Codeigniter for large projects!

Hi, I've been using CI for awhile for small projects. When I did my reading about usage of CI a few years ago, I read that it is good for small to medium applications. I've search over the internet about using CI for large projects, but nothing really serius appears. So, my question is: Is really good idea use CI for a large project? And when I say large project I mean a project that will handle a high amout of data and intense interaction with MySQL or PostgreSQL DBs..