LongTableBench: Benchmarking Long-Context Table Reasoning across Real-World Formats and Domains

Liyao Li, Jiaming Tian, Hao Chen, Wentao Ye, Chao Ye, Haobo Wang, Ningtao Wang, Xing Fu, Gang Chen, Junbo Zhao


Abstract
We introduce **LongTableBench**, a benchmark for evaluating long-context reasoning over semi-structured tables across diverse formats, tasks, and domains. It comprises 5,950 QA instances spanning 7 table formats (e.g., Markdown, HTML, SQL), 18 domains, and input lengths up to 128K tokens, including multi-turn and multi-table settings. To ensure data quality, we combine symbolic supervision, cross-model validation, and human review. Evaluating 52 LLMs—including general-purpose, table-specific, and reasoning-enhanced models—reveals that only the strongest models maintain robust performance under increasing context lengths and format diversity. We further show that end-to-end models outperform compression-based approaches, especially on tasks requiring semantic integration. LongTableBench provides a rigorous, scalable testbed for advancing long-context tabular understanding and highlights key limitations in current LLMs’ structural and reasoning capabilities.
Anthology ID:
2025.findings-emnlp.638
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2025
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
11927–11965
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URL:
https://aclanthology.org/2025.findings-emnlp.638/
DOI:
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Cite (ACL):
Liyao Li, Jiaming Tian, Hao Chen, Wentao Ye, Chao Ye, Haobo Wang, Ningtao Wang, Xing Fu, Gang Chen, and Junbo Zhao. 2025. LongTableBench: Benchmarking Long-Context Table Reasoning across Real-World Formats and Domains. In Findings of the Association for Computational Linguistics: EMNLP 2025, pages 11927–11965, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
LongTableBench: Benchmarking Long-Context Table Reasoning across Real-World Formats and Domains (Li et al., Findings 2025)
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https://aclanthology.org/2025.findings-emnlp.638.pdf
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