I have developed a queueing library for Ruby that uses PostgreSQL as the backend. With the combination of row-level locking, PUB/SUB and PL/pgSQL, PostgreSQL was a perfect fit for this database backed queue. In the talk, I will highlight the motivations and pitfalls I discovered while building and maintaining Queue Classic. I will also discuss the environments in which the Queue Classic is running. Queue Classic supports a variety of components: runtime, database provisioning & financial services.