[otrs] Which DB should I use? Mysql, PostgreSQL or Oracle?

Hi! I'm in a project where we are going to install an OTRS to a huge university here in Rio de Janeiro (Brazil). They are expecting about 5,000 tickets per day. I don't if this is a lot of information for a MySql installation, so I have this question: Is a MySql installation a good choose for us? Or should I consider another DB for this project? Why some people prefer to choose PostgreSQL or Oracle sometimes? Thanks!! Ronaldo Richieri Brazil +55 15 8818-2009