I have a production webserver with a MySQL database setup as Master. I have a dev server with MySQL setup as Slave, with the data successfully being replicated from the Master.
What happens when a developer commits a chance to the Slave db? Is that commit going to screw up the whole setup?
If this is not the ideal situation for a Production / Dev / Staging setup, what would the ideal setup be?
If you're committing to the same database that's being replicated then yes, it will most certainly screw things up.
You ought to have a completely different database that your developers can work against. If you want it to be refreshed periodically from production data, that would be fairly easy to set up and automate.