We are setting up sonar with maven build using what is described here. However I am interested in finding out if it is possible to set up sonar without having a database. Is it possible for sonar to generate a PDF with all metrix in memory and save it to some directory for later use than saving in to database?
No. Practically everything in Sonar is stored in a database, so you must have one. PDF isn't any kind of reasonable way to store something for later use. If you're looking for reports in PDF format, there's a PDF plugin, but I've never used it.