The new patch on the block is causing problems. The release of the first Patch Set Update (PSU) has brought a whole new level of complexity to managing Oracle database patches. The most significant change comes from the fact that each PSU contains a large number of bug fixes and therefore an increased chance for patch conflicts with existing installed patches. Managing divergent sets of patches on many systems is getting more difficult. The likelihood that a patch you are installing will conflict with a patch already applied is increasing. To prevent the maintenance nightmare that is becoming more painful by the day, it's critical that a standard set of patches be deployed except in the case of special requirements, hopefully limited to a small set of environments which can get special attention.

Once a conflict arises, the remedy is a prerequisite/overlay patch – something that either exists already or must be created by Oracle support via a service request. Ensuring that these overlay patches are installed on many systems incrementally increases the challenge associated with patching going forward.

Why has the PSU been created? Well, going back a bit to the CPU – this was a bundle of patches released quarterly to patch security issues. It turned out to be a popular idea so the next logical progression was to mix together the security patches with other fixes that are both determined to be useful for a wide population and unlikely to cause instability (those will still be left for inclusion in later releases). The concept is that these PSUs will be released regularly with the CPUs and be an option for shops willing to accept a bit more testing and patch conflicts for the benefit of non-security updates on a more regular basis.

The question as to whether or not the CPU will be phased out in favor of the increased functionality of the PSU remains an open question. No official guidance has been given on this subject although the complexity of switching from using PSUs to CPUs on an Oracle Home is noted to be extremely challenging in the documentation. Be deliberate and consistent when deciding whether to take the PSU train or the CPU train – they go in different directions.