5 Replies Latest reply on May 25, 2018 5:26 AM by jyi

    How future data works? How much historical data it use to determine the future data?

    Abu.Salam

      When we want to determine the future data for a PI point using PI Analyses - can anyone tell how much historical data it use to populate the future data?

       

      Lets say, I am trying to populate 1 day of future data for a Wellhead pressure.  How much time it will go back or how much historical data it will use to determine and predict this 1 day?  Does it go a month back, a year back?  What is the mechanism it uses?

       

        • Re: How future data works? How much historical data it use?
          Lal_Babu_Shaik

          Hi Abu Salam

           

          Choosing between historical or future PI points is a key decision that depends on whether the data that must be stored is real-time data i.e. collecting continuous measurements, or data that may not be close to current time or prediction.

           

          Future PI points can store data with both future and past time stamps, OSIsoft strongly recommends against mixing predicted and measured data in the same PI point. Use future PI points for forecast data and historical PI points for actual or measured data.

           

          By default, future PI points have their step attribute turned on (set to 1). This is because most future PI Points store discontinuous signals (for example, a series of discrete predictions) for which linear interpolation cannot be assumed. With the step attribute turned on, trends show a staircase pattern. Future PI points, by default, also have compression, excmin, excmax and excdev turned off (set to 0).

           

          By default, future PI points have their step attribute turned on (set to 1). This is because most future PI Points store discontinuous signals (for example, a series of discrete predictions) for which linear interpolation cannot be assumed. (Reference OSIsoft Live Library)

          • Re: How future data works? How much historical data it use?
            jyi

            Hi Abu Salam,

             

            I think that there's a small misunderstanding here. This misunderstanding is in fact, quite common about the future data.

            Just like the historical data, PI Data Archive does not generate a future data for you. We can have a data source for them just like the historical data.

            (PI Analysis Service can be one of the sources for your future data. Here you can decide which predictive model you want to use to predict your future data. It is up to you to decide how much historical data you will use)

             

            We do provide a singular, consistent and reliable data infrastructure for storing the time series data that are in the future. And of course, we also provide the PI client tools that support comparing the future data with the real-time data nicely.

            Please feel free to leave any questions or comments!

            1 of 1 people found this helpful
            • Re: How future data works? How much historical data it use?
              tramachandran

              With PI Data Archive 2015 you can capture and analyze data with future time stamps (beyond current time). You can populate Future PI points with data that is time-stamped prior to current time: PI Data Archive allows you to write future PI point values anywhere in the UTC time range (1970-2038).

               

              I recommend checking Future Data section in the server documentation for a good understanding of

                   Difference between historical and future data

                   Future time stamp format

                   Products supporting future data

                   Future PI points

                   Future archives

                   Analytics with future data

               

              Learning Channel Videos

              How is Future Data Stored in the PI System?  

              What is Future Data?

              1 of 1 people found this helpful
              • Re: How future data works? How much historical data it use?
                Abu.Salam

                Thank you everyone for your response.  However, my question might not be clear what I tried to mean.  I understand and know what 'Future Data' is and how it stores etc.  Let's take and example and let me try to make my question clear.

                 

                Let's say I am using Advance option in AF Analyses as below to generate future data for *+1d.  How much historical data it will go back to use as it's pattern to predict this data?  Will it use 1 month or 1 year of historical data to come up with this 1 day of future data?

                 

                Am I clear now?