Final answer:
Serializability based on view equivalence is a database concept where two transaction schedules are considered equivalent if they result in the same final state and each transaction reads the same initial values as it would in the other schedule, following three main conditions involving read and write operations.
Step-by-step explanation:
Definition of Serializability Based on View Equivalence
Serializability based on view equivalence is a concept mainly used in the context of database systems to ensure that concurrent transactions yield results that are consistent with some order of serial execution. In essence, two schedules (or histories) of transactions are said to be view equivalent if they are able to produce the same final state and each transaction reads the same initial values as it would in the other schedule. The important conditions for this sort of equivalence include three main cases: (1) If a transaction T1 reads the initial value of a data item in one schedule, it must also read the initial value of that data item in the other schedule, (2) If T2 reads the value of a data item written by T1 in one schedule, T2 must also read the value written by T1 in the other schedule, and (3) If T1 is the last transaction to write to a data item in one schedule, it must also be the last to write to it in the other schedule.
View serializability is a form of serializability, and it is less stringent than conflict serializability, which requires that the order of conflicting operations is preserved. However, as long as the final outcome and read operations match, view serializability ensures that non-conflicting operations can be re-ordered, providing more flexibility in scheduling transactions while still maintaining database consistency.