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Main Authors: Chen, Jinwen, Zhang, Hainan, Pang, Liang, Tong, Yongxin, Zhou, Haibo, Zhan, Yuan, Lin, Wei, Zheng, Zhiming
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.01088
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author Chen, Jinwen
Zhang, Hainan
Pang, Liang
Tong, Yongxin
Zhou, Haibo
Zhan, Yuan
Lin, Wei
Zheng, Zhiming
author_facet Chen, Jinwen
Zhang, Hainan
Pang, Liang
Tong, Yongxin
Zhou, Haibo
Zhan, Yuan
Lin, Wei
Zheng, Zhiming
contents The current RAG system requires uploading plaintext documents to the cloud, risking private data leakage. Parametric RAG (PRAG) encodes documents as LoRA parameters within LLMs, offering a possible way to reduce exposure of raw content. However, it still faces two issues: (1) PRAG demands synthesizing QA pairs and fine-tuning LLM for each individual document to create its corresponding LoRA, leading to unacceptable inference latency. (2) The performance of PRAG relies solely on synthetic QA data while lacking internal alignment with standard RAG, resulting in poor generalization on out-of-distribution(OOD) inputs. Therefore, achieving high-efficiency parameterization while maintaining RAG-level performance remains a critical challenge for privacy-preserving reasoning. In this paper, we propose DistilledPRAG, a generalizable knowledge-distilled parametric RAG model aligned with standard RAG in document structure and parameter activation. We first synthesize QA pairs from single and multi-documents to enhance cross-document reasoning. Then, we mask the plaintext documents with a special token and translate them to LoRA via a parameter generator, maintaining the standard RAG document structure. Finally, guided by synthetic QA data, we train the parameter generator to match standard RAG's hidden states and output logits, enabling RAG-style reasoning without original documents. Experiments on four QA datasets show that DistilledPRAG outperforms baselines in accuracy and generalizes well on OOD data.
format Preprint
id arxiv_https___arxiv_org_abs_2509_01088
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Privacy-Preserving Reasoning with Knowledge-Distilled Parametric Retrieval Augmented Generation
Chen, Jinwen
Zhang, Hainan
Pang, Liang
Tong, Yongxin
Zhou, Haibo
Zhan, Yuan
Lin, Wei
Zheng, Zhiming
Computation and Language
The current RAG system requires uploading plaintext documents to the cloud, risking private data leakage. Parametric RAG (PRAG) encodes documents as LoRA parameters within LLMs, offering a possible way to reduce exposure of raw content. However, it still faces two issues: (1) PRAG demands synthesizing QA pairs and fine-tuning LLM for each individual document to create its corresponding LoRA, leading to unacceptable inference latency. (2) The performance of PRAG relies solely on synthetic QA data while lacking internal alignment with standard RAG, resulting in poor generalization on out-of-distribution(OOD) inputs. Therefore, achieving high-efficiency parameterization while maintaining RAG-level performance remains a critical challenge for privacy-preserving reasoning. In this paper, we propose DistilledPRAG, a generalizable knowledge-distilled parametric RAG model aligned with standard RAG in document structure and parameter activation. We first synthesize QA pairs from single and multi-documents to enhance cross-document reasoning. Then, we mask the plaintext documents with a special token and translate them to LoRA via a parameter generator, maintaining the standard RAG document structure. Finally, guided by synthetic QA data, we train the parameter generator to match standard RAG's hidden states and output logits, enabling RAG-style reasoning without original documents. Experiments on four QA datasets show that DistilledPRAG outperforms baselines in accuracy and generalizes well on OOD data.
title Privacy-Preserving Reasoning with Knowledge-Distilled Parametric Retrieval Augmented Generation
topic Computation and Language
url https://arxiv.org/abs/2509.01088