Dealing with incompatible presumptions of commit protocols in multidatabase systems
Yousef J. Al-Houmaily, Panos K. Chrysanthis · 1996
A multidatabase system (MDBS) is a software system that is built on top of multiple pre-existing and heterogeneous database systems to facilitate their interoperation. This paper discusses the issue of compatibility among atomic commit protocols (ACPs) in a MDBS environment. Specifically, it shows that supporting a visible prepare to commit state is not enough for a successful integration of ACPs in an operational fashion because the outcome of some transactions might have to be remembered forever. Therefore, we define an operational correctness criterion that allows terminated transactions to be forgotten and propose Presumed Any, a Two-Phase Commit protocol variant that successfully integrates Presumed Nothing, Presumed Abort and Presumed Commit in a MDBS. We also show how the behavior of a local database system that employs presumed abort can be made to look as if it employs presumed commit and vice versa, allowing the MDBS to dynamically adapt to the most appropriate two-phase co...