ADAPTABLE QUERY OPTIMIZATION AND EVALUATION IN TEMPORAL MIDDLEWARE

摘要

Time-referenced data are pervasive in most real-world databases. Recent advances in temporal query languages show that such database applications may benefit substantially from built- temporal support in the DBMS. To achieve this, temporal query optimization and evaluation mechanisms must be provided, either within the DBMS. This component accepts temporal SQL statements and produces a corresponding query plan consisting of algebraic as well as regular SQL parts. The algebraic parts are processed bz the middleware, while the SQL parts are processed by the DBMS. The middle ware uses performance feedback form the DBMS to adapt its partitioning of subsequent queries into middlwear and DBMS parts. The invention comprises the architecture and implementation of the temporal middleware component, termed TANGO, which is based on the Volcano extensible query optimizer and the XXL query processing library. Experiments withthe system demonstrate the utility of the middleware's internal processing capability and its cost-based mechanism for apportioning the processing between the middleware and the underlying DBMS.