Zijian Chen


2025

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QuackIR: Retrieval in DuckDB and Other Relational Database Management Systems
Yijun Ge | Zijian Chen | Jimmy Lin
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: Industry Track

Enterprises today are increasingly compelled to adopt dedicated vector databases for retrieval-augmented generation (RAG) in applications based on large language models (LLMs).As a potential alternative for these vector databases, we propose that organizations leverage existing relational databases for retrieval, which many have already deployed in their enterprise data lakes, thus minimizing additional complexity in their software stacks.To demonstrate the simplicity and feasibility of this approach, we present QuackIR, an information retrieval (IR) toolkit built on relational database management systems (RDBMSes), with integrations in DuckDB, SQLite, and PostgreSQL. Using QuackIR, we benchmark the sparse and dense retrieval capabilities of these popular RDBMSes and demonstrate that their effectiveness is comparable to baselines from established IR toolkits. Our results highlight the potential of relational databases as a simple option for RAG scenarios due to their established widespread usage and the easy integration of retrieval abilities. Our implementation is available at quackir.io.

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Zero-Shot ATC Coding with Large Language Models for Clinical Assessments
Zijian Chen | John-Michael Gamble | Micaela Jantzi | John P. Hirdes | Jimmy Lin
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 3: Industry Track)

Manual assignment of Anatomical Therapeutic Chemical (ATC) codes to prescription records is a significant bottleneck in healthcare research and operations at Ontario Health and InterRAI Canada, requiring extensive expert time and effort. To automate this process while maintaining data privacy, we develop a practical approach using locally deployable large language models (LLMs). Inspired by recent advances in automatic International Classification of Diseases (ICD) coding, our method frames ATC coding as a hierarchical information extraction task, guiding LLMs through the ATC ontology level by level. We evaluate our approach using GPT-4o as an accuracy ceiling and focus development on open-source Llama models suitable for privacy-sensitive deployment. Testing across Health Canada drug product data, the RABBITS benchmark, and real clinical notes from Ontario Health, our method achieves 78% exact match accuracy with GPT-4o and 60% with Llama 3.1 70B. We investigate knowledge grounding through drug definitions, finding modest improvements in accuracy. Further, we show that fine-tuned Llama 3.1 8B matches zero-shot Llama 3.1 70B accuracy, suggesting that effective ATC coding is feasible with smaller models. Our results demonstrate the feasibility of automatic ATC coding in privacy-sensitive healthcare environments, providing a foundation for future deployments.