This volume contains the papers presented at the Fourth International Workshop on Database Machines. The papers cover a wide spectrum of topics including descrip tions of database machine implementations. analysis of algorithms and database machine components. architectures for knowledge management. recovery and con currency control issues. and solutions to the 110 bottleneck problem. As at the pre vious workshops in Florence. San Diego. and Munich. a diverse collection of coun tries. universities. research labs. and database machine vendors were represented by the authors and conference attendees. Our thanks go to the authors for writing excellent papers and for their efforts in meeting deadlines. to the VLDB Endow ment for its cooperation. and to MCC for all its support. Finally. as usual. it is our secretaries that really deserve the credit for making the workshop a success. We wish to thank Cerise Blair of MCC for taking care of all the arrangements for the workshop and Sheryl Pomraning of the University of Wisconsin for her help in preparing this proceedings. Haran Boral March 1985 David J. DeWitt Table of Contents Architectures for Knowledge Processing "Associative Processing in Standard and Deductive Databases" K. Hahne, P. Pilgram, D. Schuett, H. Schweppe, G. Wolf . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "The Design and Implementation of Relational Database Machine Delta" T. Kakuta, N. Miyazaki, S. Shibayama, H. Yokota, K. Murakami . . . . . . . . . . . . . . . . . . . 13 Performance Evaluation I "The Equi-Join Operation on a Multiprocessor Database Machine: Algorithms and the Evaluation of their Performance" G. Z. Qadah . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ."