Overview
Weighing an expensive, powerful relational index against a lightweight, cheap semantic match — and choosing correctly for your query mix.
Why it matters
GraphRAG is not a strict upgrade over naïve RAG — it's a different tool with real operational cost: an extraction pipeline, a graph database, community detection, and a more complex query planner. Reaching for it by default is a common and expensive mistake.
Naïve RAG wins when queries are direct and single-hop: 'What was the company's Q3 revenue?' has one answer sitting in one chunk. Vector search finds it in milliseconds with no graph infrastructure at all — building a graph pipeline here adds latency, cost, and failure surface for zero benefit.
GraphRAG earns its cost when queries require cross-document synthesis or multi-hop reasoning: 'Which of our suppliers were also named in a competitor's litigation over the past three years?' has no single-chunk answer — it requires composing facts across entities and relationships that naïve RAG structurally cannot assemble, no matter how large k gets.
The decision isn't about corpus size or entity count in isolation — it's about what fraction of real queries are single-hop lookups versus multi-hop relational questions. A 100-million-document corpus where every question is still 'what does clause X say' is still better served by naïve RAG; a modest 10,000-document corpus where users constantly ask 'who's connected to whom' justifies GraphRAG immediately.
