Rethinking Schema Linking: A Context-Aware Bidirectional Retrieval Approach for Text-to-SQL

Md Mahadi Hasan Nahid, Davood Rafiei, Weiwei Zhang, Yong Zhang


Abstract
Schema linking—the process of aligning natural language questions with database schema elements—is a critical yet underexplored component of Text-to-SQL systems. While recent methods have focused primarily on improving SQL generation, they often neglect the retrieval of relevant schema elements, which can lead to hallucinations and execution failures. In this work, we propose a context-aware bidirectional schema retrieval framework that treats schema linking as a standalone problem. Our approach combines two complementary strategies: table-first retrieval followed by column selection, and column-first retrieval followed by table selection. It is further augmented with techniques such as question decomposition, keyword extraction, and keyphrase extraction. Through comprehensive evaluations on challenging benchmarks such as BIRD and Spider, we demonstrate that our method significantly improves schema recall while reducing false positives. Moreover, SQL generation using our retrieved schema consistently outperforms full-schema baselines and closely approaches oracle performance, all without requiring query refinement. Notably, our method narrows the performance gap between full and perfect schema settings by 50%. Our findings highlight schema linking as a powerful lever for enhancing Text-to-SQL accuracy and efficiency.
Anthology ID:
2026.findings-eacl.236
Volume:
Findings of the Association for Computational Linguistics: EACL 2026
Month:
March
Year:
2026
Address:
Rabat, Morocco
Editors:
Vera Demberg, Kentaro Inui, Lluís Marquez
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
4516–4546
Language:
URL:
https://preview.aclanthology.org/ingest-eacl/2026.findings-eacl.236/
DOI:
Bibkey:
Cite (ACL):
Md Mahadi Hasan Nahid, Davood Rafiei, Weiwei Zhang, and Yong Zhang. 2026. Rethinking Schema Linking: A Context-Aware Bidirectional Retrieval Approach for Text-to-SQL. In Findings of the Association for Computational Linguistics: EACL 2026, pages 4516–4546, Rabat, Morocco. Association for Computational Linguistics.
Cite (Informal):
Rethinking Schema Linking: A Context-Aware Bidirectional Retrieval Approach for Text-to-SQL (Nahid et al., Findings 2026)
Copy Citation:
PDF:
https://preview.aclanthology.org/ingest-eacl/2026.findings-eacl.236.pdf
Checklist:
 2026.findings-eacl.236.checklist.pdf