Applying distributed application global states monitoring to speculative query processing in RDBMS

The paper is concerned with the methodology for speculative query execution support in distributed Relational Database Management Systems (RDBMS). The proposed approach is based on the analysis of the multigraph representations of the stream of input queries arriving to a RDBMS. As a result, the optimized set of speculative queries is found to support execution of current queries. The speculative query results are used to speed-up execution of the query input stream. The paper presents how the proposed speculative query execution approach can be implemented inside a novel distributed program design framework PEGASUS DA in which program execution decisions are taken based on the system-supported monitoring of the distributed application global states. The paper shows the architecture of the speculative support provided by such framework for the distributed RDBMS and the assumed speculation approach. The implementation issues of the multithreaded distributed support based on the RDBMS SQLite engines are discussed. Distributed data synchronization and speculative query execution strategy as well as speculation results distribution are discussed. The proposed approach to distributed implementation of the speculative support to RDBMSs using the PEGASUS DA framework is illustrated on the example of the modifying query handling in a RDBMS facing the presented speculative query support for query execution.