Vector Index Tuning

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name: vector-index-tuning description: Optimize vector index performance for latency, recall, and memory. Use when tuning HNSW parameters, selecting quantization strategies, or scaling vector search infrastructure. ---

Vector Index Tuning

Guide to optimizing vector indexes for production performance.

When to Use This Skill

• Tuning HNSW parameters
• Implementing quantization
• Optimizing memory usage
• Reducing search latency
• Balancing recall vs speed
• Scaling to billions of vectors

Core Concepts

1. Index Type Selection

Data Size           Recommended Index
────────────────────────────────────────
 100M         →    IVF + PQ or DiskANN

2. HNSW Parameters

| Parameter | Default | Effect | | ------------------ | ------- | ---------------------------------------------------- | | M | 16 | Connections per node, ↑ = better recall, more memory | | efConstruction | 100 | Build quality, ↑ = better index, slower build | | efSearch | 50 | Search quality, ↑ = better recall, slower search |

3. Quantization Types

Full Precision (FP32): 4 bytes × dimensions
Half Precision (FP16): 2 bytes × dimensions
INT8 Scalar:           1 byte × dimensions
Product Quantization:  ~32-64 bytes total
Binary:                dimensions/8 bytes

Templates and detailed worked examples

Full template library and detailed worked examples live in references/details.md. Read that file when you need the concrete templates.

Best Practices

Do's

• Benchmark with real queries - Synthetic may not represent production
• Monitor recall continuously - Can degrade with data drift
• Start with defaults - Tune only when needed
• Use quantization - Significant memory savings
• Consider tiered storage - Hot/cold data separation

Don'ts

• Don't over-optimize early - Profile first
• Don't ignore build time - Index updates have cost
• Don't forget reindexing - Plan for maintenance
• Don't skip warming - Cold indexes are slow

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: svssdeva
• Source: svssdeva/agentic-skills
• License: MIT

Install and usage instructions live in the source repository linked above.