Long Context vs RAG in 2026: When to Use Which?
Introduction
Every time a model ships with a larger context window, the debate resurfaces: "RAG is dead, just put everything in the context." In 2026, Gemini 3.1 Pro pushes up to 2 million tokens, Claude and GPT hold at 1M. The question is legitimate.
But in the field, it's not that simple. I've seen teams burn thousands of euros on API calls thinking they were "simplifying" their stack by dropping RAG. I've also seen teams build a full RAG pipeline to answer questions on 3 pages of documentation. In both cases, they were using the wrong tool for the problem.