On the equivalence of distributed systems with queries and communication

Distributed data management systems consist of peers that store, exchange and process data in order to collaboratively achieve a common goal, such as evaluate some query. We study the equivalence of such systems. We model a distributed system by a collection of Active XML documents, i.e., trees augmented with function calls for performing tasks such as sending, receiving and querying data. As our model is quite general, the equivalence problem turns out to be undecidable. However, we exhibit several restrictions of the model, for which equivalence can be effectively decided. We also study the computational complexity of the equivalence problem, and present an axiomatization of equivalence, in the form of a set of equivalence-preserving rewrite rules allowing us to optimize a system by rewriting it into an equivalent, but possibly more efficient system. Categories and Subject Descriptors C.2.4 [Distributed Systems]: Distributed databases General Terms Algorithms, Languages, Theory Key...

• Type: Journal
• Year: 2011
• Where: ICDT
• Authors: Serge Abiteboul, Balder ten Cate, Yannis Katsis
• Keywords: Computational Complexity, Data Management Systems, Database, Equivalence Problem, ICDT 2011