A relational database machine Delta [2] has been developed at the Institute for New Generation Computer Technology (IOOT).The main component of Delta is an RDBE (relational database engine)[3] which performs relational database operations, such as projection and join.The RDBE consists of a sorting process hardware module called the sorter, a merging process hardware module called the merger, other special hardware modules called the IN module, a data input adapter, a data output adapter, and a CPU controlling these hardware modules.A special sorting cell was developed and implemented on LSI.The sorting process is based on a two-way merge-sort algorithm [l].~ne merging process is based on a hardware pipeline algorithm.In this paper, we describe the design considerations of the RDBE and these algorithms.Then, we describe the detailed design, implementation, and a performance evaluation of the RDBE.

A system for interfacing Prolog programs with relational algebra is presented. The system produces relational algebra queries using a deferred evaluation approach. Least fixed point (LFP) queries are automatically managed. An optimization method for removing redundant relations is also presented.

The Japan's Fifth Generation Computer System project is divided into three stages. In the first three-year stage, a working relational data base machine is developed for a software development support system to be used in the second stage and also for an experimental system which provides a research tool for the knowledge base machine.