© 1998 by British Computer Society
Handling of Mutual Conflicts in Distributed Databases using Timestamps
Centre for Advanced Information Systems, Division of Software System, School of Applied Sciences, Nanyang Technological University, Singapore Email: askumar{at}ntu.edu.sg
In distributed database systems, it is desirable to allow read and write accesses to occur independently on replicated copies of database files in case of network partitions to increase availability. However, the system should detect mutual conflicts among the copies of the database files when sites from different partitions merge to form one partition. We present a timestamp-based algorithm for the detection of both write–write and read–write conflicts for a single file in distributed databases when sites from different partitions merge. Our algorithm allows read and write operations to occur in different network partitions simultaneously. When the sites from two different partitions merge, the algorithm detects and resolves both read–write and write–write conflicts with the help of stored timestamps using some additional information. Once the conflicts have been detected, we propose some reconciliation steps for the resolution of conflicts to bring the file into some consistent state. Our algorithm does not take into account the semantics of the transactions while detecting and resolving conflicts. Our algorithm will be useful in real-time systems where timeliness of operations is more important than response time (delayed commit).
Received December 5, 1997. revised July 7, 1998.