RIA: Efficient Processing of Queries in Heterogeneous Database Systems Users not familiar with different types of database systems (including textual database systems) often have difficulty retrieving data stored in these databases. One popular method is to create a global schema from the schemas of existing databases and to allow the global schema to be queried. Each query against the global schema needs to be decomposed into subqueries which are then translated to queries acceptable by the corresponding underlying database systems for data retrieval. The objective of this project is to improve the processing speed of the global queries when using an object-oriented global schema. The speedup is achieved by two types of optimization mechanisms. One is built into the process of query decomposition and the other into query translation. The optimization in query decomposition evaluates different decomposition strategies and chooses the best strategy. The optimization in query translation similarly evaluates different translation plans. The existence of different types of databases requires that several translators be developed. Relational, object-oriented and textual database systems are used as the underlying database systems in the project. The proposed optimizations of queries against the global schema are expected to significantly improve the overall performance of heterogeneous database systems.
