PIPELINING MECHANISM TO MINIMIZE THE LATENCY TIME IN HIERARCHICAL MULTIMEDIA STORAGE MANAGERS

An emerging area of database system research is to provide support for continuous media data types (digital audio and video). These data typ es are expected to play a major role in applications such as library i nformation systems, scientific databases, entertainment technology, et c. They require both a high volume of storage and a high bandwidth req uirement for their continuous display. The storage organization of sys tems that support these data types is expected to be hierarchical, con sisting of one or more tertiary storage devices, several disk drives, and some memory. The database resides permanently on the tertiary stor age device. The disk drives store a number of frequently accessed obje cts, while the memory is used to stage a small fraction of a reference d object for immediate display. When a user references an object that is tertiary resident, if the system elects to materialize the object o n the disk drives in its entirety before initiating its display then t he user would observe a high latency time. This paper describes a gene ral purpose pipelining mechanism that overlaps the display of an objec t with its materialization on the disk drives in order to minimize the latency time of the system. The pipelining mechanism is novel because it ensures a continuous retrieval of an object to a display station ( in order to support its continuous display).