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Implementing Dynamic Code Assembly for Client-Based Query Processing

Joachim Thomas, Timo Gerbes, Theo Härder, Bernhard Mitschang

University of Kaiserslautern
P.O. Box 3049, 67653 Kaiserslautern, Germany
e-mail: haerder@informatik.uni-kl.de

Full paper (postscript version compressed by gzip)

Abstract:

Advanced database management systems (DBMS) are faced with increasingly complex query-processing tasks due to more powerful data models and query languages. These systems are usually conceived for client/server environments, with most application-oriented processing being done in the main-memory buffer at the client side. For performance reasons, it is indispensable to exploit the buffer contents when optimizing queries. As the buffer contents is only known at run time, advanced DBMS should support run-time optimization and offer concepts guaranteeing flexibility and efficiency of the subsequent phase of code generation. This paper addresses these issues. Our approach, dynamic code assembly, is based on a strictly orthogonal specification and implementation of the concepts involved in code generation, allowing to dynamically assemble executables from precompiled pieces of code, thus reducing explicit code generation to a minimum. We discuss our considerations and implementation referring to the KBMS KRISYS, although our ideas are generally applicable to advanced DBMS requiring run-time optimization and consequently flexible and efficient generation of executable code at run time.

Published in Proc. DASFAA`95, Singapore, April 1995, pp. 264-272.