The very first transaction is automatically created upon graph instantiation and is rooted to the BT.ROOT_NODE of the graph.
The zefDB user who instantiated the graph can be inferred from the very first transaction.
Any time a zefDB graph is loaded as primary instance in a process, this is considered the start of a primary session. This this is marked by a
BT.PRIMARY_SESSION_STARTING_EDGE going from the
BT.TX_EVENT_NODE node to the