Introduction

When designing a RAG (Retrieval-Augmented Generation) system, understanding what's happening inside vector search lets you tune the trade-offs between accuracy, speed, and cost yourself.

This article covers the fundamentals of vector search:

ANN search (Approximate Nearest Neighbor) and HNSW (Hierarchical Navigable Small World)

Similarity and distance metrics (cosine similarity, dot product, L2 distance)