Retrieval Augmented Generation or Long-Context LLMs? A Comprehensive Study and Hybrid Approach

Zhuowan Li, Cheng Li, Mingyang Zhang, Qiaozhu Mei, Michael Bendersky


Abstract
Retrieval Augmented Generation (RAG) has been a powerful tool for Large Language Models (LLMs) to efficiently process overly lengthy contexts. However, recent LLMs like Gemini-1.5 and GPT-4 show exceptional capabilities to understand long contexts directly. We conduct a comprehensive comparison between RAG and long-context (LC) LLMs, aiming to leverage the strengths of both. We benchmark RAG and LC across various public datasets using three latest LLMs. Results reveal that when resourced sufficiently, LC consistently outperforms RAG in terms of average performance. However, RAG’s significantly lower cost remains a distinct advantage. Based on this observation, we propose Self-Route, a simple yet effective method that routes queries to RAG or LC based on model self-reflection. Self-Route significantly reduces the computation cost while maintaining a comparable performance to LC. Our findings provide a guideline for long-context applications of LLMs using RAG and LC.
Anthology ID:
2024.emnlp-industry.66
Volume:
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
November
Year:
2024
Address:
Miami, Florida, US
Editors:
Franck Dernoncourt, Daniel Preoţiuc-Pietro, Anastasia Shimorina
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
881–893
Language:
URL:
https://aclanthology.org/2024.emnlp-industry.66
DOI:
Bibkey:
Cite (ACL):
Zhuowan Li, Cheng Li, Mingyang Zhang, Qiaozhu Mei, and Michael Bendersky. 2024. Retrieval Augmented Generation or Long-Context LLMs? A Comprehensive Study and Hybrid Approach. In Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 881–893, Miami, Florida, US. Association for Computational Linguistics.
Cite (Informal):
Retrieval Augmented Generation or Long-Context LLMs? A Comprehensive Study and Hybrid Approach (Li et al., EMNLP 2024)
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PDF:
https://aclanthology.org/2024.emnlp-industry.66.pdf
Poster:
 2024.emnlp-industry.66.poster.pdf
Presentation:
 2024.emnlp-industry.66.presentation.pdf