RAG Mechanics: Embeddings and Search

The machinery under retrieval: embedding models, chunking, approximate nearest-neighbor search, and hybrid ranking.

Content last verified 2026-09.

Lessons

1. The Retrieval Idea
2. Embedding Models
3. Chunking
4. Vector Search and Hybrid Ranking

Sources

• Reimers & Gurevych (2019) — Sentence-BERT: Sentence Embeddings using Siamese BERT-Networks
• Karpukhin et al. (2020) — Dense Passage Retrieval for Open-Domain Question Answering
• Lewis et al. (2020) — Retrieval-Augmented Generation for Knowledge-Intensive NLP Tasks
• Malkov & Yashunin (2016) — Efficient and Robust Approximate Nearest Neighbor Search Using Hierarchical Navigable Small World Graphs