Solution: Don't use ESRI_OID.
TLDR: Downloading CSV's fails on Open Data. Data is served from Map Services hosting Query Layers from non-sde databases.
I have tables in MSSQL databases that I would like to offer on our Open Data site. I have published map services with these tables added as Query Layers, connected as either NT user ArcGISSOC and a database account. The service publishes fine and I'm able to see rows in the Data and Table tabs of AGOL and Open Data Admin site. REST queries to these services returns data as expected. Unfortunately when attempting to download the data as a spreadsheet I receive a generic error '...Something went wrong with the server....'. Logs on the server give a string of errors: 'General geodatabase error occurred , Error performing query operation. Wait time of the request to the service ... has expired, Unable to process request, no instances for .... were available for 60 seconds.'
ArcGIS Server 10.3
SQL Server 2008 R2
I'd like to know if Open Data is configured to accept Map Services with Query Layers configured in this way. If this isn't accepted, I'd like to know if there is an alternative that does not involve uploading CSV's to AGOL.
Thanks for your help