Overview of PIOS: a Physically Independent Object Server

PIOS (Physically Independent Object Server) is a prototype implementation of an object store intended to test some new ideas and techniques in the framework of the FIDE2 project. The main idea in PIOS is the support of physical objects' independence in an object store. Physical Independence allows the change of strategies in storing physical objects in the database without affecting the applications since they always see the same logical database schema. Physical Independence opens up opportunities to enhance performance in areas such query optimisation and high performance concurrency control. In this paper, an overview of the PIOS architecture is presented, stressing the new techniques implemented in the system to exploit physical independence in improving system performance.