RAG Explained: Why Your AI Gets Your Own Docs Wrong

Your AI had your documents and still answered wrong. Often it's not the model, it's the search before it. https://dataforall.dev/en/architectur... RAG (retrieval-augmented generation), walked end to end with the guide's own diagrams: filing documents ahead of time (parse, chunk, embed, index) and answering one question (rewrite, search, re-rank, prompt, model); whether you need RAG at all (Anthropic's guidance: under about 200K tokens, put it all in the prompt); building it up one piece at a time; how to chunk your documents; hybrid search (meaning + BM25); where to look when an answer is wrong (retrieval, ranking, freshness, then generation); measuring retrieval separately from the answer with a golden set; and two real-world stories: Uber's Genie (lost tables and vague queries, fixed in parsing, query rewriting and hybrid search) and Anthropic's contextual retrieval test (top-20 misses from 5.7% to 1.9% on its own data). The prompt builder is our simplification; every number comes from the sources below. Every diagram, clickable, with sources, free (sign up): https://dataforall.dev/en/architectur... Sources: Lewis et al. — Retrieval-Augmented Generation for Knowledge-Intensive NLP Tasks (NeurIPS 2020); Anthropic — Introducing Contextual Retrieval (2024); OpenAI API docs — Retrieval and file search; Liu et al. — Lost in the Middle: How Language Models Use Long Contexts (2023); Xu et al. (LinkedIn) — Retrieval-Augmented Generation with Knowledge Graphs for Customer Service Question Answering (2024); Uber Engineering — Enhanced Agentic-RAG: What If Chatbots Could Deliver Near-Human Precision? (2025). Not affiliated with or endorsed by any company mentioned. #aiengineering #llm #rag #dataforall 0:00 RAG explained: how AI answers from your documents 1:07 Do you even need RAG? 1:29 Build RAG one piece at a time 1:59 How to chunk documents for RAG 2:34 Hybrid search: meaning vs keywords 2:49 Wrong answer? Check retrieval before the model 3:32 How to measure RAG: retrieval first, then answers 4:08 In the real world: Uber's Genie 4:35 In the real world: Anthropic's retrieval test 5:02 Three rules to take with you