RAG (Retrieval-Augmented Generation) is the most impactful AI architecture pattern for enterprise use cases. It allows LLMs to answer questions based on your proprietary data — product documentation, knowledge bases, databases, and internal wikis — with far higher accuracy than vanilla LLM prompting.
But most RAG tutorials stop at the “hello world” level. This guide covers the engineering details needed for production systems.
The Basic RAG Pipeline
At its core, RAG has two phases:
Indexing (offline)
- Load documents
- Split into chunks
- Generate embeddings
- Store in vector database
Retrieval (online)
- User asks a question
- Generate query embedding
- Semantic search in vector DB
- Inject retrieved context into LLM prompt
- Return response
Chunking Strategy: The Most Underrated Decision
How you chunk your documents significantly impacts retrieval quality.
Naive Chunking (Don’t Do This)
Splitting at fixed character counts ignores document structure, splits sentences mid-thought, and loses context.
Semantic Chunking
Split at natural boundaries — paragraphs, sections, code blocks. Maintain overlap (100–200 characters) between chunks to preserve context across boundaries.
Hierarchical Chunking
Store both summary-level and detail-level chunks. Use the summary for initial retrieval, then fetch the detailed chunk for context injection.
Metadata Enrichment
Add metadata to every chunk: document title, section, author, date, document type. This enables filtered retrieval — “only search the 2025 product documentation.”
Embedding Model Selection
| Model | Dimensions | Speed | Quality | Cost |
|---|---|---|---|---|
| OpenAI text-embedding-3-large | 3072 | Medium | Excellent | $$ |
| Cohere embed-v3 | 1024 | Fast | Very Good | $ |
| BGE-M3 (self-hosted) | 1024 | Fast | Very Good | Free |
| all-MiniLM-L6 (self-hosted) | 384 | Very Fast | Good | Free |
For most production use cases, OpenAI text-embedding-3-small or BGE-M3 offers the best cost/quality tradeoff.
Vector Database Selection
- Pinecone — Fully managed, excellent for most use cases, generous free tier
- Weaviate — Self-hostable, strong metadata filtering, GraphQL interface
- pgvector — Run in PostgreSQL; great if you already use Postgres and volume is moderate
- Qdrant — Self-hostable, high performance, excellent filter support
- Chroma — Development and prototyping; not recommended for production
For enterprise production: Pinecone or Weaviate (self-hosted for data sovereignty).
Advanced Retrieval Techniques
HyDE (Hypothetical Document Embeddings)
Generate a hypothetical answer to the query, embed it, and use that embedding for retrieval. Improves recall for abstract or under-specified queries.
Re-ranking
Use a cross-encoder re-ranker (Cohere Rerank, BGE-reranker) to re-score top-k retrieved chunks. Dramatically improves precision.
Multi-query Retrieval
Generate multiple query variants from the original question, retrieve for each, and deduplicate. Increases recall for ambiguous queries.
Self-query
Let the LLM parse the user’s query and generate structured filters automatically. “What’s the return policy for electronics purchased in January 2025?” → filter: {category: “electronics”, date: {gte: “2025-01-01”, lte: “2025-01-31”}}.
Evaluation Framework
Never deploy a RAG system without evaluation. Key metrics:
Retrieval Metrics
- Context Precision: Are retrieved chunks relevant to the query?
- Context Recall: Are all relevant chunks being retrieved?
Generation Metrics
- Answer Faithfulness: Does the answer stay grounded in the context?
- Answer Relevancy: Does the answer actually address the question?
Tools: RAGAS, TruLens, LangSmith provide automated evaluation pipelines.
Production Checklist
- Chunking strategy validated against test queries
- Embedding model benchmarked on your domain
- Metadata schema designed for filtered retrieval
- Re-ranking layer implemented
- Hallucination detection enabled
- Citation/source attribution in responses
- Evaluation baseline established
- Monitoring for retrieval quality over time
- Update pipeline for knowledge base changes
- Cost monitoring and optimization
Implementing RAG for your enterprise? Our AI engineering team specializes in production RAG deployments. Schedule a technical consultation.