Bulk Writing to PI Points: Choosing the Most Efficient Method

When working with OSIsoft PI System, it's common to encounter scenarios where you need to write multiple values to a PI Point Data Reference (DR). Selecting the most efficient method for bulk data writes can save time and reduce system load—especially when working at scale.

The Two Common Methods

1. PIPoint.PIData.UpdateValues

   • This method allows you to send a collection of values to the PI Data Archive in a single call. It's built for efficiency and optimized for handling bulk inserts. Fewer round-trips to the server mean faster writes and less network overhead.

2. AFAttribute.SetValue (Multiple Calls)

   • Here, you use the AFSDK’s AFAttribute.SetValue method in a loop, writing one value at a time. Each call results in a separate roundtrip to the server, introducing latency and consuming more system resources when scaling up the number of values.

Which Method Should You Use?

For writing many values to a PI Point DR, PIPoint.PIData.UpdateValues is significantly more efficient than calling AFAttribute.SetValue multiple times. Here's why:

• Reduced Server Roundtrips: Instead of opening a new connection and transaction for each value, you batch the values into a single transaction.
• Optimized for Bulk Operations: The UpdateValues API is designed specifically for handling groups of values, minimizing overhead.

Practical Example

Suppose you have a list of new sensor readings to insert:

// Assume pipoint is an instance of PIPoint
List<AFValue> valuesToWrite = GetSensorReadings();
IList<AFValue> errors;

// Bulk write
pipoint.Data.UpdateValues(valuesToWrite, AFUpdateOption.Insert, AFBufferOption.BufferIfPossible, out errors);

Compare this to calling SetValue in a loop:

foreach (AFValue val in valuesToWrite)
{
    myAttribute.SetValue(val, AFUpdateOption.Insert);
}

The first approach is faster and puts less strain on your infrastructure.

Best Practices

• Use UpdateValues whenever inserting or updating multiple values to a PI Point.
• Reserve SetValue for occasional, single-value updates where simplicity or imperative logic is paramount.

Conclusion

If performance and efficiency matter (and they almost always do), opt for PIPoint.PIData.UpdateValues when inserting multiple values to a PI Point Data Reference. It’s a simple change that can lead to significant benefits for both developers and system administrators.