# V2 Multi-Stage Query Engine

## Overview

The new multi-stage query engine (a.k.a V2 query engine) is designed to support more complex SQL semantics such as `JOIN`, `OVER` window, `MATCH_RECOGNIZE` and eventually, make Pinot support closer to full ANSI SQL semantics. 

<figure><img src="/files/tEdVIXg8YoHz7sKY8Mn9" alt="Scatter-Gather Query Engine"><figcaption><p>Scatter-Gather Query Engine</p></figcaption></figure>

<figure><img src="/files/4V5EIsevVyAiXlBckmkx" alt="Pinot Multi-Stage Query Engine"><figcaption><p>Multi-Stage Query Engine</p></figcaption></figure>

It also resolves the bottleneck effect for the broker reduce stage where only a single machine is dedicated to perform heavy lifting such as high cardinality `GROUP BY` result merging; `ORDER BY` sorting, etc.

## How to use the V2 query engine

To enable the V2 engine,&#x20;

1. please make sure to either&#x20;
   * [Building Apache Pinot](https://github.com/apache/pinot#building-pinot) using the latest master commit.
   * Download the latest Apache Pinot docker image using the [official guide](https://docs.pinot.apache.org/basics/getting-started/running-pinot-in-docker).
2. Please add the following configurations to your cluster config:
   * ```
     "pinot.multistage.engine.enabled": "true",
     "pinot.server.instance.currentDataTableVersion": "4",
     "pinot.query.server.port": "8421",
     "pinot.query.runner.port": "8442"
     ```
3. Start the cluster normally, you should see the following window in the controller query page:

   <figure><img src="/files/HWPFZ5YCB0d7KJI95TuJ" alt=""><figcaption><p>Sample Query Screenshot</p></figcaption></figure>

## Design Details

The overall PEP design doc and discussion can be found in the following links

* [PEP discussion Github Issue](https://github.com/apache/pinot/issues/8260)  and
* [PEP design doc](https://docs.google.com/document/d/10-vL_bUrI-Pi2oYudWyUlQl9Kf0cLrW-Z8hGczkCPik/edit#)


---

# 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.pinot.apache.org/release-0.11.0/developers/advanced/v2-multi-stage-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.