
Distributed Database Systems
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sent, the time for completion of the commit processing, the level of parallelism permitted during
the commit processing, the number of state transitions that the protocols go through, the time
required for recovery once a site becomes operational after a failure, the number of log records
written, and the number of those log records that are force-written to stable storage. The conventional
two-phase commit protocol is extended for transaction commitment in R* system, which supports
a tree of processes. The presumed abort (PA) and the presumed commit (PC) protocols are defi ned
to improve the performance of ...