You begin a business on the web,  nobody knows in future what is your data growth rate, so think that your idea on the web is successful and you want to expand it but limitation on your database will end  your growth and then you are at the end of road. mysql is not for enterprise and critical systems.

if you think that mysql is free so, oracle released express edtion that is free of charge  and if your business has expanded you can go to other oracle edition and buy it if your business is successful so you have enough money to pay for standard or enterprise edtion,  you must think to unlimited growth, data is mony and more data needs better repository and manager.

If your data is your money no doubt to deliver it to a bank that is more secure and with guard and other tools that save it 100%. oracle can do it for you.