How RAG Works, from Documents to Answers
Understand how RAG connects documents to an LLM: build an index, retrieve passages, assemble context, and return an answer with traceable sources.
Collection
Ten articles for software engineers on how RAG systems work and fail. Follow worked examples through parsing, indexing, retrieval, context assembly, grounded answers, evaluation, and security.
Understand how RAG connects documents to an LLM: build an index, retrieve passages, assemble context, and return an answer with traceable sources.
Compare chunk boundaries on the same source, preserve qualifiers and table structure, and evaluate retrieval against stable evidence rather than arbitrary chunk IDs.
Design document ingestion around immutable representations, idempotent jobs, and atomic publication so failed updates cannot silently replace searchable evidence.
Understand vector geometry, pin the full encoding contract, and evaluate approximate search under real filters before migrating an embedding index.
Turn retrieved candidates into useful context by preserving qualifiers, tracking expansion provenance, budgeting tokens, and separating image retrieval from visual answering.
Work through reciprocal rank fusion, distinguish full-text search from BM25, and evaluate reranking and corrective retrieval without treating scores as confidence.
Translate questions into bounded retrieval plans, preserve metadata constraints, and verify SQL result semantics with a worked incident-table example.
Separate schema validity, citation identity, and factual support; design bounded repair, honest abstention, and streaming behavior around those distinct guarantees.
Separate retrieval coverage, context quality, and answer support. Calculate ranking metrics and design reproducible regression gates.
Carry authorization through retrieval, context, caches, and citations. Define trust boundaries, revocation behavior, and operational controls.