Estimating temporary file sizes for query graphs in distributed relational database systems

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Virginia Polytechnic Institute and State University


This thesis implements a part of the front-end software, the Optimizer, of the distributed database system being developed at Virginia Tech. The Optimizer generates a strategy for optimal query processing, and it presents and analyzes a given query by means of query trees and query graphs. This thesis develops PASCAL procedures that implement quantitative and qualitative rules to select query graphs requiring minimum communication costs. To develop the rules, the size of the temporary files generated after performing each required operation is estimated. The focus of this work is on the implementation of a new technique for estimating the temporary file sizes. Detailed discussion of this implementation is presented and illustrated with a complete example, followed by a comparison with one of the existing methods proposed by Dwyer.