A relational query language interface to a hierarchical database management system

The authors present an efficient structured query language (SQL) interface to an IMS hierarchical database management system (DBMS). This interface is a part of DATAPLEX, a heterogeneous distributed database management system that will provide location-transparent access to diverse databases using SQL in the engineering and manufacturing environment. The initial target DBMSs to be interfaced are IMS, DB2, and INGRES. For IMS, the hardest to provide with an SQL interface, an SQL interface called SQL/IMS was developed. A method which translates IMS data definitions is developed. A procedure which decomposes an SQL query into a set of simple IMS-processable queries and recomposes partial results is derived. SQL/IMS was tested using a small test database and a large production database. The performance of SQL/IMS is compared with that of another system used to access IMS data