ORDER: Task-Conditioned Routing for Retrieval-Augmented Generation

Aurélien Pellet, Marie Puren, Julien Perez


Abstract
Retrieval-Augmented Generation (RAG) pipelines typically rely on a fixed indexing and retrieval configuration determined at preprocessing time. This one-size-fits-all design is ill-suited to domain-expert settings, where heterogeneous queries require different chunking granularities, metadata constraints, and source-selection strategies. As a result, configurations that are effective for one family of queries often perform poorly for others. In this paper, we introduce ORDER (Optimal Routing for Dynamic Evidence Retrieval), a query-conditioned RAG framework that jointly adapts indexing and retrieval to the incoming query. Our approach first discovers semantic clusters over a given set of questions associated to a corpus and learns, for each cluster, a chunking strategy together with a suited metadata filtering and reranking configuration. At inference time, queries are routed to the appropriate pre-built index through nearest-centroid assignment. To further improve retrieval, we propose a supervised query router (QRe) that predicts which collections are most likely to contain relevant evidence, coupled with a Uniform Multi-source Sampler (UMS) that allocates the retrieval budget evenly across the selected sources. We evaluate our framework on large-scale, heterogeneous historical archives and show that conditioning both indexing and retrieval on the query consistently outperforms both naive baselines and strong state-of-the-art RAG systems in complex expert-domain environments.
Anthology ID:
2026.findings-emnlp.2026
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
43092–43126
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2026/
DOI:
Bibkey:
Cite (ACL):
Aurélien Pellet, Marie Puren, and Julien Perez. 2026. ORDER: Task-Conditioned Routing for Retrieval-Augmented Generation. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 43092–43126, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ORDER: Task-Conditioned Routing for Retrieval-Augmented Generation (Pellet et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2026.pdf