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RAG vs Long-context window

Fetch-relevant-context vs stuff-everything-in-context.

RAG retrieves a small relevant subset. Long context (1M tokens) can fit entire documents. Different tradeoffs on cost, latency, and quality.

At a glance

RAGLong-context window
Cost per queryLowHigh (full context billed)
LatencyLowerHigher
QualityDepends on retrievalCan degrade mid-context
FreshnessEasy to refreshSame

When to pick RAG

Large corpora, recurring queries, cost sensitivity.

When to pick Long-context window

One-off analysis of a single long document.

My verdict

For production systems, RAG. Long-context is for specific use cases, not a general replacement.

Further reading