Title: Structured Retrieval-Augmented Generation for Multi-Doc Multi-Entity Question Answering
Primary area: generative models
Keywords: Structured Retrieval-Augmented Generation, Multi-document Multi-entity Question Answering

Abstract: Multi-document Multi-entity Question Answering (MDMEQA) fundamentally requires models to track and connect the implicit logic between multiple entities across documents, a task that reveals critical limitations of Large Language Models (LLMs) and Retrieval-Augmented Generation (RAG) frameworks: they struggle to construct effective cross-document evidence chains and deduce entity relationships when faced with fragmented information. Although RAG improves answering capabilities through context injection, its coarse-grained retrieval strategy that relies on vector similarity often leads to the omission of critical facts. Meanwhile, graph-based RAG fails to efficiently integrate scattered complex relationship networks in multi-document scenarios, resulting in low efficiency in retrieving and reasoning MDMEQA. We propose Structured Retrieval-Augmented Generation (SRAG): a two-stage framework that first transforms unstructured text into semantically coherent relational tables via a SQL-driven Extraction-Retrieval module, then guides LLMs toward schema-aware relational reasoning over structured representations. This architectural breakthrough offers three key advantages: (1) SQL-powered indexing enables precise fact localization; (2) relational tables naturally support multi-hop entity join operations; (3) the structuring process mitigates the attention diffusion effect of LLMs. To verify the effectiveness of our proposed method, we evaluate SRAG on two multi-document QA benchmarks, MEBench and Loong. The results show that SRAG significantly outperforms the current state-of-the-art long-context LLMs and RAG systems, achieving 27.2% and 27% improvements in accuracy respectively. These results highlight the importance of structured data representation in enhancing complex reasoning and answer precision in multi-document multi-entity  question answering. The source code and data have been made available at https://anonymous.4open.science/r/SRAG-07A7.