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Question

ChangeDetector features output through Updated port but with 'INSERT' fme_db_operation


dms2
Contributor
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Working with FME Form 2023.2.2.

Comparing features using a ChangeDetector transformer I see a weird behaviour. It does not always happen though but can’t see a pattern.

I see features correctly output though Updated and Inserted ports but all of them have value ‘INSERT’ in fme_db_operation attribute. Has anyone experienced something like this?

 

4 replies

crutledge
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  • June 18, 2025

Hi ​@dms2 

I think you get both. The difference is outlined in the documentation.

This port is only relevant when Update Detection Key Attributes are specified in the “Transformer” section of the parameters.

When Changed Output > Mode is Insert & Update, a Revised feature is output via the Updated port when it has been prejoined on a unique key, but it differs from the Original feature that shares the same unique key.

Hope that helps!

 


dms2
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  • June 18, 2025

@crutledge I did set the Update Detection Key Attributes because I want to detect changes on features based on a unique key. That’s why I don’t understand the behaviour I mentioned, which is quite random I think.


crutledge
Influencer
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  • June 18, 2025

Hi ​@dms2 I follow you now. From what you describe I would expect Update not Insert too. I see the one changedetector is _19 and the other is _4. Have you tried deleting that _19 and using a fresh change detector? If you delete that _19 change detector does the next change detector _4 output Insert instead of Update? The IDs are the same fields in both? This is a new workbench or customizing an existing one? The transformers are the same version?

Hopefully that helps but might share the workbench with support.


dms2
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  • June 25, 2025

Hi, 

I added the that _4 ChangeDetector to test whether my suspicions about the ChangeDetector transformer were right. I deleted that part and actually I rebuilt the whole flow trying to get the results I expected and knew were right for the current data. So I cannot check anything related to it.

What I can tell you is that the IDs were the same fields in both and the same version of the transformer. 

I’ll try to reproduce the problem later today if I have the time and send the workspace to you.


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