This paper discusses modifications to a database indexed storage that are specific to systems that wish to maintain all previous verions of data as well as to have access to the current data. Many such systems exist, including financial systems, transcript archives, and legal and medical records. These systems have the disadvantage that their storage requirements are always increasing, and in the past they have tended to be expensive compared to the value of the online storage. The advent of write once, read many (WORM) disk drives has reduced the cost of these systems. The problem is that these drives are literally write once. Thus the DBMS must plan carefully to write the index wanted correctly the first time.

In this paper, the authors describe a situation where current data is always stored on erasable random access devices, and the DBMS decides when to migrate data to the archive, which may be a WORM device. By keeping some of the archive on reusable media, the movement to archive can be done in a fashion that uses a larger portion of the WORM sector. The authors admit that this design is only research at present, but they are in the process of implementing a production system. That movement to production should either prove the potential of this algorithm or suggest possible improvements.