Efficiency in databases is a major requirement. This paper presents some solutions to cope with this problem. One solution is to execute operations in parallel: this is done in the "Delta Driven Computer" DDC, which is a multiprocessor machine with distributed memory dedicated to relational and deductive databases. In DDC, relations are distributed among the nodes of the machine, and the data are processed asynchronously in each node. To do that in an efficient way, a coprocessor, specialized

more »

... r relational operations, is also proposed. It is called pSyC, for "microprogrammable Symbolic Coprocessor". This paper is divided into two parts. The first part describes DDC, presenting the architecture, the languages, and an original computational model. The second part describes @yC, its architecture, instruction set and the data structures used at the @yC level.