How RAG Pipeline (Detailed) works.
A production RAG pipeline has many more components than the basic "retrieve and generate" description suggests. Here is a complete pipeline:
Ingestion phase: (1) Document loading: parse PDFs, Word docs, web pages, databases. (2) Chunking: split documents into pieces. Chunk size matters: too small loses context, too large dilutes relevance. Common: 500-1000 tokens with 100-200 token overlap. (3) Embedding: convert each chunk to a vector using an embedding model. (4) Indexing: store vectors in a vector database (Pinecone, pgvector, Weaviate).
Query phase: (1) Query embedding: convert the user's question to a vector. (2) Retrieval: find the top-K most similar chunks (typically K=5-20). (3) Reranking: use a cross-encoder model to re-score retrieved chunks by relevance (dramatically improves quality). (4) Context assembly: combine the top chunks into a prompt with the original question. (5) Generation: LLM generates an answer grounded in the retrieved context. (6) Post-processing: add citations, validate claims, format output.
Common pitfalls: wrong chunk size, no reranking (top retrieval results are often not the most relevant), ignoring metadata (filter by date, source, category before vector search), and not evaluating quality systematically.
Where it helps.
- 01Enterprise knowledge base Q&A
- 02Legal document analysis
- 03Technical support automation
- 04Academic research assistants
- 05Internal company search