I implemented a message queue in MySQL too and it worked pretty well. Incoming messages would be written to the table and the workers would poll the database e

I implemented a message queue in MySQL too and it worked pretty well. Incoming messages would be written to the table and the workers would poll the database each cron period and process whatever rows were in the queue. To avoid race conditions, the workers would lock the records they were working on and then delete them as soon as the work was complete. It was simple but it worked just fine for my purposes