What's the best way to copy historical data from one PIPoint to another (on the same archive)?

@gmalek I personally would use a PowerShell script to accomplish this. Here it is:

<#
    This script gets the timestamps and values from a source tag and writes them to a destination tag. Useful in cases where a new tag with no
    history is created to replace a pi tag that does have history for the same measurement.  
#>

#~ CONFIGURATION ITEMS:
    #~ For Use With Multiple Years of Data:
    # $startArray = @("1-Jan-2023 00:00:00","1-Jan-2022 00:00:00","1-Jan-2021 00:00:00","1-Jan-2020 00:00:00","1-Jan-2019 00:00:00","1-Jan-2018 00:00:00")    
    # $endArray = @("1-Jan-24 00:00:00","1-Jan-2023 00:00:00","1-Jan-2022 00:00:00","1-Jan-2021 00:00:00","1-Jan-2020 00:00:00","1-Jan-2019 00:00:00")

    #~ For Use with Less than a Year's worth of Data:
    $startTime = "2-Apr-2024 00:00:00"
    $endTime = "10-Oct-2024 12:00:00"
    $piServerName = "YOUR_PI_SERVER_NAME_HERE"
    $sourcePIPoint = "YOUR_SOURCE_PI_TAG_NAME_HERE"
    $destinationPIPoint = "YOUR_DESTINATION_PI_TAG_NAME_HERE"

#~ CONNECT TO THE TARGET PI SERVER:
    $piConn = Connect-PIDataArchive -PIDataArchiveMachineName $piServerName

#~ FOR LOOP THROUGH ANNUAL TIME RANGES:
For ($i=0; $i -le $endArray.Count; $i++)  
{ 
    #~ GET COMPRESSED DATA:
       # Multiple Years: 
       # $results = Get-PIValue -PIPoint (Get-PIPoint -Name $sourcePIPoint -Connection $piConn) -StartTime $startArray[$i] -EndTime $endArray[$i]
       
       # Less Than A Year:
       $results = Get-PIValue -PIPoint (Get-PIPoint -Name $sourcePIPoint -Connection $piConn) -StartTime $startTime -EndTime $endTime
       ForEach ($result in $results)
       {
            #~ GET SOURCE TAG TIMESTAMP AND VALUE:
            $piTime = $result.TimeStamp.ToUniversalTime()
            $piTime.ToString("MM/dd/yyyy HH:mm:ss")
            $comma = ","
            $resultValue = $result.Value
            #~Write-Host $piTime$comma$resultValue

            #~ WRITE TIMESTAMP AND VALUE TO DESTINATION TAG:
            Add-PIValue -PointName $destinationPIPoint -Time $piTime -Value $resultValue -WriteMode Replace -Connection $piConn

            #~ Remove-PIValue -PointName $destinationPIPoint -Time $piTime -Value $resultValue -Connection $piConn        
       }
       Write-Host "End of Loop:" $i
       Sleep 5
       $result = ""
       $results = ""
}
   $results = ""
   $nowTime = Get-Date -DisplayHint Time
   Write-Host "Backfilling Complete For: " $destinationPIPoint " On " $piServerName " at " $nowTime
#~ DISCONNECT FROM PI SERVER:
    Disconnect-PIDataArchive -Connection $piConn

While JamesDevine​ has provided a custom code solution, I have an important question: is this to be a one-time copy, or once-a-day, or continually?

I am sure you are well versed in (A) the MaxArcCollect limit, (B) know something about the data rate of the tag(s) in question, and (C) know how wide of a time range you are interested in. For a big copy, A, B, and C all are factors on what you can do.

If it is a one-time copy and there are less than 1.5 million values, you can use SMT's Archive Editor to copy values from the source tag and paste into the target tag. For a small amount of tags, this is easy enough but for a huge amount of tags there can be a lot of inconvenient scrolling as well as very long wait times. But SMT is a build-in tool to help you achieve your goal.

If you wanted continual (event-triggered) or periodic updates, you can do this with an Asset Analysis. It would be a very simple Expression, and Analytics is considered a build-in tool. There is a limitation on how far back in history you can go, so you may need to catch-up on history to present before using Analytics to perform perpetual updates.

Rick_Davin_3.0​ The copy paste method is fairly easy one, however pasting didn't work in archive editor window (may be missed something).

gmalek​ there is another option, using datalink, export the compressed values of original tag into CSV file and back fill to new tag using PI piconfig script.