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Cache on PI Data Archive Servers

Question asked by darren9 on Feb 4, 2016
Latest reply on Feb 26, 2016 by pthivierge

Hello, I am working on a project to validate data we have recently loaded into the PI server and have a couple very specific questions on the behavior of the caching system on the PI server itself. I am using the AFSDK method PIPoint.RecordedValues() to retrieve Tag values from the Pi server to compare those values to the values of the data we imported for each and every tag:values. We have imported a massive amount of data. Nine years worth of about 500k tags per day. I have noticed that on the first call to the PIPoint.RecordedValues for a specific tag can take upto 3500ms to respond. The second call to this point is usually on the order of 3ms to 6ms as the first call prompted the PI server to move this tag to the servers cache thus increasing the second call for the same data. This is as expected. However, as we have so many tag:values we are validating I am curious on some of the performance metrics of the PI servers caching system itself. My questions are: 1.      How long does a cache entry stay in the cache? 2.      How many tags can the cache hold at any single moment? 3.      When does the cache reset/purge? 4.      Can we configure the cache on these parameters? 5.    When I request a PIPoint.RecordedValues(), what is actually moved to the cache? The Tag and all its points, just the tag, just the points in the date range requested, etc. Thanks for your help.

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