LangChain 0.2 + OpenAI GPT-4 Turbo: Building Production RAG Systems

RAG systems have revolutionized how enterprises deploy AI in 2025-26. Unlike fine-tuning, RAG lets you update knowledge without retraining.

Why RAG Beats Fine-Tuning

• **Cost**: Fine-tune GPT-4 = $3/1K tokens. RAG inference = $0.03/1K tokens (100x cheaper)
• **Latency**: Vector search <100ms vs fine-tuning redeployment (24+ hours)
• **Freshness**: Update documents instantly; no retraining required

LangChain 0.2 Setup: Production-Grade

Step 1: Document Ingestion Pipeline

Start with document loading and text splitting for optimal chunk sizes.