Exploring the World of Vector Search: HNSW, ANN Algorithms, and Similarity Metrics

Bragadeesh Sundararajan
9 min readNov 13, 2023

Vector search, an integral concept in machine learning and data science, involves searching through a space of high-dimensional vectors to find vectors that are similar to a given query vector. This approach is crucial for handling complex and large-scale datasets where traditional search methods fall short.

Key Concepts:

Vector Search in Machine Learning and Data Science:

  • High-Dimensional Data: In machine learning, data points (like images, text, or user preferences) are often represented as high-dimensional vectors. Searching within these vectors enables efficient retrieval of similar items.
  • Applications: Common applications include recommendation systems, image and speech recognition, and natural language processing.

Hierarchical Navigable Small World (HNSW):

  • This is a graph-based algorithm designed to handle nearest neighbor searches in high-dimensional spaces. HNSW constructs a multi-layered graph where each layer is a small world graph. This structure allows for faster and more efficient searches compared to brute-force methods.

Approximate Nearest Neighbor (ANN)…

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