One reason: Most RDBMS&#x27;s aren&#x27;t designed for &quot;waiting for newly queued items&quot;. You literally have to have each worker poll at some time interval for new items: `SELECT * FROM jobs WHERE status = &#x27;new&#x27;`, transactionally claim the job, and if a worker dies, un-claim it. It&#x27;s not that it&#x27;s not possible to use an RDBMS and work around these problems, but generally, it won&#x27;t lead to the most scalable and robust solution for the problem. Message brokers &#x2F; AMQP are better designed for this problem set. If you have a small site, with a low volume queue, your RDBMS might be just fine though.