I have never been on a receiving end of an Oracle audit but customers I’ve talked to who have been unfortunate enough to participate in one likened the experience to having a very invasive medical procedure. This experience seems to be rooted in two issues: one, Oracle licensing is notoriously convoluted. There are actually consultants who make a living helping customers navigate the Oracle license maze. Another reason is that most Oracle software does not do much to prevent unlicensed use of software often leading to unsuspecting IT professionals getting too addicted to the features hey may not have the right to use.
MySQL licensing is the exact opposite. After all, when have you seen an open source company send in auditors to make sure you are compliant with the license. According to an article on SearchOracle.com, SUN customers have much to fear. According to this article, Oracle has used its prior acquisitions as an opportunity to review customer contracts. These reviews can quickly escalate in to a full blown audit and not just of the software licenses but also of maintenance contracts. If this is indeed true and Oracle repeats this behaviour of prior acquisitions some MySQL customers may find themselves living through a completely new experience. Ouch, doctor, that hurts!