Support deletion/reset of snapshot values in the Buffering subsystem
The Analysis server uses the PI Buffer subsystem in order to apply Exception and Compression testing on the results of Analysis. However, when deleting data (either through Recalculation or deleting data via Powershell or PI SMT, or whatever) the PI Buffer subsystem on the Analysis server never resets the stored snapshot value/timestamp.
The consequence of this is that if the same Analysis is recalculated multiple times (for example after corrections, optimization, etc), compression is only ever applied the very first time an Analysis is recalculated. After that, compression is never applied up to the timestamp that the recalculation was run up to, as the PI Buffer subsystem never resets the actual current snapshot value/time.
In the referenced thread, the only workaround is to completely stop the PI Buffering Subsystem on the Analysis Server, delete the cache, release ownership of the PI Points on the Data Archive, restart the Buffering Subsystem, and then hope that everything works.
It would be way easier to be able to tell the Buffering Subsystem to get the current Snapshot from the Data Archive.
Reference in this thread on PI Square: