Friday, April 14, 2023

Purging PeopleTools Physical Cache Files after Database Restore or Database Flashback

I have written previously about how to clear the physical cache files on a PeopleTools process, but I have found myself explaining it a few times recently, so I am going to post about it again.

When you refresh the database of a PeopleSoft system, you need to clear the physical cache files of the PeopleTools processes.  The files are outside the database and they no longer reflect what is inside the database.  This includes all application servers and process schedulers and anywhere where Application Designer or a client process is used.

It is common to refresh a database when testing a PeopleSoft system.  For example, to copy production to a performance test environment.  It is also increasingly common to use Oracle database flashback during testing.  A guaranteed restore point is taken, a test is performed, and then the database is flashed back to that restore point.  Flashback returns the whole database not just to the same logical state, but also the same physical state.  Block for block, the entire database is physically the same as when the restore point was taken.  Thus a test is completely repeatable with the same initial conditions.  Although the database instance will have been restarted during the flashback so the content of the database memory will have been cleared.

It is also common, after the flashback to then make small changes or corrections, take a new restore point and repeat the test.  Some of those changes might include Application Designer projects that will then be loaded into the physical cache.  Flashing the database back won't change the physical cache files stored outside the database, so they need to be cleared too.  Otherwise, they may have higher version numbers than the objects in the database, and caching won't work correctly.  When you retest, your changes may not be loaded and executed by PeopleTools processes.

The officially approved method is to go around each server and use either the purge option in the psadmin utility or manually delete the files.  See:

However, since at least PeopleTools 5, it has been possible to invalidate all physical cache files on all servers by updating the LASTREFRESHDTTM on the single row in table PSSTATUS.  Any cached object older than the value of LASTREFRESHDTTM will be purged from the cache when the process that reference that cache is started. Therefore, if immediately after a restore or flashback that value is updated to the current system time, all caches will be purged as the processes are restarted.


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