I'm actually working on a backup and restore procedure of my salesforce data, and my client wants the ability to restore their chatter feed also.
I saw in the documentation (https://developer.salesforce.com/docs/atlas.en-us.api.meta/api/sforce_api_objects_feeditem.htm) that the upsert() call is allowed on the feedItem object. But what has not been specified, are the fields that are used to determine the update or insert.
Has anyone been able to do and upsert on the feeditem object ? What are the fields on which the update is determined ?