A model for adaptable systems for transaction processing

A model is presented for an adaptable system that allows online switching of classes of algorithms for database transaction processing. The basic idea is to identify conditions on the state of processing that will maintain consistency during the switch from one class to another. The classes of concurrency control algorithms and the formalism of history for transaction processing and serializability have been used to develop this research. In addition to the formalism, the precise conditions for switching digraph-serializable (DSR) algorithms have been given. This research is being applied to switching network partition protocols (conservative to optimistic), commit protocols, recovery block software, and has led towards the design of an adaptable and reconfigurable distributed database system. An experimental system called RAID has been implemented to test these ideas; it has been noted that adaptability provides for varying performance requirements and deals with failures of sites, transactions, and other components of the system