One of the most important tasks the DBA must periodically perform is apply patches. This ensures that the Oracle installation is kept updated and reduces the chances of encountering known bugs. Your company policy should define whether you should proactively patch your database or patch only when a symptom is noted. You should always thoroughly read and make sure you understand the instructions contained in the README file. There are two ways to patch the database; by means of interim patches, or by means of Patch Sets. The main difference between the first and the second option is that interim patches don't change the Oracle version and they are applied with the OPatch tool, while the Patch Sets are installed using Oracle Universal Installer and they change the fourth digit of the Oracle version number.

CPUs are quarterly patch bundles released by Oracle Support. It is important to keep the software protected up to the last available CPU. This ensures your database will be protected...