The eventId is the globally unique identifier carried by an inbound event, and it serves as the primary key of its EventInbox row. This is the linchpin of idempotent processing: if the same event is delivered twice, the second attempt to insert it under the same eventId collides with the existing row, so Relic never runs the same handler twice for one event. In effect, the eventId is what turns "at least once" delivery from another product into "exactly once" handling on Relic's side.
Technical section
Data model, API, and internals — visible to developers.