A hierarchical controller for concurrent accessing of distributed databases

摘要

An access controller for a distributed database is a (central or distributed) structure which routes access requests to the different components of the database. Such a controller is also supposed to resolve the conflicts between concurrent requests, if any, such that deadlock situations never arise.

In this paper, some architectures for distributed access controllers of distributed databases are investigated. In particular, three controllers with hierarchical architectures are considered. The controllers are evaluated based on three criteria: (i) freedom of deadlocks, (ii) robustness, and (iii) parallelism. The third criterion implies that the added redundancy to increase the controller robustness against failure conditions should also contribute to the amount of achieved parallelism during the no-failure periods. We then define a controller architecture which satisfies all the three criteria.