There is nothing 'just' about moving a non-trivial database from one rdbms to another. First there is no doubt a huge amount of incompatibility between the dialect of SQL the two speak. Then there's all the platform specific features that the other database is either lacking or implement completely differently. On top of that, once you get everything up and running, you'll notice that the performance characteristics between the two are very different which means you're going to have to redo much of your optimization work to get back to even close to the level of performance you had before the switch.