Optimization of Extended Relational Database Systems

摘要

Current relational Database Management Systems must be extended to function well in Engineering and Artificial Intelligence applications. Various additional functionalities have been proposed and in this thesis we study the optimization of one extended environment. Specifically, we consider the optimization of a version of the QUEL query language extended with two new features: the repetitive execution of commands; and the execution of relation fields in which collections of QUEL commands are stored. An extended query processing algorithm based on the original INGRES decomposition algorithm is first presented and then various modifications aiming to improve its performance are suggested. Caching of query results is also considered as another means to improve the performance of the processing engine. We analyze and suggest solutions to the various problems related to the design of a query result cache (replacement policies, invalidation techniques, etc). Based on the above extensions, a relation field may contain more than one QUEL commands. Accessing such a field triggers the execution of all these commands. We present a set of tactics that can be to reduce the cost of processing multiple commands using some interquery analysis. Special cases amenable to different kind of processing are also identified and studied.