Hello ,

I stumbled upon a problem related to the number of access to the pi server using PI SDK (to optimize reports performance) and I've been trying this for a number of days with no success. What I'm trying to do is something like this (C#):

DataTable GetTagsInterpulatedValues(List<string> tagsToFetchData, List<Period> periods, string filterExp)

What I'm trying to do is with each tag from "tagsToFetchData" retrieve for example 3 periods (dateStart and dateEnd) and with a PI Equation filter Round, of course this isn't very hard to do if i do a foreach for each tag and use another foreach for the periods and apply the filter to the tags PI Data but this makes multiple accesses to the PI server.. what i wanted to do is make all this 1 request.. is there any way to do this? Notice that the filter must have the tagname to make the round filter.. is there any more general way to apply to all tags?

Thanks in advance,
Phil

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Thanks for the fast response , I'll post the entire method i got so far and an example how i would use it.

Example Code:

List<string> tagsToFetchData = new List<string>();
tagsToFetchData.Add("SUBSTN.ANGLE1");
tagsToFetchData.Add("SUBSTN.ANGLE2");

List<Period> periods = new List<Period>();
periods.Add(new Period(new DateTime(2010, 1, 1), new DateTime(2010, 1, 2))); //Analyse Data from 1 january 2010 to 2 january 2010
periods.Add(new Period(new DateTime(2010, 1, 5), new DateTime(2010, 1, 6))); //Also Analyse from 5 january 2010 to 6 january 2010

//the following is wrong but you'll understand my problem here..I'm trying to round the values but also i want the values that aren't questionable also for all tags
string filterExp = "Round([ALL_TAGS], 22.5) AND IsSet([ALL_TAGS], \"q\") = 0"

public DataTable GetTagsInterpulatedValues(List<string> tagsToFetchData, List<Period> periods, string filterExp)
{
DataTable dt = new DataTable();
DataColumn timestamp = new DataColumn("timestamp", Type.GetType("System.String"));
dt.Columns.Add(timestamp);

PointList points = new PointList();

foreach (string tag in tagsToFetchData) {
PIPoint point = piServer.PIPoints[tag];
points.Add(point);

DataColumn dc = new DataColumn(tag, Type.GetType("System.String"));
dt.Columns.Add(dc);
}

ListData points_data = points.Data;
NamedValues trash;
foreach(Period p in periods) {
PointValueLists period_vals = points_data.InterpolatedValues(p.iniPeriod, p.endPeriod, 0, filterExp, FilteredViewConstants.fvRemoveFiltered, out trash, null);
foreach (PointValueList lst in period_vals)
{
PIValues pointValues = lst.PIValues;
}
}
return dt;
}

I know It's rather complicated, if its not possible could you suggest anything i could optimize here?



I find this interesting, is there any documentation i could see or an example how to achieve this?

Again thanks for your help

**EDIT** i forgot to assign the results to the DataTable but you get the main idea of what I'm trying to do

We are actually converting an already made PI OLEDB query to this method here (we are talking of millions of data to be processed here that was the reason of changing ).

Maybe I'll end up to separate them for each different filter if its not possible to combine filters in only 1 expression.

Thanks again!
Phil

**EDIT** I've tried using the methods from ListData using PointsList and it seems they aren't implemented (NotImplementedException): Summary, InterpolatedValues.. the only one that you mentioned works but that method only retrieves one element (ArcValue). Seems like they are still working on this class leaving me to the threaded execution you mentioned.

Thanks for the code, I'm going to analyse it now