The case for independent updates

The authors present the case for allowing independent updates on replicated databases. In autonomous, heterogeneous, or large scale systems, using two-phase commit for updates may be infeasible. Instead, the authors propose that a site may perform updates independently. Sites that are available can receive these updates immediately. But sites that are unavailable, or otherwise do not participate in the update transaction receive these updates later through propagation, rather than preventing the execution of the update transaction until sufficient sites can participate. Two or more sites come to agreement using a reconciliation procedure that uses reception vectors to determine how much of the history log should be transferred from one site to another. They also consider what events can initiate a reconciliation procedure.<>