction: PredictionSet = predictor.predict(&query_vector, &db)?;

    println!("Prediction set size: {}", prediction.candidates.len());
    println!("Confidence level: {:.1}%", (1.0 - config.alpha) * 100.0);

    for candidate in prediction.candidates {
        println!(
            "  ID: {}, Distance: {:.4}, Confidence: [{:.4}, {:.4}]",
            candidate.id,
            candidate.distance,
            candidate.confidence_lower,
            candidate.confidence_upper
        );
    }

    Ok(())
}

Node.js

const { ConformalPredictor } = require('ruvector');

const predictor = new ConformalPredictor({
    alpha: 0.1,           // 90% confidence
    calibrationSize: 1000
});

// Calibrate
await predictor.calibrate(calibrationData);

// Predict with confidence
const prediction = await predictor.predict(queryVector, db);

console.log(`Prediction set size: ${prediction.candidates.length}`);
prediction.candidates.forEach(c => {
    console.log(`ID: ${c.id}, Distance: ${c.distance.toFixed(4)}`);
    console.log(`  Confidence: [${c.confidenceLower.toFixed(4)}, ${c.confidenceUpper.toFixed(4)}]`);
});

Use Cases

• Adaptive top-k: Dynamically adjust number of results based on confidence
• Query routing: Route uncertain queries to expensive rerankers
• Trust scores: Provide confidence metrics to users

Performance Optimization

1. SIMD Optimization

# Enable all SIMD instructions for your CPU
RUSTFLAGS="-C target-cpu=native" cargo build --release

# Specific features
RUSTFLAGS="-C target-feature=+avx2,+fma" cargo build --release

# Verify SIMD is enabled
cargo build --release -vv | grep target-cpu

2. Memory-Mapped Vectors

let mut options = DbOptions::default();
options.mmap_vectors = true;  // Enable memory mapping

let db = VectorDB::new(options)?;

Benefits:

• Instant loading (no deserialization)
• Datasets larger than RAM
• OS-managed caching

3. Batch Operations

// ❌ Slow: Individual inserts
for entry in entries {
    db.insert(entry)?;  // Many individual operations
}

// ✅ Fast: Batch insert
db.insert_batch(entries)?;  // Single optimized operation

Performance: 10-100x faster for large batches.

4. Parallel Search

use rayon::prelude::*;

let queries: Vec<Vec<f32>> = get_query_vectors();

let results: Vec<Vec<SearchResult>> = queries
    .par_iter()
    .map(|query| {
        db.search(&SearchQuery {
            vector: query.clone(),
            k: 10,
            filter: None,
            include_vectors: false,
        }).unwrap()
    })
    .collect();

5. HNSW Parameter Tuning

// For speed (lower recall)
options.hnsw.ef_search = 50;

// For accuracy (slower)
options.hnsw.ef_search = 500;

// Balanced (recommended)
options.hnsw.ef_search = 100;

6. Quantization

// 4x compression, 97-99% recall
options.quantization = QuantizationConfig::Scalar;

// 16x compression, 90-95% recall
options.quantization = QuantizationConfig::Product {
    subspaces: 16,
    k: 256,
};

7. Distance Metric Selection

// For normalized embeddings (faster)
options.distance_metric = DistanceMetric::DotProduct;

// For unnormalized embeddings
options.distance_metric = DistanceMetric::Cosine;  // Auto-normalizes

// For general similarity
options.distance_metric = DistanceMetric::Euclidean;

Performance Comparison

Configuration	Memory	Latency	Recall
Full precision, ef=50	100%	0.5ms	85%
Full precision, ef=100	100%	1.0ms	95%
Full precision, ef=500	100%	5.0ms	99%
Scalar quant, ef=100	25%	0.8ms	94%
Product quant, ef=100	6%	1.2ms	92%

Complete Advanced Example

use ruvector_core::*;

fn advanced_demo() -> Result<(), Box<dyn std::error::Error>> {
    // Create high-performance database
    let mut options = DbOptions::default();
    options.dimensions = 384;
    options.storage_path = "./advanced_db.db".to_string();
    options.hnsw = HnswConfig {
        m: 64,
        ef_construction: 400,
        ef_search: 200,
        max_elements: 10_000_000,
    };
    options.distance_metric = DistanceMetric::Cosine;
    options.quantization = QuantizationConfig::Product {
        subspaces: 16,
        k: 256,
    };
    options.mmap_vectors = true;

    let db = VectorDB::new(options)?;

    // Hybrid search with filtering
    let hybrid_config = HybridConfig {
        vector_weight: 0.7,
        bm25_weight: 0.3,
        k1: 1.5,
        b: 0.75,
    };
    let hybrid = HybridSearch::new(&db, hybrid_config)?;

    let filter = FilterExpression::And(vec![
        FilterExpression::Eq("category".into(), json!("research")),
        FilterExpression::Gte("year".into(), json!(2020)),
    ]);

    // Search with all features
    let results = hybrid.search_filtered(
        &query_vector,
        &["neural", "networks"],
        20,
        Some(filter)
    )?;

    // Apply MMR for diversity
    let mmr_config = MMRConfig {
        lambda: 0.6,
        diversity_weight: 0.4,
    };
    let diverse_results = MMRSearch::rerank(&results, mmr_config)?;

    // Conformal prediction for confidence
    let mut predictor = ConformalPredictor::new(ConformalConfig {
        alpha: 0.1,
        calibration_size: 1000,
    });
    predictor.calibrate(&calibration_data)?;
    let prediction = predictor.predict_batch(&diverse_results)?;

    // Display results with confidence
    for (i, result) in prediction.candidates.iter().enumerate() {
        println!("{}. ID: {} (confidence: {:.1}%)",
            i + 1,
            result.id,
            result.mean_confidence * 100.0
        );
    }

    Ok(())
}

Best Practices

1. Start simple: Begin with default settings, optimize later
2. Measure first: Profile before optimizing
3. Batch operations: Always use batch methods for bulk operations
4. Choose quantization wisely: Scalar for general use, product for extreme scale
5. Tune HNSW gradually: Increase parameters only if needed
6. Use appropriate metrics: Cosine for normalized, Euclidean otherwise
7. Enable SIMD: Always compile with target-cpu=native
8. Memory-map large datasets: Essential for datasets > RAM

Next Steps

• AgenticDB Tutorial - Advanced AI agent features
• Performance Tuning - Detailed optimization
• API Reference - Complete API documentation
• Examples - Working code examples