id field in order to uniquely identify a document.
A unique string value is auto-generated by the system if id field is not provided in an upsert request.
If you want to overwrite the entire document, you can do so by providing the id field in the document.
AIMP currently does not support a partial update operation.
Upsert limits
When upserting larger amounts of data, it is recommended to use
bulk-upsert operation.