ModelRefs / Query Decomposition — AI Glossary

Query Decomposition — AI Glossary

Breaking a complex multi-hop query into simpler sub-queries, executing each against the retrieval index, and merging results.

Overview

Query decomposition (DECOMP, IRCoT, LlamaIndex SubQuestionQueryEngine) identifies atomic sub-questions from complex queries (e.g., 'Who founded the company that acquired X?'), retrieves evidence per sub-question, and synthesizes a final answer. Significantly improves multi-hop QA benchmarks (HotpotQA, MuSiQue).

Reference details

Topicrag
Last reviewed2026-06-24

Commonly confused with

For questions that need more than one retrieval to answer — comparisons, or anything requiring a fact found in one place and a fact found in another. Rewriting and expansion both still issue a search for a single question; decomposition accepts that no single search can succeed, so it is the right tool exactly when the query is multi-hop and the wrong one when it is merely vague.

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Frequently asked questions

What is Query Decomposition?

Breaking a complex multi-hop query into simpler sub-queries, executing each against the retrieval index, and merging results.

What concepts are related to Query Decomposition?

Closely related concepts include query rewriting, multi document qa, advanced rag.