Access to indexed hierarchical databases using a relational query language

摘要

An efficient means of accessing indexed hierarchical databases using a relational query language is presented. The purpose is to achieve an effective sharing of heterogeneous distributed databases. Translation of hierarchical data to an equivalent relational data definition, translation of a relational query language statement to an equivalent program that can be processed by a hierarchical database management system, and automatic selection of secondary indexes of hierarchical databases are investigated. A major portion of the result has been implemented, and the performance of the implemented system is analyzed. The performance of the system is satisfactory for a wide range of test data and test queries. It is shown that the utilization of the secondary index significantly enhances the efficiency in accessing hierarchical databases.