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Vector Database

An HNSW-based in-memory vector database in Rust with configurable distance metrics, quantization, segmented indexing, and concurrent search.

November 2025 • Rust, HNSW, Rayon, Memory Mapping

Problem

Similarity search systems need low-latency nearest-neighbor retrieval while balancing memory efficiency, persistence, and concurrent access.

Approach

I implemented an HNSW-powered vector engine with L2 and cosine metrics, scalar quantization, and memory-mapped fixed-capacity storage. The index model combines immutable and mutable segments with flush support, while search is parallelized with Rayon.

Outcome

  • Delivered thread-safe concurrent search with persistent JSON-backed state.
  • Added segmented index architecture to support mutable ingestion and stable query behavior.
  • Built a configurable vector search foundation suitable for retrieval-heavy workloads.