- Surprising result
- Reframes the problem
Retrieval Augmented Generation Compositionality
RAG pipeline components do not reliably compound their isolated performance gains when combined, and the best-performing pipeline composition shifts as document corpus size expands.
The authors created LASAGNA, an open-source evaluation framework, to test 450 RAG configurations across eight benchmarks and corpus sizes from 5K to 200K documents. They found that combining individually strong techniques yielded significantly lower improvements than expected, optimizing for retrieval could degrade faithfulness, and winning architectures varied with corpus scale. Consequently, isolated component benchmarks are poor predictors of end-to-end system efficacy.
Client angle, caveats & evidence
Client angle Relevant if a client is stacking multiple RAG components under the assumption that benchmark gains will compound additively at enterprise scale.
Caveats The study tests corpora up to 200K documents, which may not capture dynamics in ultra-large enterprise repositories.
“three retrieval techniques predict a +47% combined improvement but deliver only +17% when used together.”