> ## Documentation Index
> Fetch the complete documentation index at: https://wiki.platelunchcollective.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Sub-query

> A sub-query is an individual retrieval query generated by a model during fan-out, targeting a specific component of the parent query.

*Core concept* · *AI Search Infrastructure*

## Definition

A sub-query is an individual retrieval query generated by a model during fan-out. Each sub-query targets a specific component of the parent query. The unit of retrieval is the sub-query — not the parent query, not the page, but the passage that best answers this specific sub-question.

## Why It Matters for AI Search

Sub-queries are the actual retrieval targets. A user asks one question; the model generates several sub-queries and retrieves content against each. The content that gets cited is the content that answers one sub-query cleanly and completely — not the content that addresses the parent query broadly. Content strategy built around the parent query is targeting the wrong unit.

## Related Terms

<CardGroup cols={2}>
  <Card title="Query fan-out" href="/ai-search-glossary/query-fan-out" />

  <Card title="Query decomposition" href="/ai-search-glossary/query-decomposition" />

  <Card title="Parent query" href="/ai-search-glossary/parent-query" />

  <Card title="First-pass retrieval" href="/ai-search-glossary/first-pass-retrieval" />

  <Card title="Passage-level retrieval" href="/ai-search-glossary/passage-level-retrieval" />
</CardGroup>

## Relevant Plate Lunch Collective Services

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