viewserializable

View serializable is a database correctness criterion for the interleaved execution of multiple transactions. A schedule of reads and writes is view-serializable if there exists a serial (non-concurrent) schedule of the same transactions that yields identical read results and the same final writes for every data item.

Intuitively, view serializability depends on the read-from relations rather than the exact order of operations. A schedule is view-serializable if, for each data item, every read in the schedule reads the value produced by some write in the serial schedule (or the initial value if no prior write exists), and the final writer of each data item in the schedule is the same as in the serial schedule. This focuses on the values observed by reads and the final state, rather than the precise sequencing of operations.

Relation to other notions: Every conflict-serializable schedule is view-serializable, but the converse is not guaranteed. View serializability is therefore a weaker criterion than conflict serializability, allowing more interleavings while still aiming for a serial-equivalent outcome with respect to reads and final writes.

Practical aspects: Determining view serializability for an arbitrary schedule is computationally harder than testing conflict serializability. As a result, most database management systems target conflict-serializability through concurrency control methods such as two-phase locking or timestamp ordering. View serializability remains an important theoretical concept for understanding the limits of concurrent execution and for proving correctness of certain algorithms and workloads.