Isolation is one of the ACID properties of database transaction processing. Ideally, “concurrent” transactions are serializable, each occurring in isolation from the others, the results of each being independent of any changes resulting from the others. Normally, Teradata Database guarantees serializable transactions when the transaction isolation level is set to SERIALIZABLE for the transaction or for the session.
However, under some circumstances, CURRENT VALIDTIME selections from temporal tables can violate serializability in temporal transactions, even when the transaction isolation level is set to SERIALIZABLE. This can happen because of the interaction of two characteristics of temporal transactions:
This section illustrates the issues, and describes techniques that can be used to ensure serializable temporal transactions.