4 Replies Latest reply on Jan 12, 2018 6:56 AM by skwan

    Help with analysis performance issues!


      Hi All,


      I've been having some problems with analysis performance.


      The figure below shows the issue I'm having. The blue line is the result of an analysis that's based on the data shown in red. The analysis was back-filled until a bit over halfway across the graph and the rest is the result of letting it run by it's self. 

      The back-filled data is as expected, values written to the Pi Point every 5 minutes. However when letting the analysis run, it only returns values at much larger intervals and even then they seem to lag behind the red trend.



      This analysis template is only running on 2 elements. There are only 80 other analyses so far, most of which are fairly simple and run either hourly or daily.  I wouldn't expect to be running into performance issues with so few analyses, is there perhaps something I'm missing here?


      Any help would be much appreciated!




        • Re: Help with analysis performance issues!

          Hi Scott,

          I'd be surprised if it was a server performance issue. In our experience analyses whilst being memory hungry, are pretty efficient, we have tens of thousands of them running quite happily.

          Are you able to post the analysis setup and the target tag config (compression settings etc)? That might give us some clues.


          Is this running in Prod? Do you have a dev/test system to compare it with?



          • Re: Help with analysis performance issues!
            Dan Fishman

            It looks like a data compression issue because the back-filled data is uncompressed (all values written) since it is out of order and the real-time data is compressed.  Does it really lag, or is it the data density of real time is less dense than that of the back-filled data?  The data is relatively linear for many periods so I would expect no values during those times if you have compression on.



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            • Re: Help with analysis performance issues!

              Hi Scott,


              I agree with Dan Fishman here. I suspect that if you tracked the snapshot of the blue tag while the analysis is running that you may see it updating every 5 minutes (unless your the exception settings except it out). However, after the fact, only the events that meet the tag's compression settings are archived.


              Please let us know if taking a look at these settings helps!





                • Re: Help with analysis performance issues!


                  There are quite a few performance counters for PI Analysis Service.  You can take a look at those to see if you're lagging behind.  I suspect you're not.  Based on what I'm seeing on your screen shot, I would tend to agree with Dan that PI Analysis Service is calculating every 5 minutes, but the calculated outputs are being compressed out due to the compression deviation setting of your analysis output PI Points.


                  Steve Kwan

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