Pessimistic protocols for quasi-partitioned distributed database systems

The authors propose two protocols for transaction processing in quasi-partitioned databases. The protocols are pessimistic in that they permit the execution of update transactions in exactly one partition. The first protocol is defined for a fully partition-replicated database in which every partition contains a copy of every data object. The second protocol is defined for a partially partition-replicated database in which some objects have no copies in some partitions. Both protocols improve their major performance measures linearly with the backup link speed but are not visibly affected by either duration of the partitioning or the database size. This is a desirable property, since the backup link speed is the only controllable parameter