Just use Postgres for everything
postgresql handles queues well.  the tricks are skip lock, hiding the db behind protocols/micro services and judicious use of unlogged tables.<p>here is a 2015 talk on critical messaging using pg.<p><a href="https://github.com/jmscott/talk/blob/master/ams-pgopen-20150917.pdf" rel="nofollow">https://github.com/jmscott/talk/blob/master/ams-pgopen-20150...</a>