---
title: "History"
description: "Why Queen was written: head-of-line blocking in Smartchat, a workaround around Kafka, and the road from a C++ prototype to the Rust broker."
---

> Queen MQ documentation, for AI agents
> Complete self-contained summary of Queen MQ: https://queenmq.com/llms-brief.txt
> Fetch that first when the question is about the product rather than about this page.
> Index of all pages: https://queenmq.com/llms.txt

# History

Queen was born in October 2025, to solve head-of-line blocking in Smartchat. That product used
Kafka as the backbone between its microservices, and kept hitting the same wall: the queues whose
processing time is long and uneven, translations and agent replies, block everything queued
behind them. The first fix was a workaround. Consume from Kafka, write the task to PostgreSQL,
run a loop that does the work, publish back to Kafka.

That is where the idea came from: generalise the workaround into a small C++ broker with
PostgreSQL procedures of its own. It worked, it was traceable, and it removed the problem, so the
next step was to give it Kafka's semantics as well: consumer groups and replay.

By November 2025 the first prototype had replaced Kafka across Smartchat. From there the work was
speed and scale, from the 30,000 messages a second of the early versions to the million of the
current one, which arrived with a new Rust broker and a new PostgreSQL schema.

## Where it runs today

Queen is the engine of at least three products at Smartness, including both of the ones that have
to be real time. Between them they run about **60 queues, 100,000 partitions and 60 consumer
groups**, and that load sits at around **20% of a two-core PostgreSQL on GCP**: the cardinality
that this design makes cheap is exactly the cardinality that makes other brokers expensive.

The broker runs highly available, three replicas. It holds no coordination state, so the replicas
need nothing from one another and a rolling restart is a rolling restart, not a rebalance.

Queen today is complete, observable, fast, and simple to run and to keep running.

Source: https://queenmq.com/start/history/index.mdx