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249 - Oracle PSU and CPU

1. PSU’s(Patch set updates) are patch sets but with some major differences with respect to regular patch sets.

PSUs are referenced by their 5th place in the Oracle version numbers which makes it easier to track ( (e.g. and will not change
the version of oracle binaries (like sqlplus, exp/imp etc.) As of now (10.2, 11,2) , the best way to  determine the PSU version installed  is
to use opatch utility using the command below.

# cd $ORACLE_HOME/OPatch

# opatch lsinv -bugs_fixed | grep -i  PSU

Regular patch sets on other hand include major bug fixes and most of the time requires re-certification.
The importance of PSU is diminished once a regular patch set is released for a given version as they tend to be more security related fixes
as CPU is part of PSU

2. CPU's (Critical Patch Updates) are collections of security fixes for Oracle products. They are available to customers with valid support contracts.

PSUs  contain CPU’s and are released every quarter (like CPU’s) ; In other words  Critical Patch Update (CPU) is a subset of the Patch Set Update (PSU).
CPU’s are built on the base Patch Set version (e.g. whereas PSU are built on the base of the previous PSU (e.g.

A PSU can always be applied over any CPU where as applying a CPU over a PSU will roll back the PSU (at least for now).
Therefore it is easy to go from CPUs to PSUs and hard to go back to CPUs  from PSUs.



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Story | by Dr. Radut