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Joins On Tapes : Project Report †

In this paper, we report the construction of a simulator that was designed to measure the performance of various, new join methods which operate on tertiary storage devices. The simulator supports multiple device types with arbitrary number of drives of each kind. Modules and functionality found in relational database systems, such as hash tables, relation catalogs, and multi-page, interleaved input/output requests, are available in the simulator. Also included in the design principles of the simulator is an iterator function scheme which closely resembles that found in the query plan execution engine of commercial relational database systems. The new join methods are believed to offer far better performance on tertiary storage devices than conventional join methods (e.g., Grace and Hybrid Hash Joins). Indeed, new join methods such as Nested Block Join for Tape seem promising compared to their disk-based counterparts. The design and initial results of this simulator should be interesting to implementors of tertiary storage database systems.