AFAIK, it is because UPSERT are only a subpart of MERGE. The devs plan to add real MERGE in a later release (9.5 or 9.6, I don't remember). Someone more knowled

AFAIK, it is because UPSERT are only a subpart of MERGE. The devs plan to add real MERGE in a later release (9.5 or 9.6, I don't remember). Someone more knowledgeable should shim in for the details.