A paper item under the [directory: distributed transactions](/nodes/377)

Two properties help with //scalability// of a transactional system: genuine partial replication (GPR), which leverages the intrinsic parallelism of a workload, and snapshot isolation (SI), which decreases the need for synchronization. However, it is ''impossible'' to have both SI and GPR.

SI is decomposed into four properties: 
- every transaction sees a committed state (ACA),
- every transaction observes a strictly consistent snapshot (SCONS),
- snapshots are monotonic (MON),
- write-conflict free (WCF)

> $SI = ACA \cap SCONS \cap MON \cap WCF$