AMP Engine Percentile Bug

[SamBealing]

We have recently upgraded to Alteryx Designer x64 Version: 2022.1.1.25127.

I have found an issue when calculating percentiles using the summarize tool on large data sets. 

In the attached workflow, I generate some long arithmetic sequences and then use the summarize tool to find the 50th percentile (median).

With the AMP engine turned on, a lot of these percentiles come out to the wrong values. What seems to be happening is that the correct percentile from one group is being outputted as the percentile for multiple groups. All these percentiles should be distinct and yet:

I turn the AMP engine off and the issue goes away.

Wonder if this is an issue any one else has had and if it can be fixed/there is a workaround.

[MarqueeCrew]

@SamBealing ,

 looks like a 🐛 to me too. 

@TonyaS @jarrod 

cheers,

mark

[TonyaS]

Thanks @SamBealing  for the workflow. That will help a lot. 

We'll take a look.  I do also want to mention that there are some patches available for 22.1 - there is 1 already out and another coming out any day. Might want to wait for patch 2. https://alteryx.flexnetoperations.com/flexnet/operationsportal/entitledDownloadFile.action?downloadP... 

[TonyaS]

I have created a defect for this, I'll let you know when I find out more. 

[SamBealing]

Thanks @TonyaS .

[Edotime]

I have downloaded the latest patch, turned off the AMP engine, and this issue is still persist.  Is there another work-around?  Do i have to revert to an older version (is this even possible)?

Thanks

[TonyaS]

So @Edotime are you saying this is not an AMP specific issue? 

@SamBealing can you confirm this? Did you only see the issue you posted about with AMP enabled? Or does it also happen without AMP?

[Edotime]

From what I can tell, this is not an AMP bug.  But just to verify, I want to confirm that I actually turned off the AMP correctly.  I turned off the AMP by removing the selection in the screenshot attached.

I ran some additional test and I am seeing some strange behavior:

--  I see this error in a large workflow

-- I break the data into smaller chunks in this same large workflow, and it works fine for some subsets, but not for all

--  I get the data from this large workflow going into the percentile calculation, save it in a yxdb file, and rerun the same percentile logic in another canvas and the percentiles look perfect

I completely confused...not sure what is going on.

 

[TonyaS]

That setting only turns off the User Setting to enable AMP when building new workflows. There is a workflow-level setting under the Workflow Configuration - Runtime tab. To turn AMP off for a workflow that was created/saved with AMP enabled, you need to uncheck the "Use AMP Engine" checkbox there. 
You can also try using AMP with "Engine Compatibility Mode" checked, that setting maintains the same sortation method as the original Engine uses. 

[TonyaS]

I just confirmed that this is fixed on the Release Candidate build for our upcoming 2022.3 Release. AMP now returns the same results as the original Engine. 

It does appear that the issue was AMP specific. 

You can also tell whether a workflow ran with AMP by viewing the Results: