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Automatic recalculation is deleting data without recalculating the data.

Question asked by Cheerion Champion on May 29, 2019
Latest reply on May 30, 2019 by sraposo

I come across an inexplicable fact with automatic recalculation in PI Analytics that I would like to discuss with you in order to find a cause and hopefully a solution.


This is the build up of my structure:

  • Parent node
    • Child node 1
    • Child node 2
    • Child node 3


Represented like this in PI System explorer:



On all the child nodes, we have an attribute that is connected to a PI point representing the online power measurement of our gas turbines (child node 1 & 2) and steam turbine (childnode 3).


On the parent node, an attribute has an analysis as data source. This analysis is build up as roll up. The analysis is rolling up the online power measurement. Interesting to know, the online power measurement of child node 3 has (sometimes) late arriving data. Therefor I selected automatic recalculation once the late arriving data is loaded into the PI point, our roll up on the parent node will be triggered.


Next, I have an attribute that is translating the online power measurement (the roll up one) into a daily total.So once a day shortly after midnight a TagTot function triggered by the scheduled task. This analysis is also set as automatic recalculation as it should be trigerred once the roll up function is triggered by the late arriving data.


And now the inexplicable fact:


If I check the daily PI point on f.e. January 2nd, 2019, I will see a value on January 1st, 2019.

When I check the daily PI point on January 3rd, we will see values on January 1st and 2nd.

Expected behaviour so far...

Next I check the daily PI point on January 4th, we will see a value on January 1st but the daily value on January 2nd is no longer there. It seems to be deleted by the automatic recalculation but it is not recalculated. January 3rd is there.


It sometimes happens that January 2nd gets recalculated a couple of days later.


When automatic recalculation is deactivated, the calculation performs the daily calculations day by day without missing or erasing one. I switched automatic recalculation on and off several times the past couple of weeks. And values were deleted (and not recalculated) always when automatic recalculation is enabled and clearly not when it was deactived.


Did anybody encounter this issue when automatic recalculation is enabled?