Using PVM to Implement a Parallel Database System1)

MIDAS (MunIch Parallel DAtabase System) is a parallel relational database system. It is well suited to serve as a platform for the exploration of various strategies in order to parallelize a rela- tional database system. This short paper depicts how the abstract architecture of MIDAS looks like. A detailed description shows the implementation of a MIDAS prototype on a network of UNIX workstations. The core of the MIDAS protoype is implemented using PVM. But pure PVM does not fulfil all demands in order to implement a parallel database system. We demon- strate how our implementation combines the PVM programming model with standard UNIX mechanisms. We use UNIX shared memory to enhance the efficiency of our implementation and we use access privileges to UNIX files to secure the database against unauthorized access.