Implementation of queries based on relational algebra in a database management system



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To improve the efficiency of query implementation, the DBMS uses query-rephrasing mechanisms in the language processors and path selection algorithms in its access method to optimize the query before it is executed. With these system mechanisms which are transparent to the end-user, the execution time can be greatly reduced. The implementation part of the thesis concentrates on the physical file access method for the DBMS REQUEST. A File System using indexed sequential files with secondary indexing and several Relational Algebra Operations for the DBMS based on the Relational Model have been designed and implemented. Path selection strategies used to optimize the implementation of Selections and Joins allowed to achieve a significant improvement in the performance of the system.



Database management