Managing persistent objects in a multi-level store

This paper presents an architecture for a persistent object store in which multi-level storage is explicitly included. Traditionally, DBMSs have assumed that all accessible data resides on magnetic disk, and recently several researchers have begun to consider the possibility that significant amounts of data will occupy space in a main memory cache. We feel that future object managers will be called on to manage very large object bases in which time critical objects reside in main memory, other objects are disk resident, and the remainder occupy tertiary memory. Moreover, it is possible that more than three levels will be present, and that some of these levels will be on remote hardware. This paper contains an architectural proposal addressing these needs along with a sketch of the required query optimizer. 1