I'm calling https://developers.arcgis.com/rest/services-reference/online/add-to-definition-feature-service-.htm
to add fields to a layer. Is there any documentation for what esriFieldTypeGlobalID and esriFieldTypeGUID are used for? I'd like to use one for the UUID that we use as a unique identifier but am unsure which to choose.
Also, are fields like: actualType, sqlType required?
I did a google search but can't seem to find any explanation.
Global IDs and GUIDs have a few differences. ArcGIS actively maintains Global ID fields (that is, when a new feature is created, a GUID value is assigned), whereas, GUID fields are left blank. ArcGIS will add a GlobalID field to a layer. You cannot edit the field, so if you need to edit the value, use a GUID type field. If you want ArcGIS to automatically enter the value, use the GlobalID field. Hope this answers your question.
Thanks so much! That's perfect. Any idea about actualType and sqlType?
I don't use either actualType or sqlType. I've had failures when I tried to set the sqlType. I'm not 100% sure, but I think the sqlType is set based on the backend (Enterprise systems might have different backend database systems).