Load * from a REST Connection creates __extra field

[kdaniels-obrien]

Hi,

I have a load script that requests data from a web service using a REST connection. Below is a small sample of my script.. 

TableName:
Load
*;
Sql Select
Col1,

Col2

From
JSON (wrap on) "root"
With connection (
URL "my/URL/here"
);

When I use the Load *, I get this field named __extra in my data model. If I specify the column names instead of a Load *, I do not get this __extra field.  For my use case and logic, I must be able to use a Load *. Right now my work around is to just drop that field but I really would like to understand:

1. Why  this field, __extra, is coming into my data model?

2.  What is this field? (It seems to always be null) 

3. Is there a way to use a load * without getting this __extra field? (with out a drop field) 

Thank you!! 

[Ken_T]

I am looking for the same answer to this same question - If I find it, I will update here

[marcus_sommer]

Maybe this field really exists or it's optional in regard to the rest-connection ...

- Marcus

[Ken_T]

I am not 100% sure - but based on my limited testing so far, 
if there is some process updating the data in where ever the REST connection is getting data from -

then this error can occur, and this mystery column will show in the error logs.

if it was a qmc-based reload task where it failed, the qmc task cannot be retriggered without the same error happening. (a cache issue maybe). even after the data in the REST connection source is stable (no other process adding new records/updating records) - the qmc task will fail if restarted.

however if the app is duplicated and reload is done in the HUB the error is gone. 
no changes to the app load script or data connection needed.
then the qmc-based reload will work again.

this is my current theory