# Sub-Question Query Engine

A query engine designed to solve problem of answering a complex query using multiple data sources. It first breaks down the complex query into sub questions for each relevant data source, then gather all the intermediate reponses and synthesizes a final response.

<figure><img src="/files/7ASrycAtL3X2u76sbKVI" alt=""><figcaption></figcaption></figure>

## Inputs

* Query Engine Tools
* Chat Model
* Embeddings
* [Response Synthesizer](/integrations/llamaindex/response-synthesizer.md)

## Parameters

| Name                    | Description                                                         |
| ----------------------- | ------------------------------------------------------------------- |
| Return Source Documents | To return citations/sources that were used to build up the response |

## Outputs

| Name                   | Description                   |
| ---------------------- | ----------------------------- |
| SubQuestionQueryEngine | Final node to return response |


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.flowiseai.com/integrations/llamaindex/engine/sub-question-query-engine.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.